Weatherwood 


INDEX 


PAGE 

The Company — Its Responsibility 

Products 1 

The Company — Its Experience 1 

Responsibility 1 

Manufacturing Facilities 1 

Personnel and Service 1 

How Weatherwood Is Marketed 1 

The Weather \'anc Trade Mark 1 

(A) Weatherwood — Manufacturing Process 

(Al) General 1 

(A2) Ideal Insulating Structure 1 

(A3) Details of Process 2 

(B) Physical Characteristics 

(Bl) Low Thermal Conductivity 2 

(B2) Size (Area) 2 

(B3) Thickness 2 

(B4) Weight 2 

(B5) Resistance to Moisture 3 

(B6) Structural Strength 3 

(B7) Plaster Bond 3 

(B8) Fire Resistance 3 

(B9) Sterility 3 

(BIO) Durability 3 

(Bll) Uniformity 4 

(B12) Non-compressil)ility — Resilience 4 

(B13) Joints 4 

(B14) Appearance 4 

(B15) Installation 4 

(B16) Cost 4 

(C) USES 

General Adaptability of Weatherwood 4 

Illustration Details 5 

(D) Importance of Good Construction 

(Preliminary Specification Data) 

(Dl) Introduction 4 

(D2) Materials 6 

(D3) Construction 6 

(D4) Anchors 7 

(D5) Window and Door Frames 7 

Tables : 

Working Stresses, Wood Joists 6 

Maximum Spans for Ceiling and Attic Floor Joists 0 

Alaximum Spans for Floor Joists 7 

Cross Bridging for Floor and Ceiling Joists 7 

Recommended Construction Details 8 

(E) Effective Insulation Thickness and Location 

(El) Heat Flow 9 

(E2) Roofs 9 

(E3) Exterior Walls 9 

(E4) Weatherwood as Sheathing and Roof Board- 
ing 9 

(E5) Insulating the Interior 9 

(F) Weatherwood as Sheathing and Roof 
Boarding 

(Fl) Use 10 

(F2) Sizes 10 

(F3) Advantages 10 

(F4) Specifications 10 

(F5) Supplementary Provisions 10 

(G) Weatherwood Insulating Lath 

(Gl) Use 10 

(G2) Size 10 

(G3) Advantages 10, 11 

(G4) Specifications 11 

(05) Supplementary Provisions 11 


PAGE 

(H) Weatherwood as Interior Finish 

(HI) Introduction 12 

(H2) Use 12 

(H3) Sizes 12 

(H4) Advantages 12 

(H5) Specifications 12 

(H6) Supplementary Provisions — Finishing, etc. 12, 13 

(J) Weatherwood as Exterior Finish 

(Jl) Use 13 

(J2) Sizes 13 

(J3) Advantages 13 

(J4) Specifications 13 

(K) Weatherwood Used as Added Insulation 

(Kl) Use 13 

(K2) Sizes 13 

(K3) Advantages 13 

(K4) Specifications 13, 14 

(K5) Supplementary Provisions 14 

(L) Weatherwood Insulation Over Roof Decks 

(Ll) Use 14 

(L2) Size (Area of Units) 14 

(L3) Thickness and Weights 14 

(L4) Advantages 14, 15 

(L5) Application over Wood Decks — Specifications 15 
(L6) Application over Concrete or Tile Roof 

Decks — Specifications 15, 16 

(L7) Application over Steel Decks — Specifications. 16 
(L8) Application under Steel Decks 16 

(L9) Determination of Heat Resistance of Indus- 
trial Roofs 

(L9a) General 16 

(L91)) Factors Involved 10, 17 

(L9c) Mathematical Computation for Fuel Saving. 17 

(L9d) Radiation Requirements 17 

(L9e) Mathematical Computation for Radiation 

Savings 17 

(L9f) Graphic Solution of Fuel and Radiation 

Savings 17 

Tables and Charts: 

Coefficients of Transmission (U) 18 

Climatic Conditions (U. S. Weather Bureau) 19 

Inside Temperature Usually Specified 19 

Chart for Graphic Solution of Fuel and Radiation 

Problems 20 

Relative Humidity 20 

(LIO) Prevention of Condensation 

(LlOa) General 21 

(LlOb) Factors Involved 21, 22 

(LlOc) Mathematical Computation of Condensation 

Conditions 22 

(LlOd) Graphic Solution of Condensation Prob- 
lems 22 

Charts: 

Charts for Graphic Solution of Condensation Prob- 
lems 23 

(M) Weatherwood Sound Deadening Construc- 
tion 

(Ml) The Need for Sound Deadening 24 

(M2) The Problem of Sound Deadening 24 

(M3) Sound Transmission 24, 25 

(AI4) Destruction of Sound Energy 25 

Sound Deadening Construction Details 25 


1 


B2581 


WEATHERWOOD: A STRUCTURAL INSULATING SOARD 


Manufactured by 

CHICAGO MILL AND LUMBER CORPORATION 

111 West Washington Street 
CHICAGO, ILL. 

Weatherwood 


INSULATES AGAIN S 


UNFRIENDLY WEATHER 


THE COMPANY 


ITS RESPONSIBILITY 


and 


Products 

(1) Weatherwood Insulating Board, i/^ in 
1 in. thick, 4 ft. wide by 8, 9, 10 and 12 ft. long. 

(2) Weatherwood Insulating Lath, Yo in. and 1 in. 
thick, 18x48-in. units with exclusive tongue and groove 
matched longitudinal edges. 

(3) Weatherwood Roof Deck Insulation, i/^ in. 
to 3 in. thick in multiples of i/^ in., 2 ft. wide by 5 ft. 
long. 

The Company — Its Experience 

Weatherwood is manufactured by the Chicago 
Mill and Lumber Corporation which has been con- 
tinuously in business since 1881 — a half century of suc- 
cessful accomplishment. The Corporation has long 
been a producer of lumber and wood products, and 
has acquired, together with its associated companies, 
a thorough knowledge of wood and fiber products. 
The research and engineering staff for many years 
has studied from every angle the production of mate- 
rials kindred to insulating board and the cumulative 
result of this experience is — Weatherwood. 

The Company enjoys an extremely satisfactory 
financial position, and with its associated companies 
represents a capital investment of approximately 
$62,000,000, with an annual business in excess of 
$30,000,000. 

The Chicago Mill and Lumber Corporation 
owns and operates extensive tracts of southern hard- 
wood in Louisiana, Arkansas, Mississippi and North 
Carolina and is in a position to produce a practically 
limitless and perpetual quantity of Weatherwood. 

Responsibility 

Our rating, the highest given in Bradstreet's and 
R. G. Dun's, is over $1,000,000— first grade of credit. 


Manufacturing Facilities 

Weatherwood is manufactured in a specially con- 
structed plant with the most modern equipment for the 
constant control of uniformity in process and product. 
Expanding production has been provided for in the con- 
struction of the plant, assuring an output equal to all 
demands. The plant is centrally located at Greenville, 
Miss., in the heart of the Company's southern hardwood 
tracts, with unexcelled shipping facilities. 

Personnel and Service 

The Insulation Division of the Chicago Mill and 
Lumber Corporation is under the management of some 
of the most capable and best known men in the insulat- 
ing material industry. Its Research Department is en- 
gaged in constant study and experiment to promote 
insulation improvements. 

To its Technical Department may be submitted all 
problems of application and decoration for insulation, 
structural, sound deadening or acoustical uses. 

How Weatherwood Is Marketed 

Weatherwood is marketed nationally, through the 
better Retail Lumber Dealers who maintain local stocks 
of all types of Weatherwood. 

The Weather Vane Trade Mark 

The Weathercock weather vane is the trade-mark 
of Weatherwood and "the symbol of insulation effi- 
ciency." Through our dealers,, we will furnish an 
attractive, practical weather vane in the shape of our 
Weathercock trade-mark to install on the roof of each 
building in which Weatherwood has been used in a 
proper and representative way. This unusually attrac- 
tive weather vane carries no advertisement. 


(A) WEATHERWOOD— MANUFACTURING PROCESS 


(Al) General 

Weatherwood is an insulating board designed and 
manufactured for use in all types of structures as an 
insulation against heat loss and sound transmission. 

(A2) Ideal Insulating Structure 

Weatherwood is the only insulating board fabri- 
cated from hardwood. 

The insulating efficiency of any material is largely 
dependent on the number and size of its confined struc- 


tural air cells — the greater the number and the smaller 
the size of the individual cells the greater the efficiency. 
It is a well-known fact that hardwood fibers are 
tiny, closed-end cells. Hardwood fibers are not sap 
ducts, but are clustered around the duct areas. Soft- 
wood fibers, on the other hand, are mostly continu- 
ous tubes or ducts through which the tree elevates its 
sap. 

The microscopic, confined air cells of the individual 
hardwood fibers, combined with the multitude of small 


Sweet's 


PAGE 1 


Continued on next page 


B2582 


Chicago Mill and Lumber Corporation 


air cells created between the fibers when these are felted 
or fabricated in Weatherwood, results in an ideal insu- 
lating structure of great efficiency. 

(A3) Details of Process 

(A3a) Raw Stock — Weatherwood is made largely 
from the waste from certain species of Southern hard- 
woods. This includes miscellaneous trimmings from 
sawmills, as well as trimmings and cuttings in the 
logging operations which are too small for lumber 
utilization. This material represents the strongest, 
toughest part of the trees so far as the fiber is con- 
cerned. 


(A3b) Fiber Reduction 

trimmings and logwood ar- 
riving at the insulation mill 
are first passed through 
barkers which completely 
remove the unsuitable bark. 
The remaining clean wood 
is then delivered to the fiber- 
reducing equipment which 
grinds it into the various 
types of fiber constituting 
the finished board. It is the 
particular mixture of fibers, 
individually and in bundles, 
that makes possible the felt- 
ing of the entire mass into 
a strong, homogeneous 
board. 

(A3c) Weatherproof- 
ing and Preservative 
Treatment — Prior to the 
felting of the fiber into the 
sheets of Weatherwood, the 
*'stock" is treated with a 
waterproofing solution, 
which is uniformly precipi- 
tated on each individual fiber 
of the entire mass. The 
weatherproofing of a board 
of this character is accom- 
plished by the formation of 


Process — All of the 


of 


Section of Hardwood 

This section is enlarged approximately 9% times showing 
the closed-end fiber. "AR ' is the annular ring made uo 
'S" spring wood and **SW" summer wood. "MR 


transverse medullary ray. "P" is a sap duct formed by the 
clustered, surrounding fibers "F." 

This cut is shown through the courtesy of The Forest 
Products Laboratory 


a film coating over each fiber which seals the fiber and 
offers a high surface tension which further protects it 
from moisture. The waterproofing treatment is con- 
summated with the setting of the size in the drying 
process (see (A3e)). 

The weatherproofing agent also acts as a steriliz- 
ing and preservative treatment for the wood fibers. 

(A3d) Felting Process — After the various types 
of fiber have been prepared and the mass reduced to 
the proper consistency by the addition of clean water, 
the mixture or '*stock" passes on to an improved type 
of felting machine, where the fibers are felted into the 
finished boards, leaving the felting machine in a very 
wet condition. 

This process felts the 
board, full ^ in. thick, in 
one homogeneous mass in- 
stead of combining several 
layers; thus the board, free 
of lamination, is not prone 
to split and is extremely du- 
rable in handling and use. 

(A3e) Drying Process 

— The wet sheet of Weath- 
erwood, now fabricated, 
passes slowly through a dry 
kiln of the air circulation 
type. Here, the rapid circu- 
lation of dry, warm air re- 
moves the excess moisture 
from the board and at the 
same time so sets the weath- 
erproofing and preservative 
that moisture has very little, 
if any, effect on the finished 
product. 

(A3f) Cutting— As the 

board comes from the dry- 
er, it is cut to the size re- 
quirements of the various 
products and, passing along 
diverse lines, is assembled, 
finished and prepared for 
shipment. 


shows a 


(B) PHYSICAL CHARACTERISTICS 


(Bl) Low Thermal Conductivity 

The thermal conductivity of Weatherwood has been 
established by various nationally known testing labora- 
tories. The average conductivity established is .32 
B.t.u.^s per hour, per sq. ft., per degree F., per inch 
thickness. The following test conducted by G. F. Geb- 
hardt, (J. C. Peebles, Testing Engineer) at the Labora- 
tories of Armour Institute of Technology, is typical. 


HEAT CONDUCTIVITY OF WEATHERWOOD INSU- 
LATING BOARD— FLAT PLATE METHOD 


Thickness, 
in. 


Density, 
lbs. cu. ft. 


Heat conductivity, B.t.u.'s per hour 


1 in. thick 


0.502 in. thick 


0.502 


15.2 


0.32 


0.64 


(B2) Size (Area) 

The standard board is 4 ft. wide by 8, 9, 10 or 12 ft. 


long. Weatherwood Insulating Lath is 18 in. by 48 in. 
Weatherwood Roof Insulation is 2 ft. by 5 ft. 

(B3) Thickness 

The Weatherwood boards are fabricated full % in. 
thick. All of the various products are marketed in this 
thickness and in 1-in. thickness as well. 

The 1-in. thick Weatherwood is made up of two 
thicknesses of the i/^-in. stock, rigidly secured together 
by means of metal staples. This method combines the 
two i/^-in. thick boards permanently into a practical unit 
full 1 in. thick. 

See particularly (L3a) page 14 describing in detail 
the method of manufacturing Stapled Roof Deck Insu- 
lation units up to 3-in. thickness. 

(B4) Weight 

Weatherwood weighs 650 lb. per 1000 sq. ft. of 
half inch material; inch thickness weighs twice as 
much, etc. 


Sweet's 


PAGE 2 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2585 


(B5) Resistance to Moisture 

In the process of manufacture, the complete fiber 
content is treated to resist absorption of moisture (see 
(A3c) page 2). Laboratory tests show that the board 
has an extremely low absorption factor and practically 
no capillarity. 

The insulating efficiency of any material is imme- 
diately reduced if it absorbs and holds moisture, due to 
the fact that water is an excellent heat conductor. 
Weatherwood under normal building installations may 
be considered practically moistureproof. 

The following tests conducted by G. F. Gebhardt, 
(J. C Peebles, Testing Engineer) at the Laboratories 
of Armour Institute of Technology, are typical. 

Water Absorption Test 

In making this test two samples of the board meas- 
uring 12x12 in. by approximately i/^ in. in thickness 
were used. These samples were placed in a horizontal 
position in a large vessel containing water, so that the 
upper surface of the boards was exactly 1 in. below the 
surface of the water. Each sample was supported on 
two y2-in. brass rods and held down with sufficient 
weight to keep the sample submerged. Two brass rods 
were also placed on the upper surface of each test sam- 
ple to support the above mentioned weight. In this 
way, practically the entire surface of the test sample 
was in contact with the water. 

In order that the water might be maintained sub- 
stantially pure during the test fresh water was supplied 
at one side of the tank and allowed to flow over a weir 
at the other side. This water was maintained through- 
out the test at a constant temperature of 62° F. At the 
expiration of two hours the samples were removed from 
the water and the surface moisture removed with blot- 
ting paper. They were then weighed and the increase 
in weight expressed as a percentage of the original dry 
weight. The results are as follows: 


WATER ABSORPTION TEST 
WEATHERWOOD INSULATING BOARD 


Sample 


Size, in. 


Weight in grams 


Increase in weight 


Before 


After 


Grams 


Per cent 


No. 1 
No. 2 


12x12x0.54 
12x12x0.54 


332.2 
333.6 


373.0 
375.0 


40.8 
41.4 


12.3 
12.4 


Capillarity Test 

In conducting this test two samples of the board 
measuring 4x4 in. by approximately i/^ in. thick were 
used. These samples were placed in a desiccator over 
sulphuric acid for a period of 24 hours. They were 
then carefully weighed and placed in a closed vessel 
containing water. Each sample was placed on edge in 
such a position that it dipped into the water exactly 
y2 in. The vessel was then sealed airtight and main- 
tained for 24 hours at a temperature of 70° F. The 
samples were then removed and weighed and the in- 
crease in weight converted to volume of water absorbed, 
expressed in cubic inches. 


CAPILLARITY TEST 
WEATHERWOOD INSULATING BOARD 


Sample 


Size, in. 


Water absorbed, 
cu. in. 


No. 1 

No. 2 


4x4x0.54 
4x4x0.54 


0.445 
0.438 


(B6) Structural Strength 

The hardwood fibers of which Weatherwood is 
composed are tough and resilient. Tests on Weather- 
wood used as sheathing prove that when properly 
applied, the %-in. thick board is over twice as strong 
(so far as bracing against distortion) as standard if -in. 
thick matched lumber sheathing applied horizontally in 
the customary manner. Weatherwood also possesses 
distinct advantages over diagonal sheathing, in that it 
is not prone to shrinkage or expansion after application, 
which tends to throw strains into the framework and is 
much more economical to apply. 

Weatherwood has a tensile strength of over 300 lb. 
per sq. in., and a modulus of rupture of over 400 lb. per 
sq. in., fiber stress, bending. 

(B7) Plaster Bond 

Authentic tests show that to rupture the bond be- 
tween gypsum plaster and Weatherwood Lath requires 
over 1350 lb. per sq. ft. Even then, the rupture occurs 
in the board itself and not at the bond surface. The 
strength of this plaster bond is more than twice that of 
wood lath and plaster, which experience has proven 
entirely adequate. 

The following test conducted by Robert W. Hunt 
Company, Engineers, Chicago, is typical: 

Three samples, approximately 6 in. square, were 
plastered with wood fiber plaster and after curing for 
seven days were secured by asphalt to wooden blocks on 
each side of the specimen. The wooden blocks were 
then secured in the testing machine and in attempting to 
pull them apart, tension was generated on the specimens 
tending to pull the plaster away from the insulating 
board, with the results below. 

Failure in each case was through the Weatherwood 
close to the asphalt by which it was secured to the 
wooden block. 


PLASTER BOND 
WEATHERWOOD INSULATING LATH 


Specimen No. 


1 


2 


3 


6.00x6.05 


5.98x5.95 


5.98x6.00 


Area, sq. ft 


.2521 


.2471 


.2492 


Maximum load, lb. 


345 


235 


310 


Maximum load, lb. 
per sq. ft 


1369 


951 


1255 


(B8) Fire Resistance 

Weatherwood is slow-burning. Due to the fact 
that there are no open joints to permit inflow of air, 
Weatherwood forms a barrier against fire travel. 


(B9) Sterility 

Made only of clean, sterilized hardwood fibers it is 
odorless under all conditions. Its weatherproofing 
chemical treatment during the manufacturing process 
(see (A3c) page 2), makes it distinctly distasteful to 
rodents and insects. 

(BIO) Durability 

The hardwood fibers, from which Weatherwood is 
fabricated, are the toughest and most resilient in the 
tree growth (see (A3a) page 2), in addition to which 
all the fibers are treated with a preservative (see (A3c) 
page 2). 


Sweet's 


PAGE 3 


Continued on next page 


B2584 


Chicago Mill and Lumber Corporation 


(Bll) Uniformity 

Adequate laboratory control and mill inspection 
assure absolute uniformity in density, structural strength 
and appearance. Handling facilities and packing 
methods eliminate damage under normal shipping con- 
ditions. 

( B 1 2 ) Non-compressibility — Resilience 

When laid over roof decks under standard roof- 
ing materials, it is sufficiently firm to prevent injuri- 
ous denting or cutting of the roofing under normal 
use. Weatherwood will not compress under furring 
strips. When compressed under heavy concentrated 
loads it resumes its original shape after the load is 
removed. 

(813) Joints 

Due to the size of the boards (4 ft. wide by 8, 9, 
10 and 12 ft. long) and the method of installation, the 
unbroken continuity, essential in the solution of insu- 


lation problems, is easily maintained. The exclusive 
Weatherwood Lath tongue and groove, long-side joint 
maintains similar continuity where these units (18x48 
in.) are used. 

(814) Appearance 

One surface is finished in a uniform semirough 
texture and the other in a smooth screen surface. The 
color is an attractive deep cream. 

(815) Installation 

The board is light in weight and in all of the various 
convenient sizes it is easy to handle and install at low 
labor costs. It is cut and nailed like lumber. 

(816) Cost 

Conservation of waste materials, quantity produc- 
tion and national distribution through established trade 
channels assure a reasonable cost absorbed in fuel sav- 
ings in from four to five heating seasons. 


(C) 

(Cl) General — Weatherwood, a structural insu- 
lating board made in two commercial thicknesses (full 
in. and full 1 in.), is designed, as set forth in 
(B) "Physical Characteristics," pages 2, 3 and 4 to ful- 
fill every building insulation need. 

The main purpose of all building insulation is to 
prevent heat loss through the exterior walls and roofs 
in cold weather and to exclude the heat from the sun's 
rays in warm weather — justified not only by the econ- 
omies of fuel conservation but as well by increased 
comfort reflected in beneficial effects on health. 

When properly installed, Weatherwood is an excel- 
lent insulation against sound transmission. 

Below are briefly outlined the various uses and 
applications of Weatherwood, each subsequently treated 
in detail. 

(C2) As Sheathing and Roof Boarding — Under 
wood siding, stucco, masonry veneer, shingles or slate, 
etc. 

(C3) As Roof Insulation — Over wood, concrete, 
steel or tile roof decks to be covered with a roofing 
material. 

(C4) As Insulating Lath — To receive interior 
plaster. 

(C5) As Interior Finish (without Plaster) — 

Either in its natural finish or stained or painted. It is 


an excellent base for plastic paints and may be used as 
a base for wall paper. 

(C6) As Interior Lining for Sound Absorption 
— To provide proper acoustical conditions for halls, 
gymnasiums, churches, schools, etc. 

(C7) As Exterior Finish — Painted, it has many 
uses as an exterior exposed finish in the lighter, less 
permanent constructions where cost is a prime factor. 

(C8) As Added Insulation — Added to the usual 
constructions purely for its insulating value as follows : 

(a) Over exterior wood sheathing covered by addi- 
tional exterior finish. 

(b) Under or over wood roof sheathing covered 
with shingles or other roofing materials. 

(c) Over interior wood studs, joists or other 
framework with an additional plaster base furred out or 
placed immediately over it. 

(d) Between rough and finished floors. 

(e) Over wood, concrete, steel or tile roof decks to 
be covered with a roofing material. 

(C9) As Insulation for Masonry Walls — Applied 
over furring strips, as insulating lath, as interior finish 
or as insulation only. 

(ClO) As a Sound Deadener — In partitions and 
floor to prevent the transmission of sound from one 
room to those adjoining. 


(D) IMPORTANCE OF GOOD CONSTRUCTION 

Preliminary Specification Data 


( D 1 ) Introduction 

Weatherwood Structural Insulation requires no 
special construction features for successful application. 
Experience has shown, however, that so frequently are 
the basic principles of good construction violated, it 
is important to stress here the salient points; and 
particularly so, since the building construction is cus- 
tomarily provided for in other divisions of the speci- 
fication. 

We recommend that the details for good construc- 
tion as approved by the building code committee of the 
U. S. Department of Commerce and the National Lum- 
ber Manufacturers Association be adhered to. Good 
construction does not add appreciably to the cost. 

In no place in the building construction is faulty 
construction more apparent than in the resulting cracks 
in the interior plastering. That the lath and plaster is 


not always responsible for cracking of plastered sur- 
faces is indicated by the following quotation from the 
National Building Code Committee report. 

^'Following are some of the common causes which 
result in cracked plaster : 

(1) Inadequate or faulty footing under bearing 

posts. 

(2) Girders too small or too few bearing posts. 

(3) Joists of insufficient size. 

(4) Joists under partition not doubled. 

(5) Improper framing over wide openings. 

(6) Uneven settlement due to shrinkage of wood 

frame improperly designed. 

(7) Settlement of wall footing and foundation. 

(8) Separation of partitions from walls. 

(9) Failure to conform to good plastering stand- 

ards." 


Sweet's 


PAGE 4 


Continued on next page' 


Chicago Mill and Lumber Corporation 


B2585 


WEATHERWOOO 

— used as 
j-oof boarding 


Note --First floor construction, 
as shown, \s recommended for 
reducing furnace noises. 


WEATHER- 
WOOD 


GENERAL ADAPTABILITY OF WEATHERWOOD 


Sweet's 


PAGE 5 


Continued on next page 


B2586 


Chicago Mill and Lumber Corporation 


WORKING STRESSES— Joists, Planks, Beams and 
Stringers — Continuously Dry 
(Pounds per Square Inch) 
Recommended by Forest Products Laboratory, United States For- 
est Service, for Grades Complying with the Minimum Basic 
Structural Provisions of American Lumber Standards 


Species 


Cedar: 

Alaska 

Northern and 
southern white. 

Port Orford . . . 

Western red . . . 

Cypress: 

Southern 

Douglas fir: 

Coast type .... 

Rocky Moun- 
tain type 

Fir: 

Balsam 

Golden, noble, 
silver, white. . . 

Hemlock : 

Eastern 

West Coast 

Larch : 

Western 

Pine : 

California, Ida- 
ho and northern 
white, Pondosa, 
and sugar 

Norway 

Southern yellow 

Redwood 

Spruce: 

Engelmann .... 
Red, white, and 
Sitka 

Tamarack 


Maxi- 


American 


rLxtreme 


mum 


standard 


fiber in 


hori- 


grade 


bending 


zontal 


shear 


f Select 


1,100 


90 


1 Common 


880 


72 


Select 


750 


70 


ICommon 


600 


56 


Select 


1,100 


90 


ICommon 


880 


72 


Select 


900 


80 


\Common 


720 


64 


Select 


1,300 


100 


\ Common 


1,040 


80 


Dense select 


1 ,750 


105 


Select 


1.600 


90 


Dense common 


1,400 


103 


Common 


1,200 


72 


Select 


1,100 


85 


[Common 


880 


68 


Select 


900 


70 


[Common 


720 


56 


Select 


1,100 


70 


\Common 


880 


56 


Select 


1 100 


7n 
/ u 


(Common 


880 


56 


Select 


1,300 


75 


\ Common 


1,040 


60 


(Select 


1,200 


100 


1 Common 


960 


80 


Select 


900 


85 


[Common 


720 


68 


(Select 


1,100 


85 


^Common 


880 


68 


Dense select 


1,750 


128 


Dense common 


1,400 


103 


Common 


1,200 


88 


Select 


1,200 


70 


[Common 


960 


56 


Select 


750 


70 


Common 


600 


56 


Select 


1,100 


85 


Common 


880 


68 


Select 


1,200 


95 


( Common 


960 


76 


Com- 
pression 
perpen- 
dicular 
to grain 


250 

175 

250 

200 

350 

380 
345 
380 
325 
275 

150 

300 

300 
300 


Modulus 
of 

elasticity 


1,200.000 
800,000 
1,200.000 
1,000,000 
1 ,200,000 

.1,600.000 

1,200,000 
1,000.000 
1,100,000 

1,100,000 
1,400.000 


250 


1.000,000 


300 


1,200,000 


380 
380 
325 


) 1.600,000 

J 


250 


1,200,000 


175 


800,000 


250 


1.200.000 


300 


1,300.000 


(D2) Materials 

The species of framing material as well as the 
proper size should be carefully selected for its specific 
use. Only thoroughly seasoned lumber should be 
used. 

The warping, twisting, excessive shrinkage and de- 
flection of the framing members are responsible largely 
for cracks in stucco, masonry veneer and interior plas- 
ter whether the sheathing be wood or structural insula- 
tion such as Weatherwood, or whether the plaster base 
be wood, metal, gypsum or Weatherwood Insulating 
Lath. 

While Weatherwood Sheathing is extremely strong 
(see (B6) page 3), no form of sheathing will prevent 
distortion due to improperly selected, unseasoned fram- 
ing members. 

The tables on this and the following page are rec- 
ommended in the selection of framing materials. 

(D3) Construction 

There are three general types of wood frame con- 
struction in common use — namely, "balloon frame," 
"braced frame" and "Western frame." Lumber shrinks 
at right angles to the direction of the grain. Since the 
"balloon frame" construction eliminates to the greatest 
extent the element of lumber shrinkage it is particularly 
recommended. 

In all three types of framing the comer bracing is 
a most important feature which should never be omitted. 
Whether the sheathing be wood, applied horizontally or 
diagonally, or structural insulation board, such as 
Weatherwood (see (B6) page 3), the diagonal corner 
bracing is desirable. 

Always include the recommended fire and heat 
stops in "balloon" and "braced frame" constructions. 

To summarize the salient recommended construc- 
tion features we include the details shown on page 8. 


MAXIMUM SPANS FOR CEILING JOISTS AND ATTIC FLOOR JOISTS, Uniformly Loaded 


Nominal 

size of 
joists, in. 


Spacing 
of 

of joists, 
center to 
center, in. 


Maximum allowable lengths between supports (clear span) 


Limited by deflection of ^/m of the span 
Having determined by reference to the building code or the above table the allowable modulus of elasticity in pounds per square inch 
for the species of timber used, refer to the column below with the corresponding value to determine maximum safe span 


Ceiling joists 


Attic floor joists, livt load 20 lb. per sq. ft. 


£=1,000,000 


£ = 1.200.000 


£=1.400.000 


£ = 1,600.000 


£=1.000,000 


£ = 1,200,000 


£ = 1,400.000 


£ = 1,600.000 


2X 4 1 


12 
16 
24 


9' 4" 
8' 7" 
7' 1" 


10' 0" 
9' 2" 
8' 1" 


10' 6" 
9' 8" 
8' 6" 


11' 0" 
10' 0" 
8' 11" 


6' 6" 

5' 11" 

5' 3" 


7' 0" 
6' 3" 
5' 7" 


7' 4" 
6' 8" 
5' 10" 


7' 8" 
6' 11" 
6' 1" 


2X 6 1 


12 
16 
24 


14' r 

w y 

W 8" 


15' 5" 
14' 0" 
12' 5" 


15' 10" 
14' 8" 
13' 0" 


16' 7" 
15' 4" 
13' 8" 


10' 0" 
9' 1" 
8' 1" 


10' 9" 
9' 8" 
8' 7" 


11' 3" 
10' 2" 
9' 0" 


11' 0" 
10' 8" 
9' 7" 


2X 8 1 


12 

16 

24 


18' 6" 
17' 2" 
15' 4" 


19' 8" 
18' 3" 
16' 4" 


20' 0" 
19' 3" 
17' 2" 


21' 8" 
20' 2" 
18' 0" 


13' 4" 
12' 1" 
10' 9" 


14' 2" 
12' 10" 
11' 5" 


14' 11" 
13' 6" 
12' 0" 


15' 7" 
14' 2" 
12' 7" 


2X10 1 


12 
16 
24 


23' 0" 
21' 4" 
19' 3" 


24' 5" 
22' 9" 
20' 5" 


25' 8" 
24' 0" 
21' 6" 


26' 10" 
25' 0" 
22' 6" 


16' 9" 
15' 3" 
13' 7" 


17' 9" 
16' 2" 
14' 5" 


18' 9" 
17' 0" 
15' 2" 


19' 7" 
17' 9" 
15' 10" 


2X12 1 


12 
16 
24 


27' 2" 
25' 6" 
23' 0" 


28' 11" 
27' 0" 
24' 5" 


30' 0" 
28' 6" 
25' 9" 


29' 9" 
26' 10" 


20' 0" 
18' 4" 
16' 4" 


21' 4" 
19' 5" 
17' 4" 


22' 6" 
20' 6" 
18' 3" 


23' 6" 
21' 5" 
19' 1" 


Note: The lengths are based on: Maximum allowable deflection of 1/360 of span length. Modulus of elasticity as noted for E. 

Ceiling Joists Attic Floor Joists 

Dead load: Weight of joists plus plaster ceiling (10 lb. per sq. ft.) Dead load: Weight of joist. Weight of lath and plaster ceiling 
Live load: None. (10 lb. per sq. ft.). Single thickness of flooring (2.5 lb. per sq. ft.). 

Live load: 20 lb. per sq. ft. of floor area. 


Sweet's PAGE 6 

Continued on next page 


Chicago Mill and Lumber Corporation 


B2587 


(D4) Anchors 

Where Weatherwood is used as sheathing and roof 
boarding, exterior finish or interior finish (see section 
(C) "Uses" page 4), it is recommended that the 
framed superstructure be well anchored to the founda- 
tion. This is due to the fact that the Weatherwood, an 
extremely light material, is substituted for the heavier 
standard wood sheathing, exterior siding, etc., or lath 
and plaster and the anchors are desirable to compensate 
for the reduced weight. 

(D5) Window and Door Frames 

Weatherwood Sheathing and Weatherwood Insu- 
lating Lath do not require special window and door 
frames (see details on page 8). It is strongly recom- 
mended that in frame construction the window and door 
frames, whether of stock or special design, be provided 
with wide outside blind casings (often omitted) and 


inside ground casings. Authentic tests show that the 
air infiltration or leakage around windows where these 
members are omitted is equal to the air leakage through 
an unweatherstripped window. To prevent air leakage 
around wood frames in masonry openings, they should 
be thoroughly calked with oakum or similar material 
from the inside. 

In the average uninsulated dwelling the estimated 
heat loss through and about the exterior doors and win- 
dows is from 40 to 45 per cent — from 55 to 60 per cent 
is lost through walls and roofs. 

Worthwhile reduction of this heat loss at doors 
and windows may easily be accomplished by proper de- 
sign and construction, calking, weatherstrips and storm 
sash. 

Often much of the economy and comfort of well 
insulated walls is lost through poorly constructed, im- 
properly installed, air leaking windows and doors. 


MAXIMUM SPANS FOR FLOOR JOISTS, Uniformly Loaded 

(Live load 40 lb. per sq. ft. with plastered ceiling. Live load 50 lb. per sq. ft. with unplastered ceiling) 


Nominal 
size of 
joists, 
inches 


Spacing 

of 
joists 
center 

to 
center, 
inches 


Maximum allowable lengths between supports (clear span) 


Limited by deflection of i sfio of the span. 
Having determined by reference to the 
building code or the table on page 6 the 
allowable modulus of elasticity in pounds 
per square inch for the species of timber 
used, refer to the column below with the 
corresponding value to determine span 


Determined by bending 
Having determined by reference to the building code or the table on page 6 the allowable 
extreme fiber stress in bending in pounds per square inch for the species and grade of lumber 
used, refer to the column below with the corresponding value to determine maximum 

safe span 


LOGO, 000 


1 .200.000 


E = 
1,400.000 


E = 
L600.000 


/ = 
900 


/= 

1.000 


/ = 

1,100 


/ = 

1,200 


/ = 

1.300 


/ = 

1,400 


/ = 

1.500 


/ = 

1.600 


/ = 

1.700 


/ = 

1.800 


2X 6 1 


12 

16 

24 


8' 6" 
V 9" 
6' 10" 


9' 1" 
8' 3" 
7' 3" 


9' 6" 
8' 8" 
7' 7" 


10' 0" 
9' 1" 
8' 0" 


9' 6" 
8' 3" 
6' 9" 


10' 0" 
8' 8" 
7' 1" 


10' 5" 
9' 1" 
7' 6" 


10' 11" 
9' 6" 
7' 10" 


11' 4" 
9' 10" 
8' 1" 


11' 10" 
10' 3" 
8' 5" 


12' 2" 
10' 8" 
8' 9" 


12' 7" 
11' 0" 
9' 0" 


13' 0" 
11' 4" 
9' 3" 


13' 5" 
11' 7" 
9' 6" 


{ 

2X 8 1 


12 
16 
24 


ir 5" 

10' 5" 
9' 2" 


12' 0" 
11' 0" 
9' 8" 


12' 8" 
11' 7" 
10' 2" 


13' 3" 
12' 1" 
10' 8" 


12' 6" 
10' 11" 
8' 11" 


13' 2" 
11' 6" 
9' 5" 


13' 10" 
12' 0" 
9' 11" 


14' 5" 
12' 7" 
10' 4" 


15' 0" 
13' 1" 
10' 9" 


15' 7" 
13' 8" 
11' 2" 


16' 1" 
14' 1" 
11' 7" 


16' 8" 
14' 6" 
12' 0" 


17' 2" 
15' 0" 
12' 4" 


17' 8" 
15' 5" 
12' 8" 


2X10 


12 
16 
24 


14' V 
13' 1" 
11' 6" 


15' 2" 
13' 10" 
12' 2" 


16' 0" 
14' 7" 
12' 10" 


16' 8" 
15' 3" 
13' 5" 


15' 9" 
13' 9" 
11' 4" 


16' 7" 
14' 6" 
11' 11" 


17' 4" 
15' 2" 
12' 6" 


18' 2" 
15' 10" 
13' V 


18' 11" 
16' 6" 
13' 8" 


19' 7" 
17' 1" 
14' 1" 


20' 3" 
17' 9" 
14' 7" 


21' 0" 
18' 4" 
15' 1" 


21' 8" 
18' 10" 
15' 7" 


22' 3" 
19' 5" 
16' 0" 


2X12 


12 
16 
24 


17' 3" 
15' 9" 
13' 10" 


18' 3" 
16' 9" 
14' 9" 


19' 3" 
17' 7" 
15' 6" 


20' 1" 
18' 5" 
16' 2" 


18' 11" 
16' 6" 
13' 8" 


19' 11" 
17' 5" 
14' 4" 


20' 11" 
18' 3" 
15' 1" 


21' 11" 
19' 1" 
15' 9' 


22' 8" 
19' 11" 
16' 5" 


23' 6" 
20' 7" 
17' 0" 


24' 5" 
21' 4" 
17' 7" 


25' 2" 
22' 0" 
18' 2" 


26' 0" 
22' 9" 
18' 9" 


26' 9" 
23' 5" 
19' 4" 


2X14 


12 
16 
24 


20' 0" 
18' 4" 
16' 3" 


21' 2" 
19' 6" 
17' 3" 


22' 6" 
20' 6" 
18' 1" 


23' 5" 
21' 5" 
18' 11" 


21' 11" 
19' 3" 
15' 11" 


23' 2" 
20' 3" 
16' 9" 


24' 3" 
21' 3" 
17' 7" 


25' 4" 
22' 3" 
18' 5" 


26' 4" 
23' 2" 
19' 2" 


27' 4" 
24' 0" 
19' 10" 


28' 4" 
24' 10" 
20' 7" 


29' 4" 
25' 8" 
21' 3" 


30' 0" 
26' 6" 
21' 11" 


27' 3" 
22' 6" 


3X 6 


12 
16 
24 


9' 11" 
9' 1" 
7' 11" 


10' 6" 
9' 8" 
8' 5" 


11' 2" 
10' 2" 
8' 11" 


11' 8" 
10' 8" 
9' 4" 


11' 10" 
10' 4" 
8' 6" 


12' 5" 
10' 11" 
8' 11" 


13' 1" 
11' 5" 
9' 5" 


13' 8" 
11' 11" 
9' 9" 


14' 3" 
12' 5" 
10' 3" 


14' 9" 
12' 10" 
10' 8" 


15' 3" 
13' 4" 
11' 0" 


15' 9" 
13' 9" 
11' 4" 


16' 3" 
14' 3" 
11' 9" 


16' 9" 
14' 9" 
12' 0" 


3X 8 


12 
16 
24 


13' 1" 
12' 0" 
10' 8" 


13' 11" 
12' 9" 
11' 3" 


14' 8" 
13' 5" 
11' 10" 


15' 4" 
14' 0" 
12' 4" 


15' 7" 
13' 8" 
11' 3" 


16' 5" 
14' 5" 
11' 10" 


17' 3" 
15' 1" 
12' 5" 


18' 0" 
15' 9" 
13' 0" 


18' 9" 
16' 5" 
13' 7" 


19' 5" 
17' 0" 
14' 1" 


20' 1" 
17' 8" 
14' 7" 


20' 9" 
18' 3" 
15' 0" 


21' 5" 
18' 9" 
15' 6" 


22' 0" 
19' 4" 
15' 11" 


3X10 


12 
16 
24 


16' 5" 
15' 1" 
13' 4" 


17' 6" 
16' 1" 
14' 2" 


18' 5" 
16' 11" 
14' 11" 


19' 3" 
17' 8" 
15' 7" 


19' 6" 
17' 2" 
14' 3" 


20' 7" 
18' 1" 
15' 0" 


21' 7" 
18' 11" 
15' 9" 


22' 6" 
19' 9" 
16' 5" 


23' 3" 
20' 8" 
17' 1" 


24' 4" 
21' 4" 
17' 9" 


25' 2" 
22' 2" 
18' 4" 


26' 0" 
22' 10" 
18' 11" 


26' 9" 
23' 7" 
19' 6" 


27' 7" 
24' 3" 
20' 1" 


3X12 


12 
16 

24 


19' 9" 
18' 2" 
16' 1" 


20' 11" 
19' 4" 
17' 1" 


22' 1" 
20' 4" 
18' 0" 


23' 1" 
21' 3" 
18' 9" 


23' 4" 
20' 6" 
17' 1" 


24' 7" 
21' 8" 
18' 0" 


25' 9" 
22' 9" 
18' 10" 


26' 11" 
23' 9" 
19' 9" 


28' 0" 
24' 8" 
20' 6" 


29' 1" 
25' 8" 
21' 4" 


30' 0" 
26' 6" 
22' 1" 


27' 5" 
22' 9" 


28' 3" 
23' 6" 


29' 1" 
24' 2" 


3X14 


12 
16 

24 


23' 1" 
21' 3" 
18' 9" 


24' 5" 
22' 6" 
20' 0" 


25' 9" 
23' 9" 
21' 0" 


26' 11" 
24' 10" 
22' 1" 


27' 0" 
23' 11" 
19' 11" 


28' 6" 
25' 2" 
21' 0" 


30' 0" 
26' 5" 
22' 0" 


27' 7" 
23' 0" 


28' 9" 
23' 11" 


29' 9" 
24' 10" 


30' 0" 
25' 9" 


26' 7" 


27' 5" 


28' 2" 


Noff.- When limited by deflection, the lengths are based on: Maximum allowable deflection of 1/360 of span length. Modulus of elas- 
ticity as noted for E. When determined by bending strength on the piece: Allowable stress in extreme fiber in bending as noted for /. 

Dead load: Weight of joist. Weight of lath and plaster ceilinf? Live load: 40 lb. per sq. ft. of floor area with plastered ceiling, 
(10 lb. per sq. ft.). Double thickness of flooring (5 lb. per sq. ft.). or 50 lb. per sq. ft. with ceiling unplastered. 


GROSS BRIDGING FOR FLOOR AND CEILING JOISTS 


Number of rows 


1 


2 


3 


Span 


From 6' 0" to 10' 0" 


From 10' 0" to 20' 0" 


Over 20' 0" 


Sweet's 


PAGE 7 


Continued on next page 


B2588 


Chicago Mill and Lumber Corporation 


WALL 


BALLOON FRAME 


BRACED FRAME 


£i £ VA TION OF FXAM/m 


SECTION THRU 
miSH£0 WALL 


WESTERN FRAME 


)NEATH£/iWOOO SHeATWNG 


1^ 


-iP/Re STOPS] 


-RI650N 6CAR.O 


HEAT t 

'■ i{/K£. STOPS 


S£CTfOf^ TNJIC 
£XT£R/Ofl. WALL 


SECTION THRU 
/AJT6/Z/0/Z PAR.TIT/ON 


BALLOON FRAME 
At Second Floor 


/W£AIti££M20P SH^ATH/N9 
5TUDOIN& 


Fifie. stops] 


-ROaSH FLOOR. 


-NEAT 6 
FIK.E STOPS 


S£CT/ON THRU 
£\T£RlOR. WALL 


SECT/ ON THRU 
INTER/OfiL PART/T/OH 


BRACED FRAME 
At Second Floor 


- STUDOlN(» 

-SILL 


ROUSH FLOOtt, 


3£CnOA^ THRU 
aXTEftfO/l. WALL 


SECTION THRU 
/NTEV.IOR. PART/T/ON 


WESTERN FRAME 
At Second Floor 


LATH fl/PP£0 
TO 5/ZF. 


WEATHER.WOOD 

STANDARD FRAME 
^-in. Weatherwood Lath 


EXCLUSIVE WEATHER- 
WOOD LATH JOINT 
l^-in. Weatherwood Sheathing (Longitudinal) F. S. D. 


WEATHE/IWOOD 

STANDARD FRAME 
1-in. Weatherwood Lath 
1-in. Weatherwood Sheathing 


RECOMMENDED CONSTRUCTION DETAILS 


Sweet's 


PAGE 8 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2589 


(E) EFFECTIVE INSULATION THICKNESS AND LOCATION 


(El) Heat Flow 

Loss of heat occurs through the heat flow from a 
substance of high temperature to one of lower tempera- 
ture. Unless some barrier, such as insulation which 
definitely resists heat transmission, is interposed be- 
tween the two elements of different temperatures, the 
heat flow is rapid until the temperatures equalize. 

The insulating efficiency of a material varies di- 
rectly in proportion to its thickness — ^thus, twice the 
thickness, twice the efficiency and conversely, one-half 
the thickness, one-half the efficiency. This must be 
taken into consideration in comparing two materials 
even if they have the same thermal conductivity on the 
usual 1-in. thickness. 

(E2) Roafs 

As set forth in (D5) page 7, from 55 to 60 per 
cent of the heat loss in uninsulated dwellings occurs 
through the exterior walls and roofs. Of this loss, the 
greatest proportion is through the roof or top story 
ceiling, due to the fact that heated air rises and that 
the roof represents the greatest single area. 

Again, in summer the sun's rays fall more directly 
and with the greatest intensity on the roof, in conse- 
quence of which the top story of the uninsulated house 
is a source of great discomfort during hot weather. 

To be effective, a minimum of 1-in. thickness of 
insulation added to the usual standard construction 
should be installed in the roof or top story ceiling de- 
pending on whether there is an attic or whether the 
attic space is used for living quarters. 

(E3) Exterior Walls 

While a lesser proportion of heat loss occurs 
through the exterior walls as compared with roofs, this 
loss is sufficient to require a minimum of I/2 thick- 
ness of insulation (such as Weatherwood Insulating 
Lath) added to the usual standard frame, wood sheathed 
construction to provide any definite economy in fuel 
consumption. See particularly (E4). 

The infiltration of air through masonry walls has 
been definitely established and has now become a factor 
in heating design. Due to this fact, it is quite as 
essential that masonry walls be insulated as frame walls. 
At least ^-in. thick insulation is desirable. Weather- 
wood Lath applied to furring strips is an economical 
method. 

(E4) Weatherwood as Sheathing and Roof Boarding 

When an insulating material is substituted for some 
other material, such as Weatherwood Sheathing for 
wood sheathing, no great insulation benefits accrue un- 
less a sufficient thickness of the insulating material is 
used. 

Weatherwood has a thermal conductivity of .32 
B.t.u.'s per hour, per sq. ft., per inch thickness, or .64 
B.t.u.'s per i^^-inch thickness (see (Bl) page 2). Stated 
in terms of heat resistance, half-inch Weatherwood has 
a resistance of L56 degrees (the reciprocal of its con- 
ductivity). Ordinary sheathing lumber has a thermal 
conductivity of .80 B.t.u.'s per sq. ft., per inch thick- 


ness or per ||-in. thickness (as ordinarily used), a 
thermal conductivity of .98 B.t.u.'s per sq. ft., per de- 
gree F., per hour and a resistance of L02 degrees. In 
other words, Weatherwood as a sheathing is approxi- 
mately 55% more effective in the i/2-in. thickness than 
the standard if-in. wood sheathing. 

Despite this fact, and even though there is no insu- 
lating board with higher efficiency than Weatherwood, 
it should be recognized that used alone as sheathing 
without additional insulation on the interior, such as 
Weatherwood Insulating Lath, the %-in. thickness of 
Weatherwood Sheathing is not sufficient to produce a 
truly economical wall from a heat loss standpoint. The 
same considerations apply where Weatherwood is sub- 
stituted for roof boarding. 

Therefore, wherever Weatherwood insulating board 
is substituted for wood sheathing on walls, and addi- 
tional insulation is not included on the interior, always 
use the 1-in. thick Weatherwood. 

Where Weatherwood is substituted for roof board- 
ing always use the 1-in. thickness and add at least a 
i/2-in. thickness on the interior primarily as insulation 
(see (C8) page 4), as an interior finish (see (C5) page 
4) or as insulating lath (see (C4) page 4). 

(E5) Insulating the Interior 

The effectiveness and fuel economy of interior 
insulation is quite universally overlooked. 

It is a well established fact that it is fuel economy 
to maintain the same temperature in the home both day 
and night. More fuel is consumed in raising the tem- 
perature of a cold house in the morning than is con- 
sumed in maintaining the uniform temperature because 
of the inefficiency of intermittent firing. 

It is also a fact that the average person sleeps in 
a cold bedroom. The radiator is turned off and the 
window is opened, which virtually during this 8-hour 
period (one-third of the heating day) converts large 
areas of the second story into unheated space similar 
to an unheated attic. The heat loss from the first 
story through the first story ceiling or second story 
floor almost compares with the heat loss through 
the uninsulated top floor ceiling or roof (see (E2) 
page 9). 

If the first story floor over a cold basement, and 
the first story ceiling (second story floor) are insulated 
and the partitions between heated halls, bathrooms, 
dressing rooms and bedrooms are likewise insulated, the 
greatest fuel economies are possible and greater com- 
fort is assured. 

A simple method of accomplishing these desirable 
features is the use throughout the dwelling of Weather- 
wood Insulating Lath on all interior partitions and ceil- 
ings. In floor construction the use of 1-in. Weather- 
wood lath or the i^-in. lath on the ceiling with the addi- 
tion of 14-in. insulation elsewhere in the construction is 
recommended. 

This same insulation which makes it possible to 
create a cold area as a unit without heat loss in the rest 
of the house, also adds a great comfort in sound insula- 
tion as well. An appreciably less amount of sound will 
be transmitted from one floor to the next and from one 
room to those adjoining. 


Sweet's 


PAGE 9 


Continued on next page 


B2590 


Chicago Mill and Lumber Corporation 


(F) WEATHERWOOD AS SHEATHING AND ROOF BOARDING 


(Fl) Use 

(Fla) Walls — Under wood siding, shingles, stucco or 
masonry veneer. 

(Fib) Roofs — Under shingles, slate, tile or similar rigid 
roof units which may be laid over wood furring strips. 

(F2) Sizes 

Full 1/2 in. and 1 in. thick by 4 ft. wide by 8, 9, 10 or 12 ft. 
long. 

(F3) Advantages 

(F3a) Low Thermal Conductivity — It is an excellent 
insulator when used in the proper thickness. (See (Bl) page 2 
and (E4) page 9.) 

(F3b) Strength — One-half inch thick, it is approximately 
twice as strong (bracing against distortion) as horizontal wood 
sheathing. (See (B6) page 3.) 

(F3c) Moistureproof — Chemically treated, it is highly 
moisture and decay resistive. It requires no waterproof paper 
over it for protection. (See (B5) page 3.) 

(F3d) No Open Joints — The large boards join only over 
framing members. Weatherwood provides a continuous, 
unbroken, uniform surface which, without the aid of water- 
proof building paper, successfully prevents air infiltra- 
tion. 

(F3e) Expansion or Contraction — Weatherwood under 
all conditions remains as originally applied. It does not expand 
or contract appreciably. 

(F4) SPECIFICATIONS 

Note: Notes are explanatory or advisory only and should 
not be included in the specifications. 

Note: Select and include only those clauses which apply 
to the particular work. Words in bracketed italics are 
selective. 


(F4a) Work Included 

Note: Here list and locate definitely the wall and roof 
areas to be covered. If both V2-in. and 1-in. thickness are 
used, list separately and the respective locations or areas 
covered. 

Note: For selection of thickness see division (E) page 9 
and particularly (E4). 


(F4b) Material 

(Sheathing) (and) (roof boarding) shall be Weatherwood 
as made by Chicago Mill and Lumber Corporation, 111 West 
Washington Street, Chicago. Boards shall be full (V2 in.) 
(and) (1 in.) thick (as above designated), 4 ft. wide by 8, 9, 
10 or 12 ft. long as best adapted. 


(F4c) Application 

(F4cl) General — Continuity of insulation is imperative. 
Apply Weatherwood with the length parallel with the framing 
members. Where possible boards shall be of sufficient length 
to completely span between sills and plates or other structural 
members. Where end joints are necessary these shall only 


be made centered over 2x4-in. headers cut in between fram- 
ing members. Side joints shall center over framing mem- 
bers. 

(F4c2) Spacing — Weatherwood boards shall be spaced 
% in. apart at all edges. Bring the Weatherwood in close con- 
tact with window and door frames and trim. 

(F4c3) Nails— 

(a) Use 6d common nails for %-in. thick Weatherwood. 

(b) Use 8d common nails for 1-in. thick Weatherwood. 
Note: Large headed nails are unnecessary. 

(F4c4) Nailing — At all edges, space nails 3 in. apart on 
centers and Mj in. from the edge. On intermediate framing 
members, space nails 6 in. apart on centers. First nail Weather- 
wood to intermediate studs and then nail the edges. 

(F5) SUPPLEMENTARY PROVISIONS 

Note: Provide for the folloiving in other specification 
divisions. 

Note: Weatherivood is not a nailing base. 

( F5a ) Construction 

Follow the recommendations of the Building Code Com- 
mittee of the U. S. Department of Commerce and the National 
Lumber Manufacturers Association. (See division (D) pages 
4, 6, 7 and 8.) 

(F5b) Wood Siding 

All joints shall butt over the center of a stud. 

(F5c) Furring Strips 

Provide lx2-in. furring strips properly spaced over 
Weatherwood to take shingles, slate, tile and similar wall and 
roof covering. Nails shall be sufficiently long to pass through 
the furring and Weatherwood and penetrate the framing mem- 
bers at least 1 in. 

(F5d) Stucco Base 

Stucco must be reinforced with self-furring galvanized 
wire or expanded metal exterior stucco lath secured to studs 
with nails sufficiently long to pass through the Weatherwood 
and penetrate the stud at least 1 in. 

(F5e) Masonry Veneer Ties 

Provide masonry tics at each stud spaced 16 in. apart ver- 
tically. Nails shall be sufficiently long to pass through the 
Weatherwood and penetrate the stud at least 1 in. 

(F5f) Frame Furring, etc. 

Provide in accordance with the details window and door 
frame furring strips to compensate for the thickness of 
Weatherwood. 

Note: JVe adi'ocate ivide outside blind stops in frame 
construction. If, however, these are omitted, provide thai 
the inside of the outside casings be lined with beveled strips 
of Weatherwood. See particularly (D5) page 7 and de- 
tails on page 8. 


(G) WEATHERWOOD INSULATING LATH 


(Gl) Use 

As an insulating plaster base. 

(G2) Size 

Full V2 in. and full 1 in. thick by 18x48 in. Half-inch 
thickness wrapped 12 pieces to the package, 72 sq. ft. One- 
inch thickness wrapped 6 pieces to the package, 36 sq. ft. 
Weight, 650 lb. per 1000 sq ft., V2 in. thick. 

( G3 ) Advantages 

(G3a) Low Thermal Conductivity — It is an excellent 
insulator when used in the proper thickness. (See (Bl) page 


2 and (E) page 9, particularly (E4)). 

(G3b) The Exclusive Weatherwood Lath Joint—It has 

always been known that a continuous surface over which plas- 
ter might be applied would provide the best possible base. It 
is, however, impracticable to do this and at the same time 
eliminate the tendency of such a surface to expand and con- 
tract excessively causing buckling. 

Previous plaster bases have always left horizontal joints 
of greater or less width into which the plaster was forced. As 
the units of such a plaster base dry out and shrink, these joints 
open up pulling away from the plaster which worked into the 
joints leaving a weak and fragile plaster joint to withstand all 
strains and vibrations. 


Sweet's 


PAGE 10 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2591 


The tongue and groove Weatherwood Lath joint (see de- 
tails on page 8) is an exclusive Weatherwood feature and 
alone in its ability to form a tight, strong joint along the hori- 
zontal or long edge (spanning the space between framing mem- 
bers) into which plaster cannot be forced. It is so designed 
that when the wet plaster is troweled over the board, and the 
slight normal expansion takes place, the beveled profile of the 
joint permits this expansion to take place by the compression 
of the fibers at the joint. As the plaster dries, the resilient 
Weatherwood fibers gradually resume their original position 
and since they cannot contract to a condition smaller than the 
original one, there is no opening of joints along these edges. 
Practically a homogeneous surface is therefore provided as a 
plaster base, resulting in the elimination of strains at the joints 
which would tend to crack the plaster. 

The tongue and groove joints also eliminate the springing 
of the board out of its true plane at these unsupported joints 
when the scratch and brown coats of plaster are being troweled 
on. This often occurred with earlier forms of lath boards 
tending to develop hair line cracks through the set and partially 
dry scratch coat when the brown coat is being applied and 
before the set plaster thickness is sufficient to withstand the 
strain. 

(G3c) Strong Plaster Bond — Weatherwood provides an 
especially strong bond between the base and plaster. (See 
(B7) page 3.) 

(G3d) Strength — While not of primary importance, the 
strength of bracing against distortion when applied to frame 
construction is an advantage, especially when applied to interior 
l)artitions. (See (B6) page 3.) 

(G3e) Moistureproof — Aloisture cannot pass through 
Weatherwood Lathe (see (B5) page 3). This characteristic of 
Weatherwood protects the frame from the moisture of the 
plaster, which passes into the interior of the building to be 
carried away by adequate ventilation. 

Since the plaster thickness is reduced to a uniform V2 in., 
less moisture must be driven off during the plastering operation 
than is the case with open-mesh types of lath which require a 
much thicker body of plaster. 

(G3f ) No Lath or Joint Marks — The exclusive Weather- 
wood Lath tight tongue and groove joint eliminates the so- 
called lath or joint marks appearing on the plaster surface due 
to condensation of moisture and collection of dirt along the 
open joints of the plaster base and which require frequent 
cleaning and redecoration. 

(G3g) Easily Handled — The convenient size, 18x48 in., 
provides an easily handled unit, rapidly erected. Can be car- 
ried into any space a man can work. Is easily scored and cut 
with a lathing hatchet where necessary to fill out at angles, 
corners, etc. 

(G4) SPECIFICATIONS 

Note: Notes are explanatory or advisory only and should 
not be included in the specifications. 

Note: Select and include only those clauses ivhich apply 
to the particular work. Words in bracketed italics are 
selective. 

(G4a) Work Included 

Note: Here list and locate definitely the zvall and ceiling 
areas to be covered. If both Vi-in. and 1-in. thickness are 
used list separately and the respective locations or areas 
covered. 

Note: For selection of thickness see division (E) page 9 
and particularly (E4) and (E5). 

(G4b) Material 

Plaster base shall be Weatherwood Insulating Lath as 
made by Chicago Mill and Lumber Corporation, 111 West 
Washington Street, Chicago. Units shall be full ("Mj in.) (and) 
(1 in.) thick (as designated above), 18 in. wide by 48 in. long. 

(G4c) Application 

(G4cl) General — Do not moisten lath before application. 
Apply Weatherwood Lath, rough or textured side exposed and 
tongue up, with the length at right angles to the framing (or 
furring) members. End joints shall center over framing mem- 
ber^. Stagger end joints in successive courses on all walls and 
ceilings; likewise stagger end joints at juncture of walls and 
ceilings. 

(G4c2) Spacing — Tongue and groove joints shall be 
brought tight in moderate contact. Units shall be spaced % in. 
apart at ends. 

(G4c3) Nails— 

(a) Use 4d common, blued or box nails, for V^-in. thick 
Weatherwood Lath. 


(b) Use 6d common, blued or box nails, for 1-in. thick 

Weatherwood Lath. 

Note: Large headed nails are unnecessary. 

(G4c4) Nailing — Space nails SV2 in. apart on centers set 

V'2 in. from the edges. First nail to intermediate framing (or 

furring) members and then at ends. Secure long edges at 

angles of walls and ceilings, spacing nails SV2 in. on centers 

and not more than V2 in. from the edge. 

(G4c5) Prevention of Condensation — In cold weather 

apply Weatherwood to exterior studs (furring) (rafters), etc. 

before temporary heat is applied. 

Note: Because Weatherwood Lath does not permit pas- 
sage of moisture, heating before lining the exterior cold 
ivalls, etc., results in a condensation of moisture from the 
zvarm, moist air on the inside of the sheathing and fram- 
ing members. This originally forms as frost, which melts 
and must be absorbed gradually by the sheathing and 
frame, since it cannot pass the W eatherwood barrier to be 
carried off by the air. Weatherwood applied before heat 
insulates the zvarm, moist air from the cold exterior walls 
and eliminates this possibility of condensation. 

(G5) SUPPLEMENTARY PROVISIONS 

Note: Provide for the following in other specification 
divisions. 

( G5a ) Construction 

Follow the recommendations of the Building Code Com- 
mittee of the U. S. Department of Commerce and the National 
Lumber Manufacturers Association. See Division (D) pages 
4, 6, 7 and 8. 

(G5b) Furring 

Fur all exterior masonry walls to receive Weatherwood 
with (Lv2 in.) (specify) furring strips, accurately shimmed to 
a true, level plane, set 16 in. on centers. Substantially secured 
to the masonry. 

(G5c) Grounds 

Furnish and erect, substantially secured to framing mem- 
bers through the Weatherwood Lath, full %-in. grounds on 
exterior frame walls and full V2-in. grounds elsewhere. 

Note: Full V^-in. thickness of plaster should be used over 
IVeatherzvood Lath. Where stock window and door frames 
are used they provide for %-in. thickness for lath and 
plaster, therefore on exterior frame zvalls, which are 
usually of less area due to zvindow and door openings, a 
%-in. thickness may be used. If special frames are de- 
tailed, provide for full V2-in. thickness of plaster over the 
lath. 

(G5d) Plastering 

(G5dl) Caution — Do not wet Weatherwood Lath before 
applying plaster. 

(G5d2) Comerite — Apply metal lath "cornerite" strips 
over Weatherwood Lath at all re-entrant angles and all corners 
not protected with corner beads. 

(G5d3) Plaster — Use gypsum cement or gypsum wood 
fiber plasters. 

(G5d4) Thickness — Full % in. thick on exterior frame 
wall, elsewhere full V2 in. thick, flush with grounds. 
Note: See (G5b) above. 

(G5d5) Application — Apply in three (3) coats in accord- 
ance with the plaster manufacturer's specification. Surfaces 
shall be rodded to a true plane. All corners and angles shall 
be plumb and true. Wherever necessary and particularly on 
ceilings, provide plaster screeds to insure an even and uniform 
plaster thickness. 

Note: The maintaining of a uniform and sufficient plaster 
thickness over a fibrous or board plaster base such as 
Weatherzvood, and especially on ceilings, cannot be too 
strongly stressed if permanent, satisfactory results are to 
be expected. Too frequently a weak, thin plaster coat, 
inadequate to withstand the usual strains of building settle- 
ment, shrinkage and vibration, results in plaster cracks 
which react on even the best of plaster bases. 
(G5d6) Ventilation — Provide adequate ventilation for the 
proper drying of the plaster work. 

Note: Due to the moistureproof characteristics of 
Weatherzvood Lath, all moisture emanating from the plas- 
tering operation must be carried off by the air coming in 
contact zvith the exposed surface. Particular attention to 
proper ventilation is necessary. 


Sweet's 


PAGE 11 


Continued on next page 


B2592 


Chicago Mill and Lumber Corporation 


(H) WEATHERWOOD 


(HI) Introduction 

Generally speaking, we realize that Weatherwood as inte- 
rior finish (without interior plaster) has but hmited architec- 
tural adaptability. There are, however, many applications, such 
as acoustical correction, finish for basement, amusement rooms, 
garages, attic rooms, storerooms, etc., where its good appear- 
ance coupled with its value as insulation make it highly desir- 
able. It is particularly practical in alteration work. 

It takes stains, paints, plastic paints and wall paper with 
admirable results. The foundation to which Weatherwood is 
applied, and the care with which it and the finish is applied is 
obviously reflected in its final satisfactory appearance. 

(H2) Use 

As an unplastered interior wall and ceiling finish, in its 
natural state (unfinished), stained, painted or covered with 
plastic paint or with wall paper. 

Unfinished or finished with stains it has a decided value 
as an interior lining for sound absorption in halls, gymnasiums, 
churches, schools, etc. When used for acoustical correction it 
should not be painted. 

(H3) Sizes 

(H3a) When Exposed (Natural, Stained or Painted)— 

Full ¥2 in. and 1 in. thick (depending on insulation require- 
ments) by 4 ft. wide by 8, 9, 10 and 12 ft. long. Where design 
dictates, smaller units may be used. 

(H3b) Finished with Plastic Paint or Wall Paper— 
Weatherwood or Weatherwood Insulating Lath, full Mj in. 
and 1 in. thick (depending on insulation requirements). 

(H4) Advantages 

(H4a) Low Thermal Conductivity — It is an excellent 
insulator when used in the proper thickness. (See (Bl) page 
2 and (E) page 9.) 

(H4b) Good Appearance — One side is finished in a uni- 
form scmirough, textured finish — the other side smooth. Either 
side may be selected for exposure. The natural color is an 
attractive cream-white. Joints may be exposed, finished square 
or beveled or they may be covered with wood or Weatherwood 
battens. 

(H4c) Strength— It is strong and durable. (See (B3) 
page 3.) ^ 

(H4d) Moistureproof — It is highly moisture resistant. 
(See (B5) page 3.) 

(H4e) Fire Resistance — It is not a fire hazard. (See 
(B8) page 3.) _ 

(H4f) Continuity — It is a perfect, continuous seal against 
air infiltration. (See (BIO) page 4.) 

(H4g) Cleans Easily — In its natural state or stained it 
is easily cleaned with a stiff brush or with a vacuum cleaner. 


(H5) SPECIFICATIONS 

Note: Notes are explanatory or advisory only and should 
not he included in the specifications. 

Note: Select and include only those clauses which apply 
to the particular zcork. Words in bracketed italics are 
selective. 

(H5a) Work Included 

Note: Here list and locate definitely the zvall and ceiling 
areas to be covered. If tzvo types of finish — namely 

(1) exposed zvith natural stained or painted finish and 

(2) finished zvith plastic paint or zvall paper or tzvo thick- 
nesses are required, list separately and the respective loca- 
tions or areas covered. 

(H5b) Material 

(H5bl) Wall (and ceiling) finish shall be (Weatherzvood 
Insulation Boards) (and) (Weatherzvood Insulating Lath) as 
made by Chicago AIill and Lumber Corporation, 111 West 
Washington Street, Chicago. 

Note: Specify ''Weatherzvood Insulation Boards'* zvhere 
exposed zvith natural, stained or painted finish. Specify 
Weatherzvood Insulating Lath zvhere finished zvith plastic 
paint or zvall paper. 


Sweet's 


AS INTERIOR FINISH 


(H5b2) Size shall be (V2 in.) (and) (1 in.) thick by 4 ft. 
by 8, 9, 10 or 12 ft. long or units cut from the board in panels 
of symmetrically disposed sizes to conform with the detail 
drawings. 

Note: Use clause above for natural, stained or painted 
finish. Select the thickness required for insulation value. 
(H5b3) Size shall be (V2 in.) (and) (1 in.) thick by 18x48 
in., standard Weatherwood Insulating Lath. 

(H5c) Application 

(H5cl) General— 

(a) Weatherwood Boards — 
Note: Same as (F4cl) page 10. 

(b) Weatherwood Lath — 
Note: Same as (G4cl) page 11. 
(H5c2) Spacing— 

(a) For Weatherwood Boards — 
Note: Same as (F4c2) page 10. 

(b) For Weatherwood Lath — 
Note: Same as (G4c2) page 11. 

(H5c3) Finishing Joints of Weatherwood Boards— 

(a) Exposed Joints — Neatly finish the exposed joint edges 
with sandpaper (square) (rounded) (beveled) as detailed. 

(b) Battens — Form Weatherwood joint battens of widths 
detailed with edges neatly sandpapered (square) (round) 
(beveled). Fit battens neatly at all intersections or at points in 
contact with other trim. Secure battens with finishing nails as 
specified in (a) (H5c5). 

(H5c4) Nails— 

(a) For Weatherwood Boards — Use 2-in. finishing nails. 

(b) For Weatherwood Lath — 
Note: Same as (G4c3) page 11. 
(H5c5) Nailing— 

(a) For Weatherwood Boards — Nails shall be driven at 
an angle with heads neatly set below the surface. 

Note: Continue same as (G4c4) page 11. 

(b) For Weatherwood Lath — 
Note: Same as (F4c4) page 10. 

(H6) SUPPLEMENTARY SPECIFICATION 
PROVISIONS— FINISHING, ETC. 

Note: Provide for the follozving in other specification 
diz'isions. 

Note: Weatherzvood is not a nailing base. 

( H6a ) Construction 

Note: Same as (F5a) page 10. 

(H6b) Furring 

Note: Same as (G5b) page 11. 

(H6c) Finish 

Note: W^eatherzuood boards may be left natural, or fin- 
ished zvith stain or paint. Weatherzvood lath may be fin- 
ished zvith plastic paint or zvall paper. 
(H6cl) Natural — When a harder surface is desired, color- 
less sizing, such as water size, may be applied. 

(H6c2) Stain — Weatherwood takes water, alcohol or other 
types of stain admirably, either in single tones, panels or stencil 
design. 

Note: Where used as acoustical correction, use stain only. 
Paint fills the pores and materially reduces the acoustical 
efficiency. 

(H6c3) Paint — Size thoroughly with water, glue or oil 
size. Apply paint in accordance with the manufacturer's direc- 
tions. 

(H6c4) Plastic Paint — Plastic paints do not provide 
satisfactory protection from excessive moisture. Where a 
building is highly humidified at times, the use of plastic paint 
over Weatherwood is not recommended, since it takes but 
slight shrinkage strain to form cracks in the thin plastic paint 
layer. 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2593 


In no case is a single coat of plastic paint over Weather- 
wood recommended. Such a thin coat will not adequately cover 
all irregularities and joints and it provides no protection against 
the usual strains of service. Therefore, use two (2) coats of 
plastic paint on Wcatherwood. 

Joints should be filled with the joint filler specified by the 
plastic paint manufacturer and covered with cloth or wire 
screen tape as specified. 

Depending on the type of plastic paint, size may or may 


not be required. Apply plastic paint in accordance with the 
manufacturer's directions. 

(H6c5) Wall Paper— First line the wall over the Weather- 
wood Lath with iy2-lb. unsaturated building felt neatly applied 
with wall paper paste in the same manner as wall paper. The 
joints should be accurately trimmed to butt. Over the felt 
apply the wall paper in the customary manner. Careful work- 
manship will furnish a highly satisfactory finish almost com- 
parable with that of a plastered wall. 


(J) WEATHERWOOD 

(Jl) Use 

While generally speaking of limited architectural adapta- 
bility, Wcatherwood as exterior finish has many applications, 
especially when its moistureproof insulation value is considered. 

It is particularly adapted to the lighter, less permanent 
construction where cost is a prime factor, and especially for 
buildings of but one story, such as small dwellings, garages, 
summer cottages, portable temporary schools, etc. It is an ideal 
exterior finish for such temporary construction buildings as 
offices and tool and material storehouses. 

(J2) Sizes 

Full Mj in. and 1 in. (depending on insulation require- 
ments) thick by 4 ft. wide by 8, 9, 10 or 12 ft. long. 

( J3 ) Advantages 

The advantages as set forth in (F3) page 10 for Weather- 
wood Sheathing and Roof Boarding apply equally to Weather- 
wood Exterior Finish. 


AS EXTERIOR FINISH 

( J4 ) Specifications 

(J4a) Construction Provisions — Follow the recommenda- 
tions of the Building Code Committee of the U. S. Department 
of Commerce and the National Lumber Manufacturers Asso- 
ciation. (See division (D) pages 4, 6, 7 and 8.) 

(J4b) Application, etc. — The specifications (F4) page 10 
for Wcatherwood Sheathing apply likewise to Wcatherwood 
Exterior Finish. 

(J4c) Painting — Size thoroughly with a dependable water, 
glue or oil size. Finish with two (2) coats of any good exte- 
rior house paint applied in accordance with the manufacturer's 
directions. 

Note: The painting of Wcatherwood surfaces should he 
done before the application of the joint battens, trim, 
etc. 

(J4d) Joint Battens, Trim, etc. — Cover all joints between 
the Wcatherwood boards and all edges with wood batten Strips 
or exterior wood trim, secured through the Wcatherwood to 
the framing members. 


(K) WEATHERWOOD USED AS ADDED INSULATION 


(Kl) Use 

Note: See separate division (L) page 14 for Weatherwood 

Insulation over roof decks of ivood, concrete, steel, tile, etc. 

(Kla) Over Exterior Wood Sheathing— Covered by 
additional exterior finish such as wood siding, shingles, stucco, 
masonry, veneer, etc. 

(Klb) Under or Over Wood Roof Boarding— Covered 
by shingles or other roofing materials. For rigid roofing units, 
such as wood shingles, slate, etc., furring strips are recom- 
mended if insulation is placed over roof boarding. Generally 
speaking, if placed under roof boarding directly on the rafters 
the position closer to the heat source is preferable, and 
obviously any type of roofing applicable over wood roof board- 
ing may be used. 

(Klc) Over the Interior of Framing Members — Over 
studs, furring, joists, rafters, etc., with plaster base furred over 
or placed immediately over the Weatherwood. 

(Kid) Between Rough and Finished Floors. 

(K2) Sizes 

Full 1/2 in. and 1 in. thick by 4 ft. wide by 8, 9, 10 or 12 ft. 
long. 

(K3) Advantages 

(K3a) Low Thermal Conductivity — It is an excellent 
insulator. (See (Bl) page 2.) 

(K3b) Moistureproof — Chemically treated it is highly 
moisture and decay resistive, thus permanently of insulation 
value. (See (B5) page 3.) 

(K3c) Continuity — No Open Joints — When properly 
applied, it provides a continuous unbroken surface which suc- 
cessfully prevents air infiltration. (See (B13) page 4.) 

(K3d) Non-compressibility — Retains its firm, non-com- 
pressible form when placed under other materials, thus main- 
taining its original insulating value. (See (B12) page 4.) 

(K3e) Rugged Strength — Does not tear or break in appli- 
cation. (See (B6) page 3.) 

(K3f) Decreases Fire Hazard — Permits the proper loca- 
tion of the recommended fire stops in standard construction 
and in itself is not a fire hazard. (See (B8) page 3.) 

(K3g) Easy to Install — Light and rigid, its conveniently 
sized units are easily and economically installed. 


(K4) SPECIFICATIONS 

Note: Notes are explanatory or advisory only and should 
not be included in the specifications. 

Note: Select and include only those clauses which apply to 
the particular work, ll 'ords in bracketed italics are selective. 

(K4a) Work Included 

Note: Here list and locate definitely the insulation to be 
installed. If both V2 in. and 1-in. thicknesses are used, list 
separately and the respective locations or areas covered. 
Note: For selection of thickness, see division (E) page 9. 

(K4b) Material 

Insulation shall be Weatherwood as made by Chicago Mill 
AND Lumber Corporation, 111 West Washington Street, Chi- 
cago. Boards shall be full (V2. in.) (and) (1 in.) thick (as 
above designated), 4 ft. wide by 8, 9, 10 or 12 ft. long as best 
adapted. 

(K4c) Application 

(K4cl) General — Continuity of insulation is imperative. 
Apply Weatherwood with the length parallel with the framing 
members, smooth face exposed. Where possible, boards shall 
be of sufficient length to completely span between sills and 
plates or other structural members. Where end joints are 
necessary, these shall only be made centered oyer 2x4-in. 
headers cut in between framing members. Side joints shall 
center over framing members. 

(K4c2) Spacing— Weatherwood boards shall be spaced 
in. apart at all edges. Bring the Weatherwood in close con- 
tact with window and door frames and trim. 

(K4c3) Nails— 

(a) Use 6d common nails for ^/^-in. thick Weatherwood. 

(b) Use 8d common nails for 1-in. thick Weatherwood. 
Note: Large headed nails are unnecessary. 

(K4c4) Nailing — Space nails on edges and intermediate 
framing members 12 in. apart on centers. Nail to intermediate 
supports first and then nail edges approximately % in. from the 
edge. 

Note: Additional fastening is provided through the secur- 
ing of the usual covering materials. If advantage of the 
structural strength of Weatheriuood is desirable, nailing 
should be done in accordance with clause (F4c4) page 10 
instead of as above. 


Sweet's 


PAGE 13 


Continued on next page 


B2594 


Chicago Mill and Lumber Corporation 


(K4c5) Prevention of Condensation — 
Note: Same as (G4c5) page 11. 

(K5) SUPPLEMENTARY PROVISIONS 

Note: Provide for the following in other specification 
divisions. 

Note: Weatherwood is not a nailing base. 

(K5a) Construction 

Note: Same as (F5a) page 10. 

(K5b) Furring Strips 

Note: Same as (F5c) page 10 unless provision is made for 
securing the covering with nails sufficiently long to pass 


through the Weatherwood and penetrate the sheathing or 

roof boarding beneath. Also same as (G5b) page 10 zvhere 

required on the inside of masonry walls. 

(K5bl) Where Weatherwood is used over rough flooring, 
provide 1-in. x 2-in. stripping 16 in. over centers to receive 
nailing of finished flooring. 

(K5c) Stucco Base 

Note: Same as (F5d) page 10. 

(K5d) Masonry Veneer Ties 

Note: Same as (F5e) page 10 

(K5e) Frame Furring, etc. 

Note: Same as (F5f) page 10. 


(L) WEATHERWOOD INSULATION OVER ROOF DECKS 


(Ll) Use 

Over wood, concrete, tile, and steel roof decks covered with 
standard built-up roofing. Prevents heat loss and condensa- 
tion. Particularly adapted to industrial use. 


(L2) Size (Area of Units) 

Weatherwood Roof Insulation units for industrial pur- 
poses are made 2 ft. wide by 5 ft. long representing the ultimate 
development of experience with various sizes of units for roof 
insulation. It weighs approximately 625 lb. per V^-'m. thickness, 
per 1000 sq. ft. This size of the Weatherwood Roof Insulation 
unit is the correct medium between a unit which is too small 
or too large for economical and practical application. 

Insulation, due to its protection against low roof deck tem- 
peratures, reduces the contraction of the deck. This reduced 
contraction of a roof deck during cold weather is compensated 
for by a slight yielding of the fibers within each unit — some of 
this contraction and expansion is also taken up in the joints 
between the Weatherwood units. 

Note: The application of insulating material over a roof 
deck tends to decrease the amount of contraction and ex- 
pansion which takes place due to the extremes of tempera- 
ture. The difference in temperature from one extreme to 
the other in a roof deck covered zvith 1 in. of Weather- 
wood ranges between 40° and 90° — a total variance of only 
50° , zvhereas on an uninsulated deck, the temperature of the 
deck in extremes of temperature ranges betzveen zero and 
over 100° , a variance of over 100°. The resulting reduction 
in expansion and contraction strains is obvious. 


(L3) Thicknesses and Weights 

Weatherwood Roof Insulation units (2x5 ft.) are made in 
full V2-in. thickness or any multiple of V2 in. up to full 3-in. 
thickness. They weigh 60 lb. per square (100 sq. ft.) for V2-'m. 
thick, 130 lb. per square 1 in. thick, 195 lb. per square IV2 in. 
thick, 260 lb. per square 2 in. thick, 325 lb. per square 2V2 in. 
thick and 390 lb. per square 3 in. thick. 

Weatherwood unit thicknesses provide the greatest econ- 
omy in application, since the correct thickness for the greatest 
efficiency is applied in one operation — not built up by applying 
various layers of the V2-in. thickness on the job. 

Weatherwood Roof Insulation units are factory fabri- 
cated to the various thicknesses in the two methods described 
below : 

(L3a) Stapled Weatherwood — The various thicknesses 
are provided by stapling layers of V2-m. Weatherwood units 
(2x5 ft.) together with non-corroding metal clips. These clips 
are spaced close enough to secure rigidity and permanence. An 
advantage of stapling lies in the increased heat resistance. 

There is a definite resistance to heat flow called contact 
resistance at the point where two layers of material are placed 
together due to the two surfaces and the thin film of air be- 
tween them. Tests at the University of Minnesota by Prof. 
F. D. Rowley show that in a 2-in. block made by stapling four 
pieces of V2-in. material together, the total heat resistance of 
the block is increased slightly over 11% as compared to a solid 
2-in. thickness of the same material. 


The cross section of the clip is so small that even the most 
delicate instruments would show no appreciable heat loss by 
conduction through them from inside to outside surface. 

(L3b) Laminated Weatherwood — For special purposes or 
for those who prefer this type, Weatherwood Roof Insulation 
units (2x5 ft.) are made as a laminated board, wherein the 
V2-in. thicknesses are cemented together with a high grade 
waterproof cement. 

This cement is a development of years of research and 
experience by the Chicago Mill and Lumber Corporation in 
the manufacture of plywood. Its use provides added moisture 
sealing at each layer since the cement is even more moisture 
resistant than the Weatherwood. 

The method does not require hydraulic pressure, conse- 
quently there is no reduction of thickness or increased density 
of the Weatherwood Insulation with the resultant lessening of 
insulating efficiency. 

(L4) Advantages 

(L4a) Insulating Efficiency — Weatherwood Roof Insula- 
tion has a thermal conductivity of .32 B.t.u. per inch thickness 
per hour, per degree F., temperature difference, per square foot. 
(See (Bl) page 2 for supporting evidence.) 

(L4b) Thickness and Size of Units — The thicknesses of 
Weatherwood Roof Insulation are full V2 in. and multiples 
thereof up to full 3 in. (See (L3) opposite.) This should be 
borne in mind when making comparisons with other insulating 
materials. It is obvious that two boards having the same 
thermal conductivity on an inch basis would be unlike in actual 
efficiency if one were full V2 in. thick, the other of lesser thick- 
ness, or if one becomes compressed in application. (See 
(L4c) below.) 

The unit area (2x5 ft.) of Weatherwood Roof Insulation 
in the various thicknesses is not only the most practical from 
an installation economy point of view, but it is an area which 
experience has proven will best compensate for the expansion 
and contraction of the deck upon which it is laid. Under the 
most adverse conditions it prevents wrinkling and buckling of 
buih-up roofings laid over it. (See (L2) and (L3) on this 
page and (L4h) page 15.) 

(L4c) Non-compressibility — Resilience — Weatherwood 
compresses slightly under heavy pressures, but upon release of 
pressure immediately returns to its original thickness. This 
resilience protects against loss of efficiency and makes the 
covering material more resistant to abrasion and puncturing. 

(L4d) Bond — Weatherwood bonded to another substance 
by use of pitch or asphalt will withstand a pull of over 1200 lb. 
per sq. ft. This more than provides for the bonding require- 
ments of a roof insulating material. 

(L4e) Moisture Resistance — As explained in (A3c) page 
2 describing the manufacture of Weatherwood, moisture ab- 
sorption is extremely low because of the thorough weather- 
proofing of the individual fibers in making up the board. It is 
not only unaffected by moisture, but, in addition, has no capil- 
larity, so that even with moisture on the top surface of 
Weatherwood from leaks in roof covering, or beneath Weather- 
wood on roof deck from condensation, this moisture will not 
be drawn into the board (see (B5) page 3 for supporting evi- 
dence). This is an important factor in guarding against de- 
terioration of insulating material due to rot or decay. 


Sweet's 


PAGE 14 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2595 


(L4f) Tough — Easily Handled— Weatherwood Roof In- 
sulation is the only insulating board fabricated from hardwood. 
The strong hardwood fibers from which it is produced assure 
a board of unusual strength, and one that is light and easy to 
handle. The tough fibrous structure is such that the board is 
not brittle, having a high tensile strength. It is easily cut 
and can be adapted to all types of openings, or roof angles. 
It is uniform in thickness — assured by inspection and approval 
of each board before packing at the mill. Bundles are sub- 
stantial and easy to handle on the job. 

(L4g) Adapts Itself to Irregularities of Roof Decks— 

A prime requirement of an insulating material for application 
over concrete is that it be yielding enough to form itself to the 
irregularities of the deck and, at the same time be rigid enough 
to prevent wrinkling and buckling when embedded in hot pitch 
or asphalt. Weatherwood is midway between the two extremes 
— pliable enough to follow irregularities in the concrete sur- 
face — rigid enough to permit a maximum of economy in han- 
dling and application. The size of Weatherwood Roof Insula- 
tion units practically eliminates any tendency to bridge over 
depressions in the surface of the deck and loss of bonding at 
these points. 

(L4h) Absorbs Expansion and Contraction — An insu- 
lative material must be capable of absorbing expansion and con- 
traction strains within itself without buckling or wrinkling. 

Weatherwood has sufficient rigidity in itself to add con- 
siderable bracing strength to the steel deck and some additional 
resistance to the bending of the steel deck under load. Because 
of the yielding nature of its fibers, it is capable of absorbing a 
large amount of contraction within its own structure. 

(L4i) Low Coefficient of Expansion — A material which 
is to be applied over a roof deck must be of an inert nature, 
that is, it must have a low coefficient of expansion under moisture 
conditions, so that additional expansion and contraction effects 
are not added to the roof deck itself. In addition, a material 
which expands or contracts greatly due to moisture will have a 
tendency to curl as one side or the other becomes moist. This is 
ruinous to any material applied over a roof deck. Because 
of its highly weatherproofed, fibrous structure, there is prac- 
tically no expansion in Weatherwood. Weatherwood is an inert 
or "dead" material, which does not tend to curl or buckle be- 
cause of strain within itself. This characteristic is imparted 
to Weatherwood in the manufacture of the board because of 
its completely homogeneous structure, and the nature of its 
all wood fiber. 


(L5) APPLICATION OVER WOOD DECKS 
SPECIFICATIONS 

Note: Notes are explanatory or advisory only and should 
not be included in the specifications. 

Note: Select and include only those clauses which apply 
to the particular work. Words or clauses in bracketed 
italics are selective — use only when they apply. 


(L5a) Work Included 

Note: Here list and locate definitely the roof areas to be 
covered. If more than one thickness is used, list separately 
and the respective locations or areas covered. 

Note: For data to assist in the selection of the correct 
thicknesses required for fuel and radiation savings and the 
prevention of condensation, see divisions (L9) and (LIO) 
page 21. 


(L5b) Material 

Roof insulation shall be Weatherwood as made by Chicago 
Mill and Lumber Corporation, 111 West Washington Street, 
Chicago. Insulation shall be (specify) thick, (stapled) (lami- 
nated) boards, 2x5 ft. in area. 


( L5c ) Application 

(L5cl) Condition of Deck— Deck shall be dry, finished 
smooth, swept clean and all nails driven flush. 


(L5c2) Felt— Apply (one) (two) layer (s) of dry, satu- 
rated roofing felt over the roof boards. Lap the felt at least 
\V2 in. at joints. (Felt shall extend 6 in. up on walls and all 
vertical surfaces and shall finally be turned over and mopped 
to top of insulation.) 

Note: Felt protects against dripping of pitch or asphalt 
through deck. Include last bracketed italicised clause only 
where there is excessive humidity inside the structure. 
Depending on humidity conditions use one or two layers. 

(L5c3) Laying— Apply the Weatherwood units over the 
felt, bringing the edges to contact. Break joints between alter- 
nate rows. (Where more than one thickness of insulation is 
used on a single area, nail the first layer m place only suffi- 
ciently to maintain its alignment and lay the second layer 
directly over the first, breaking all joints.) 

Note: Include or omit last bracketed italicized clause 
above as required. 

Lay only as much insulation as can be covered and pro- 
tected by the finished roof covering in a single day. Where 
v^ork is stopped, protect the edges of insulation with overlap- 
ping mopped strips of roofing felt, leaving the felt strips as 
a permanent seal. 

(L5c4) Nailing — Insulation shall be secured to deck with 
roofing nails sufficiently long to penetrate through the insula- 
tion and provide firm hold in deck. Space nails approximately 
12 in. apart on centers and not more than 2 in. from edges of 
the unit. Carry one row of nails longitudinally through the 
center of each unit. 

(L5c5) Finished Roofing— Finished roofing shall be 
applied over insulation in accordance with the manufacturer's 
specification, using at least 35 lb. of (pitch) (asphalt) per 
square under the first layers. 


(L6) APPLICATION OVER CONCRETE OR TILE 
ROOF DECKS— SPECIFICATIONS 

Note: Notes are explanatory or advisory only and should 
not be included in the specifications. 

Note: Select and include only those clauses which apply 
to the particular work. Words or clauses in bracketed 
italics are selective — use only when they apply. 


(L6a) Work Included 

Note: Here list and locate definitely the roof areas to be 
covered. If more than one thickness is used, list separately 
and the respective locations or areas covered. 

Note: For data to assist in the selection of the correct 
thicknesses required for fuel and radiation savings and the 
prevention of condensation see divisions (L9) page 16 and 
(LIO) page 21. 


(L6b) Material 

Roof insulation shall be Weatherwood as made by Chi- 
cago Mill and Lumber Corporation, 111 West Washington 
Street, Chicago. Insulation shall be (specify) thick, (stapled) 
(laminated) boards, 2x5 ft. in area. 


(L6c) Application 

(L6cl) Condition of Deck and Insulation— Deck shall 
be smooth, dry and swept clean. Surfaces of Weatherwood 
shall be dry. 

Note: Hot pitch or asphalt will not adhere to moist sur- 
faces. 

(L6c2) Felt— Apply (one) (two) layer (s) of saturated 
roofing felt over the roof deck, thoroughly stuck in hot (pitch) 
(asphalt). Felt shall extend 6 in. up on walls and all vertical 
surfaces .and shall finally be turned over and mopped to top of 
insulation. 

Note: Include this clause where interior of structure is 
subject to high humidity conditions as in paper, textile 
mills, etc., or on applications made during winter months 
where decks do not have opportunity to thoroughly cure 
and dry out before insulation is applied. 


Sweet's 


PAGE IS 


Continued on next page 


B2596 


Chicago Mill and Lumber Corporation 


(L6c3) Priming — Prime deck thoroughly before mopping 
of asphalt. 

Note: Include this clause if insulation is laid in asphalt. 

(L6c4) Laying — Mop deck thoroughly with (composition 
of hot pitch and tar) (hot asphalt) using not less than 35 lb. 
per square. Apply the Weatherwood units while the mopping 
is still hot. Firmly bed the Weatherwood in the binder over 
the entire surface, bringing the edges to contact. Break joints 
between alternate rows. (Where more than one thickness of 
insulation is used on a single area. Mop the surface of the 
first layer and apply the second layer while the binder is still 
hot, breaking all joints. Press second layer firmly into posi- 
tion.) 

Note: Include or omit last bracketed italicized clause 
above as required. 

Lay only as much insulation as can be covered and pro- 
tected by the finished roof covering in a single day. Where 
work is stopped, protect the edges of insulation with over- 
lapping rnopped strips of roofing felt stuck down to the deck. 
Leave strips as a permanent seal when work is resumed. 

(L6c5) Finished Roofing — Finished roofing shall be 
applied over insulation in accordance with the manufacturer's 
specification, using at least 35 lb. of (pitch) (asphalt) per 
square under the first layers. 

(L7) APPLICATION OVER STEEL DECKS 
SPECIFICATIONS 

Note: Notes are explanatory or advisory only and should 
not be included in the specifications. 

Note: Select and include only those clauses which apply 
to the particular work. Words or clauses in bracketed 
italics are selective — use only when they apply. 


(L7a) Work Included 

Note: Here list and locate definitely the roof areas to be 
covered. If more than one thickness is used, list separately 
and the respective locations or areas covered. 

Note: For data to assist in the selection of the correct 
thicknesses required for fuel and radiation savings and the 
prevention of condensation, see divisions (L9) page 16 and 
(LIO) page 21. 


(L7b) Material 

Roof insulation shall be Weatherwood as made by Chi- 
cago Mill and Lumber Corporation, 111 West Washington 
St., Chicago. Insulation shall be (specify) thick, (stapled) 
(laminated) boards, 2 x5 ft. in area. 


(L7c) Application 

(L7c1) Condition of Deck and Insulation — Deck shall be 
smooth, dry and swept clean. Surfaces of Weatherwood shall 
be dry. 

Note: Hot asphalt will not adhere to moist surfaces. 

(L7c2) Laying — Mop deck thoroughly with hot asphalt 
using not less than 35 lb. per square. 

Note: Pitch should not be used over steel decks. 

Apply the Weatherwood units while the mopping is still 
hot. Firmly bed the Weatherwood in the binder over the en- 
tire surface, bringing the edges to contact. Break joints be- 
tween alternate rows. (Where more than one thickness of 
insulation is used on a single area. Mop the surface of the 
first layer and apply the second layer ivhile the binder is still 
hot, breaking all joints. Press second layet firmly into posi- 
tion.) 

Note: Include or omit last bracketed italicized clause 
above as required. 

Lay only as much insulation as can be covered and pro- 
tected by the finished roof covering in a single day. Where 
work is stopped, protect the edges of insulation with over- 
lapping rnopped strips of roofing felt stuck down to the deck. 
Leave strips as a permanent seal when work is resumed. 

(L7c3) Finished Roofing— Finished roofing shall be 
applied over insulation in accordance with the manufacturer's 
specification, using at least 35 lb. of (pitch) (asphalt) per 
square under the first layers. 

(L8) APPLICATION UNDER STEEL DECKS 

Some steel decks are so designed and assembled as to per- 
mit the placing of an insulating board on the under side of 
the deck to act as interior ceiling finish, as well as for insulat- 
ing efficiency and the absorption of sound within the structure. 

This is accomplished by placing the board into the flanges 
of the supporting members of the roof deck, wedging it under 
the stiffening angles. 

The chief requirements of an insulating board for this 
purpose is that it be stiff enough not to sag between supports; 
moisture resistant enough not to require painting or other pro- 
tection ; a comparatively high sound absorption efficiency ; high 
insulating efficiency; a light color with good light reflection 
value, combined with attractive surface appearance. All of the 
requirements are readily met with Weatherwood. 

Application details depend upon the design of each par- 
ticular roof deck. In general, Weatherwood is cut to fit and 
pieces are of a special size. A clearance of one-quarter inch 
is to be left at all edges. End joints should come over fram- 
ing members for scaling purposes. Weatherwood is fastened 
into position by the wedging together of the steel deck. 

Complete specifications adapted to the specific deck con- 
struction will be furnished on application. 


(L9) DETERMINATION OF HEAT RESISTANCE OF INDUSTRIAL ROOFS 


(L9a) General 

One of the chief factors in determining the economic effi- 
ciency of an industrial roof is its resistance to heat flow. This 
heat flow is going on through any roof deck when there is a 
difference in temperature between the interior and exterior 
surfaces of a building. The rate of heat flow depends upon, 
first, the design of the roof structure and second, upon 
the amount of insulation used in combination with the roof 
deck. 

Definite ratings have been established for materials in all 
types of construction which give the rate of heat flow in British 
thermal units of heat per square foot of area for each degree 
of temperature difference and for the thickness of material 
specified in the rating. These B.t.u. ratings must be trans- 
posed into economic units, that is, into the pounds or units of 
fuel wasted by the flow of heat represented in the B.t.u. 
rating. 

The determination of these unit costs is a simple mathe- 
matical computation, but the various factors making up this 
computation must be selected to suit the conditions met in each 
particular problem. The following text, tables and charts illus- 
trate the factors involved, show the method of mathematical 
calculation and by use of the graphical charts, provide a quick 
and easy method of computing the comparative efficiency of any 
roof deck. 


(L9b) Factors Involved 

(L9bl) Conductivity or B.t.u. Ratings — The conduc- 
tivity of the deck, both insulated and uninsulated, must first be 
determined. Tables on page 18 give such B.t.u. ratings for all 
of the common types of roof construction, together with their 
B.t.u. rating insulated in various degrees. In order to obtain 
maximum economic efficiency, the heat loss in units of fuel 
must be determined. The cost of insulating materials is then 
balanced against the savings made possible by their use. 

(L9b2) Area — The square foot area of the roof deck, 
subject to the loss of heat, must be determined. This is fixed 
by the design of the structure. 

(L9b3) Temperature Difference— The average difference 
in temperature must be fixed by comparing the average desired 
inside temperature and the average outside temperature during 
the heating season. This average outside temperature varies 
with locality as shown on the table on page 20, which gives 
these average values for various parts of the United States, 
for the period from October 1 to May 1 or seven months. If 
these values are used, figure a heating season of 210 days. 
Some engineers prefer to figure the actual number of days 
during which the average outside temperature is lower than 
the inside temperature. When this is done, an average outside 
value should be used just covering that period or number of 
days. 


Sweet's 


PAGE 16 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2597 


(L9b4) Fuel — The fuel units consumed by loss of heat 
through a roof naturally depends upon the amount of heat rep- 
resented by each fuel unit. A partial list of fuels showing their 
comparative heat contents follows : 

Anthracite coal 11,600 to 13,500 B.t.u. per lb. 

Bituminous coal 12,000 to 14,500 B.t.u. per lb. 

Distillate oil— 32° to 40° Baume. 135,000 to 140,000 B.t.u. per gal. 

Natural gas 1,131 B.t.u. per cu. ft. 

Coal Gas 560 B.t.u. per cu. ft. 

(L9b5) Efficiency of Heating Equipment — The efficiency 
of the fuel burning equipment determines the percentage of the 
actual heat content of the fuel that is turned into useful heat 
in the structure. Coal burning equipment will usually range 
between 50% efficient for residential buildings up to 65% effi- 
cient for industrial plants. Oil burning equipment will range 
between 65% and 75% under like conditions. Gas efficiency is 
usually figured at about 80%. 

(L9c) MATHEMATICAL COMPUTATION FOR 
FUEL SAVING 

In computing mathematically the fuel loss through any 
roof the procedure is as follows : the conductivity or B.t.u. 
rating is multiplied by the area of the roof in square feet, by 
the difference in average inside and outside temperatures dur- 
ing the heating season, by the number of days in the heating 
season (period covered by average outside temperature value) 
and finally, by 24 hours to change the B.t.u. hourly rating into 
day units. The product of this series of multiplications is then 
divided by the heat contents per unit of the fuel used and by 
the efficiency of the fuel burning equipment. In the case of 
coal, to reduce the pounds of fuel to tons, the product is di- 
vided by 2000. 

A typical determination of coal saving by the use of one 
inch of Weatherwood follows : 
Location : Chicago, Illinois. 

Roof deck — 5-in. concrete slab covered with built up roofing. 

Conductivity uninsulated (from table on page 18) 532 

Conductivity with 1-in. Weatherwood (from table on 

page 18 203 

Area of roof deck (assumed) 20,000 sq. ft. 

Inside temperature (average throughout 24 hrs.) 60° F. 

Exterior temperature (average for seven months from 

table on page 19 36.4° F. 

Temperature difference 23.6° F. 

Heating season (seven months used for temperature). .210 days 

Fuel (coal assumed at) 12,000 B.t.u. per lb. 

Boiler efficiency (assumed) 65% 

(.532 — .203) X 20,000 X 23.6 X 210 X 24 

■ 50.2 tons 

12,000 X .65 X 2000 

(L9d) RADIATION REQUIREMENTS 

' (L9dl) General — The amount of radiation saved by the 
insulation of the roof also enters into the determination of 
economic efficiency of the roof structure. The factors involved 
in mathematically computing the radiation saving by insulation 
are as follows : 

L9d2) Conductivity— The conductivity or B.t.u. rating 
must be determined for the deck, both uninsulated and with the 
amount of insulation added which is to be considered, as in 
the case with computations for coal saving. 

(L9d3) Temperatures — Interior temperature average dur- 
ing the day and night is not used as in the case of coal saving, 
but the maximum required temperature dirring any extended 
period is the temperature used. Determine the lowest outside 
temperature from table on page 19 and to this add 15°, as it 
is only necessary that sufficient radiation be provided to furnish 
a maximum temperature with an outside temperature of approx- 
imately 15° above the lowest. This is because the lowest out- 
side temperature is very unusual and probably exists for only 
short periods. 

(L9d4) Type of Radiation— The type of radiation, that 
is, steam, vapor or hot water, will determine the B.t.u. rating 
per square foot for the radiation used. Usual values for these 
three types of radiation are as follows : 

Steam radiation 240 B.t.u. per sq. ft. 

Vapor system 200 B.t.u. per sq. ft. 

Hot water system 150 B.t.u. per sq. ft. 


(L9e) MATHEMATICAL COMPUTATION FOR 
RADIATION SAVINGS 

The difference in temperature between maximum interior 
temperature desired and a temperature 15° above the lowest 
recorded outside temperature, should be multiplied by the dif- 
ference in conductivity of the insulated roof as compared to 
the uninsulated roof and multiplied again by the roof area. 
Divide the product of this multiplication by the B.t.u. rating of 
the type of radiation to be used. A typical illustration of radia- 
tion savings by the use of Weatherwood as in the previous 
problem follows: 

Example 

Outside low temperature (lowest recorded plus 15°) from 

table on page 19 -8° F. 

Inside maximum desired temperature 65° F. 

Temperature difference 73° F. 

Type of radiation (steam assumed) 240 B.t.u. per sq. ft. 

Take other conditions from analysis of fuel saving (L9c) 
73° X (.532 — .203) X 20,000 

= 2001 sq. ft. of radiation saved. 

240 

(L9f) GRAPHIC SOLUTION OF FUEL AND 
RADIATION SAVINGS 

(L9fl) General — Easy and rapid calculation of the sav- 
ings in coal and radiation on any type of deck and with any 
amount of insulation may be found without the necessity of 
mathematically computing such savings by the use of graphic 
chart on page 20. In using this chart, first determine the 
factors which influence the solution, just as in the mathemati- 
cal computations given in (L9c) and (L9e). 

(L9f2) Fuel Saving Computation — Having determined 
these factors turn to the chart and select the pomt on the con- 
ductivity scale representing the conductivity of the uninsulated 
roof deck as determined from tables on page 18 or calculated. 
The scale of conductivities is found on the left side of the ver- 
tical center line at the top of the chart and ranges from .0 to 
.9 B.t.u. per hour. From this point pass horizontally to the 
left to an intersection with the line representing the thickness 
of Weatherwood to be used. From this intersection pass ver- 
tically down to the diagonal line representing the proper tem- 
perature difference (average inside and average outside) on 
the lower half of the chart. From this intersection pass hori- 
zontally to the right to ^ intersection with the diagonal line 
representing number of days in heating season. P>om this 
intersection pass vertically up to an intersection with the line 
representing the fuel to be used and efficiency of plant. From 
this intersection pass horizontally to the right to the scale at 
the right edge of the chart. The readings on this scale give 
the units of fuel saved over one heating season per thousand 
square feet of roof area as follows : 

Scale reading direct = tons of coal 
Scale reading X 100 = gallons of oil 
Scale reading X 10,000 = cu. ft. of gas 

In order to determine the total fuel required per thousand 
square feet of roof area for any deck either insulated or unin- 
sulated, follow exactly the same procedure but start with the 
proper conductivity on the horizontal ^cale at the center of the 
left hand portion of the chart on page 20 and do not use the 
upper half of that portion of the chart or the Weatherwood 
curves. 

(L9f3) Radiation Savings— In order to determine the 
savmgs, start again at the point on the conductivity scale rep- 
resenting conductivity of uninsulated deck and pass horizontally 
across to the line representing the thickness of Weatherwood. 
From this intersection, pass vertically down to the diagonal line 
representing temperature difference between maximum inside 
and low outside temperatures. From this intersection, pass 
horizontally to the right to an intersection with one of the 
three radiation scales at the right edge, either steam, vapor, or 
hot water. The reading thus established on this scale is the 
number of square feet saved by use of the insulation for each 
1000 sq. ft. of roof. 

To determine the total required radiation for any deck, 
start at the horizontal scale at the center of the page with the 
conductivity of the deck as it is to be built and by intersecting 
the temperature difference line and the radiation scale, the 
reading on this last scale gives the total square feet of radia- 
tion required for each 1000 sq. ft. of this roof deck. 


Sweet's 


PAGE 17 


Continued on next page 


B2598 


Chicago Mill and Lumber Corporation 


COEFFICIENTS OF TRANSMISSION (U) 

Vorinii<5 T^vnp<s of Klaf Roof Oecks dovered with "Built-ur) Roofincr 

Note: These coefficients are expressed in B.t.u. per hour per square foot per 1 degree Fahrenheit difference in 
temperature between the air on the two sides and are based on an outside wind exposure of 15 miles per hour. 

Note: These tables are reproduced from The American Society of Heating and Ventilating Engineers Guide, by special permission. 


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0.221 


O.lOl 


0.324 


2Z8 


r»ber In^alat^or? 
((board form) 


0.208 


0.206 


O.ZOl 


0.l9fo 


0.192 


0.188 


0.185 


0.169 


0.160 


0.138 


0.121 


0.165 


0.154 


0.217 


22^ 


r 


0.158 


0.157 


0.154 


0.152 


0.149 


0.146 


0.145 


0.133 


0.129 


0.114 


0.102 


0.132 


0.1Z5 


0.163 


230 


l'/2 


ai28 


0.127 


0.125 


0123 


O.lZl 


0.119 


au9 


O.lll 


o.loe 


0.0^ 


0.089 


O.IIO 


0.105 


0.131 


231 


V 


0.107 


O.IO() 


0.105 


0.104 


0.102 


0.101 


O.IOI 


ao96 


0.095 


0.085 


a 078 


0.095 


0.091 


0.109 


232 


r 


Cork, boord 


0.151 


0.150 


0.147 


0.14 S 


0.142 


0.140 


0.138 


0.129 


0.124 


0.110 


0.100 


0.127 


0.120 


0.155 


233 


Vfi 


0.121 


0.120 


0.118 


O.llib 


0.115 


0.113 


0.112 


O.lOfe 


0.103 


0.093 


0085 


0.105 


0.104 


0.123 


234 


r 


0.100 


O.lOO 


O.m 


0.098 


0.096 


0.095 


0095 


0.090 


a 088 


0.081 


0.075 


0.089 


0.086 


0.102 


235 


So/t fdt or Quilt 
(Mot Com pre -^^cd) 


0.1^4 


o.m 


0.188 


0.184 


ai8o 


0.176 


0.174 


0.160 


0.152 


0.132 


0.116 


0.157 


0.147 


0.202 


236 


r 


0.143 


0.142 


0.139 


0.137 


0.135 


0.133 


0.132 


0.123 


0.118 


0.106 


0096 


0.121 


0.115 


0.147 


237 


r 


Cellular C^p^i^m 


0.170 


ai65 


O.lbl 


0.159 


Q156 


ai54 


0.143 


0.136 


0.120 


0.107 


*Precast cement. fNominal thicknesses specified — actual thicknesses used in computations. 

tThe figures in this table may be used with sufficient accuracy for wood lath and plaster ceilings. 


TLAT IZOOfS - kJO PLASTLd CClUViCIS (UKiOteSlDE Of BOOf DfCC UKiflKil^UEDj 


The values' U m Ihi-i Table arc ba^ on the 
jt)llowinq Internal Condudivitie^ (C) vfhich are 
en. pressed 10 &.tu. per Ur. per per I'f 
Zoofmq \M'i per 1* 
Concrete 8.30 per 1' 
Cv^p^um (15 fiber) Z.30 perl' 
Wood CY«Ilow Pine or f.r) l.oo per \[ 
fiberln5dlat»on(6oaTd/br»«) 0.35 perl' 
felts 4 Qutlb? CVt) 0-Z7 perl* 
Cor t board O.V) per 1' 
Plo-kter R>oord 3.04 per [' 
Cellular Gvp5utn (if) 0.77 per 1' 


Concrete ^oof'^ 
• 

^ In^ulattow-^ 


Wood 

\ In^ulakton^ 


Poured Q^^'^Kxrry. 
Containmq 15% 
Wood fiber 

\ Vnsulobonr 


flat Uela\ 
Q.oof'y 

\ In^ulatiortr 


Corrugated 
Iron Coo/'s 


X 


. , . # . V * ■ . . • 


Uetoi / 

/ 


Concrete 


I v/ood-y 


Tbickness - X 


TVnctne-v-i - X t 


Thtctncss - X 


eoo/= 

Vio. 


Thickness of 
ln9ulot»on 


In^ulatton 


lVe*« 


V 


3* 


4* 


y 


<b* 


r 


2* 


y 


4' 


3" 


4* 


a 


b 


c 


di 


c 


/ 


q 


h 


I 


1 


m 


n 


0 


216 


0* 


Kio ln'^u\atlor7 


0.(,8C 


0.(,58 


0.<jlO 


0.568 


0.532 


0.500 


0.485 


0386 


0.345 


0.Z56 


0.204 


0.36S 


0.318 


0.781 


1.50 t 


■ 217 


'/^ 


fiber ln'^alah10^ 


0.334 


0.330 


0.317 


0.306 


0.295 


0.285 


0.280 


0.243 


0276 


0.184 


0.156 


0.237 


0.214 


0.358 


218 


I' 


• (bcx>rdl form) 


0.222 


0.Z20 


0.214 


0.20S 


0.203 


0.199 


o.\% 


0.178 


0.168 


0.144 


0.126 


0.174 


0.162 


0.232 


21*1 


O.IG(, 


0.1^,5 


O.IGZ 


0.15^ 


0.156 


0.153 


O.ISI 


0.140 


0.134 


0.118 


0.106 


0.138 


0.130 


0.172 


220 


1' 


0.133 


0.132 


0.130 


0.118 


0.\2(c 


0.124 


0.123 


O.llG 


0.117 


0.100 


0.091 


0.114 


0.109 


0.136 


221 


r 


CorlL board 


0.208 


0.206 


0.201 


0.H6 


0.192 


0.188 


0.165 


0.169 


0.160 


0.138 


0.121 


0.165 


0.154 


0.217 


222 


0.154 


0.153 


0.151 


0.148 


0.145 


0.143 


0.142 


0.132 


0.126 


0.124 


0.101 


0.130 


0.120 


0.160 


223 


2' 


0.123 


O.IZI 


0.120 


0.119 


o.in 


0.115 


0.114 


0.108 


0104 


0.095 


a086 


0.107 


0.101 


0.126 


224 


Sc^fc rdt or Quilt 


0.301 


0.2S7 


O.Wo 


0.277 


a268 


0.260 


0.256 


0-225 


0.210 


0.174 


0.148 


0 2n 


0.200 


o.sn 


22s 


r 


(KJot Compressed) 


0.R3 


O.ISI 


0.187 


0.18^ 


0.119 


0.175 


0.174 


0.159 


0.151 


O.l^l 


0.116 


0.156 


0.146 


0.201 


2l(o 


2" 


Cciluilar (^yp^um 


0.246 


0,243 


0.2% 


a22S 


0.223 


0.217 


0.214 


0.193 


0.182 


0.154 


0.133 


*Precast c 
JNo built-i 


ement. fNominal thicknesses specified — actual thicknesses used in computations. 

ip roofing. The value for corrugated iron is obtained by assuming that the surface area is increased 50 per cent. 


These tables are based on the use of V2-in. insulating board with rated efficiency of .33 B.t.u. per in. thickness per sq. ft. 
per hour. The thermal conductivity of Weatherwood is .32 B.t.u., therefore the use of Weatherwood increases these wall 
efficiencies slightly over the figures given above. 


Sweet's 


PAGE 18 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2599 


CLIMATIC CONDITIONS 
COMPILED FROM U. S. WEATHER BUREAU RECORDS 


Col. A 


State 


Ala. . 

Ariz. . 

Ark.. 

Cal . . 

Colo. 

Conn. . 
D.C.. 
Fla. . . 
Ga... 

Idaho . 

111. . . . 

Ind. . . 

Iowa. . 

Kans . . 

Ky... 
La.. . . 

Me. . . 

Md. . . 
Mass. . 
Mich . . 

Minn.. 

Miss. . 
Mo. . . 

Mont.. 
Nebr.. 


Col. B 


City 


Mobile 

Birmingham . . . 

Phoenix 

Flagstaff 

Fort Smith . . . . 

Little Rock 

San Francisco . . 

Los Angeles. . . . 

Denver 

Grand Junction 

New Haven 

Washington .... 

Jacksonville. . . 

Atlanta 

Savannah 

Lewiston 

Pocatello 

Chicago 

Springfield 

Indianapolis. . . 

Evansville 

Dubuque 

Sioux City 

Concordia 

Dodge City 

Louisville 

New Orleans. . . 

Shreveport 

East port 

Portland 

Baltimore 

Boston 

Alpena 

Detroit 

Marquette 

Duluth 

Minneapolis. . . . 

Vicksburg 

St. Joseph 

St. Louis 

Springfield 

Billings 

Havre 

Lincoln 

North Platte. . . . 


Col. C 


Col. D 


Col. E 


Col. F 


Col. A 


Average 


Direction 


Average 


Lowest 


wind ve- 


temp., 


locity Dec. 


of prevail- 


State 


Oct. 1st- 


tempera- 


Jan., Feb. 


ing wind, 


May 1st 


ture 


miles per 
hr. 


Dec, Jan. 
Feb. 


57.7 


-1 


8.3 


N 


Nev. . . . 


53.9 


-10 


8.6 


N 


59.5 


16 


3.9 


E 


N.H... 


34.9 


-25 


6.7 


SW 


N.J . . . . 


49.5 


-15 


8.0 


E 


N.Y.. 


51.6 


-12 


9.9 


NW 


54.3 


29 


N 


58.6 


28 


NE 


N.M. . 


39.3 


-29 


7.4 


s 


N.C.. . . 


39.2 


-16 


5.6 


SE 


38.0 


-14 


9 3 


N 


N.D. . . 


43.2 


-15 


7.3 


NW 


61.9 


10 


8.2 


NE 


Ohio . . . 


51.4 


- 8 


11.8 


NW 


58.4 


8 


8.3 


NW 


Okla . . . 


42.5 


-13 


4.7 


E 


Ore 


36.4 


-20 


9 3 


SE 


36.4 


-23 


17.0 


SW 


Pa 


39.9 


-24 


10.2 


NW 


40.2 


-25 


11.8 


s 


R.I 


44.1 


-15 


8.4 


s 


S.C 


33.9 


-32 


6.1 


NW 


32.1 


-35 


12.2 


NW 


S. D.... 


38.9 


-25 


7.3 


N 


40.2 


-26 


10.4 


NW 


Tenn . . . 


45.2 


-20 


9.3 


SW 


61.5 


7 


9 6 


N 


Texas. . 


56.2 


-5 


7.7 


SE 


31.1 


-23 


13.8 


W 


33.6 


-17 


10 1 


NW 


Utah. . . 


43.6 


-7 


7 2 


NW 


37.6 


-13 


11.7 


W 


Vt 


29.1 


-27 


11.3 


w 


Va 


35.4 


-24 


13. 1 


SW 


27.6 


-27 


11.4 


NW 


25.1 


-41 


11.1 


SW 


Wash... 


29.6 


-33 


11.5 


NW 


56.0 


-1 


7.6 


SE 


W.Va. . 


40.3 


-24 


9.1 


NW 


43.3 


-22 


11.8 


NW 


Wis... 


43.0 


-29 


11.3 


SE 


34.7 


-49 


W 


27.7 


-57 


"8.'7 


SW 


Wyo . . . 


37.0 


-29 


10.9 


N 


34.6 


-35 


9.0 


W 


Col. B 


City 


Tonopah 

Winnemucca. . . 
Concord 

Atlantic City. . 

Albany 

Buffalo 

New York 

Santa Fe 

Raleigh 

Wilmington . . . . 

Bismarck 

Devil's Lake. . . 

Cleveland 

Columbus 

Oklahoma City. 

Baker 

Portland 

Philadelphia . . . 

Pittsburgh 

Providence .... 

Charleston 

Columbia 

Huron 

Rapid City .... 

Knoxville 

Memphis 

El Paso 

Fort Worth .... 

San Antonio . . . 

Modena 

Salt Lake City. 

Burlington 

Norfolk 

Lynchburg 

Richmond 

Seattle 

Spokane 

Elkins 

Parkersburg . . . . 

Green Bay 

La Crosse 

Milwaukee 

Sheridan 

Lander 


Col. C 


Average 
temp., 
Oct. 1st- 
May 1st 


Col. D 


39.6 

37.9 

33.4 

41.6 

35.1 

34.7 

40.3 

38.0 

49.7 

53.1 

24.5 

18.9 

36.9 

39.9 

48.0 

34.1 

45.9 

41.9 

40.8 

37.6 

56.9 

53.7 

28.1 

32.3 

47.0 

50.9 

53.0 

54.7 

60.7 

38.1 

40.0 

29.3 

49.1 

45.2 

47.4 

45.3 

37.5 

38.8 

41.9 

28.6 

31.2 

33.0 

31.0 

28.9 


Lowest 
tempera- 
ture 


-7 
-28 
-35 

-7 
-24 
-14 

-6 
-13 

-2 
5 

-45 
-44 
-17 
-20 
-17 
-20 
-2 
-6 
-20 
-9 
7 

-2 
-43 
-34 
-16 
-9 
-2 
-8 
4 

-24 
-20 
-27 
2 

-7 
-3 
3 

-30 
-21 
-27 
-36 
-43 
-25 
-45 
-36 


Col. E 


Average 
wind ve- 
locity Dec, 
Jan., Feb. 
miles per 
hr. 


9.9 
9.5 
6.0 
10.6 
7.9 
17.7 
13.3 
7.3 
7.3 
8.9 

il.'i 
14.5 
9.3 
12.0 
6.0 
6.5 
11.0 
13.7 
14.6 
11.0 
8.0 
11.5 
7.5 
6.5 
9.6 
10.5 
11.0 
8.2 
8.9 
4.9 
12.9 
9.0 
5.2 
7.4 
9.1^ 

'4.*8 
6.6 

12.8 
5.6 

11.7 
5.3 
3.0 


Col. F 


Direction 
of prevail- 
ing wind, 
Dec, Jan., 
Feb. 


SE 
NE 

NW 
NW 
S 

w 

NW 

NE 

SW 

SW 

NW 

W 

SW 

SW 

N 

SE 

S 

NW 

NW 

NW 

N 

NE 

NW 

W 

SW 

NW 

NW 

NW 

N 

W 

SE 

S 

N 

NW 
S 

SE 
SW 
W 

s 

SW 
NW 

w 

NW 
NE 


INSIDE TEMPERATURES USUALLY SPECIFIED 


Type of building 

Schools — 

Class rooms 

Assembly rooms 

Gymnasiums 

Toilets and baths 

Wardrobe and locker rooms. . . . 

Kitchens 

Dining and lunch rooms 

Playrooms 

Natatoriums 

Theatres — 

Seating space 

Lounge rooms 

Toilets 

Hotels — 

Bedrooms and baths 

Dining rooms 

Kitchens and laundries 

Ball rooms 

Toilets and service rooms 


Deg. Fahr. 


Type of building 

Hospitals — 

Private rooms 

Private rooms (surgical) 

Operating rooms 

Wards 

Kitchens and laundries 

Toilets 

Bathrooms 

Homes — 

Where 68° is generally the desirable standard of tem 
perature a guarantee of 70° is customarily exacted. 

Stores 

Public buildings 

Warm air baths 

Steam baths 

Factories and machine shops 

Foundries and boiler shops 

Paint shops 


68 
66-68 
55-65 

70 
65-68 

66 
65-68 
60-65 

75 


68-72 
68 
68 

70 
70 
66 
65-68 
68 


Sweet's 


PAGE 19 


Continued on next payc 


B2600 


Chicago Mill and Lumber Corporation 


CHART FOR GRAPHIC SOLUTION OF FUEL AND RADIATION PROBLEMS 


RELATIVE HUMIDITY— Degrees Wet-bulb Depressions— Fahrenheit 


Dry-Bulb 


1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 


13 


14 


15 


16 


Temp. F. 

50 

52 


93. 


.87. 


.80. 


.74. 


.67. 


.61. 


.55. 


.49. 


.43. 


.38. 


.32. 


.27. 


.21. 


.16. 


.10. 


. .5 


94. 


.87. 


.81. 


.75. 


.69. 


.63. 


.57. 


.51. 


.46. 


.40. 


.35. 


.29. 


.24. 


. 19. 


. 14. 


. .9. 


54 


94. 


.88. 


.82. 


.76. 


.70. 


.64. 


.59. 


.53. 


.48. 


.42. 


.37. 


.32. 


.27. 


.22. 


.17. 


.12. 


56 

58 

59 

60 

61 

62 

63 

64 

65 

66 

67 


94. 


.88. 


.82. 


.76. 


.71. 


.65. 


.60. 


.55. 


.50. 


.44. 


.39. 


.34. 


.30. 


.25. 


.20. 


.16. 


94. 


.88. 


.83. 


.77. 


.72. 


.66. 


.61. 


.56. 


.51. 


.46. 


.41. 


.37. 


.32. 


.27. 


.23. 


.18. 


94. 


.89. 


.83. 


.78. 


.72. 


.67. 


.62. 


.57. 


.52. 


.47. 


.42. 


.38. 


.33. 


.29. 


.24. 


.20. 


94. 


.89. 


.83. 


.78. 


.73. 


.68. 


.63. 


.58. 


.53. 


.48. 


.43. 


.39. 


.34. 


.30. 


.26. 


.21. 


94. 


.89. 


.84. 


.78. 


.73. 


.68. 


.63. 


.58. 


.53. 


.49. 


.44. 


.40. 


.35. 


.31. 


.27. 


.22. 


94. 


.89. 


.84. 


.79. 


.74. 


.69. 


.64. 


.59. 


.54. 


.50. 


.45. 


.41 . 


.36. 


.32. 


.28. 


.24. 


95. 


.89. 


.84. 


.79. 


.74. 


.69. 


.64. 


.60. 


.55. 


.51. 


.46. 


.42. 


.37. 


.33. 


.29. 


.25. 


95. 


.90. 


.84. 


.79. 


.75. 


.70. 


.65. 


.60. 


.56. 


.51. 


.47. 


.43. 


.38. 


.34. 


.30. 


.26. 


95. 


.90. 


.85. 


.80. 


.75. 


.70. 


.66. 


.61 . 


.57. 


.52. 


.48. 


.44. 


.39. 


.35. 


.31. 


.27. 


95. 


.90. 


.85. 


.80. 


.75. 


.71. 


.66. 


.61 . 


.57. 


.53. 


.48. 


.44. 


.40. 


.36. 


.32. 


.29. 


95 . 


.90. 


.85. 


.80. 


.76. 


.71. 


.66. 


.62. 


.58. 


.53. 


.49. 


.45. 


.41. 


.37. 


.33. 


.^0. 


68 

69 

70 

71 

72 

73 

74 

75 

76 

77 

78 

79 

80 

81 

82 

83 

84 

85 

86 

87 

88 

89 

90 

92 

94 

96 

98 


95. 


.90. 


.85. 


.80. 


.76. 


.71. 


.67. 


.62. 


.58. 


.54. 


.50. 


.46. 


.42. 


.38. 


.34. 


.31. 


95. 


.90. 


.85. 


.81. 


.77. 


.72. 


.67. 


.63. 


.59. 


.55. 


.51. 


.47. 


.43. 


.39. 


.35. 


.32. 


95. 


.90. 


.86. 


.81. 


.77. 


.72. 


.68. 


.64. 


.59. 


.55. 


.51. 


.48. 


.44. 


.40. 


.36. 


.33. 


95. 


.90. 


.86. 


.81. 


.77. 


.72. 


.68. 


.64. 


.60. 


.56. 


.52. 


.48. 


.45. 


.41. 


.37. 


.33. 


95. 


.91. 


.86. 


.82. 


.77. 


.73. 


.69. 


.65. 


.61. 


.57. 


.53. 


.49. 


.45. 


.42. 


.38. 


.34. 


95. 


.91. 


.86. 


.82. 


.78. 


.73. 


.69. 


.65. 


.61. 


.57. 


.53. 


.50. 


.46. 


.42. 


.39. 


.35. 


95. 


.91. 


.86. 


.82. 


.78. 


.74. 


.69. 


.65. 


.61. 


.58. 


.54. 


.50. 


.47. 


.43. 


.39. 


.36. 


96. 


.91. 


.86. 


.82. 


.78. 


.74. 


.70. 


.66. 


.62. 


.58. 


.54. 


.51. 


.47. 


.44. 


.40. 


.37. 


96. 


.91. 


.87. 


.82. 


.78. 


.74. 


.70. 


.66. 


.62. 


.59. 


.55. 


.51. 


.48. 


.44. 


.41 . 


.38. 


96. 


.91. 


.87. 


.83. 


.79. 


.74. 


.71. 


.67. 


.63. 


.59. 


.56. 


.52. 


.48. 


.45. 


.42. 


.39. 


96. 


.91. 


.87. 


.83. 


.79. 


.75. 


.71. 


.67. 


.63. 


.60. 


.56. 


.53. 


.49. 


.46. 


.43. 


.39. 


96. 


.91. 


.87. 


.83. 


.79. 


.75. 


.71. 


.68. 


.64. 


.60. 


.57. 


.53. 


.50. 


.46. 


.43. 


.40. 


96. 


.91. 


.87. 


.83. 


.79. 


.75. 


.72. 


.68. 


.64. 


.61. 


.57. 


.54. 


.50. 


.47. 


.44. 


.41 . 


96. 


.92. 


.88. 


.84. 


.80. 


.76. 


.72. 


.69. 


.65. 


.61 . 


.58. 


.55. 


.51. 


.48. 


.45. 


.42. 


96. 


.92. 


.88. 
.88. 


.84. 


.80. 


.76. 


.72. 


.69. 


.65. 


.61. 


.58. 


.55. 


.51. 


.48. 


.45. 


.42. 


96. 


.92. 


.84. 


.80. 


.76. 


.73. 


.69. 


.66. 


.62. 


.59. 


.56. 


.52. 


.49. 


.46. 


.43. 


96. 


.92. 


.88. 


.84. 


.80. 


.76. 


.73. 


.69. 


.66. 


.62. 


.59. 


.56. 


.52. 


.49. 


.46. 


.43. 


96. 


.92. 


.88. 


.84. 


.81. 


.77. 


.73. 


.70. 


.66. 


.63. 


.60. 


.57. 


.53. 


.50. 


.47. 


.44. 


96. 


.92. 


.88. 


.84. 


.81. 


.77. 


.73. 


.70. 


.66. 


.63. 


.60. 


.57. 


.53. 


.50. 


.47. 


.44. 


96. 


.92. 


.88. 


.85. 


.81. 


.77. 


.74. 


.70. 


.67. 


.64. 


.61. 


.57. 


.54. 


.51. 


.48. 


.46. 


96. 


.92. 


.88. 


.85. 


.81. 


.77. 


.74. 


.70. 


.67. 


.64. 


.61. 


.57. 


.54. 


.51 . 


.48. 


46. 


96. 


.92. 


.88. 


.85. 


.81. 


.78. 


.74. 


.71. 


.68. 


.65. 


.61. 


.58. 


.55. 


.52. 


.49. 


.47. 


96. 


.92. 


.89. 


.85. 


.81. 


.78. 


.74. 


.71. 


.68. 


.65. 


.61. 


.58. 


.55. 


.52. 


.49. 


47. 


96. 


.92. 


.89. 


.85. 


.82. 


.78. 


.75. 


.72. 


.68. 


.65. 


.62. 


.59. 


.56. 


.53. 


.50. 


48. 


96. 


.93. 


.89. 


.85. 


.82. 


.79. 


.75. 


.72. 


.69 


.66. 


.63. 


.60. 


.57. 


.54. 


.51. 


.49. 


96. 


.93. 


.8Q. 


.86. 


.82. 


.79. 


.76. 


.73. 


.69. 


.66. 


.63. 


.61. 


.58. 


.55. 


.52. 


.50. 


96. 


.93. 


.89. 


.86. 


.83. 


.79. 


.76. 


.73. 


.70. 


.67. 


.64. 


.61. 


.58. 


.56. 


.53. 


.50. 


100 

104 

108 

112 

116 

120 


96. 


.93. 


.89. 


.86. 


.83. 


.80. 


.77. 


.73. 


.70. 


.68. 


.65. 


.62. 


..S9. 


.56. 


.54. 


.51. 


97. 


.93. 


.90. 


.87. 


.83. 


.80. 


.77. 


.74. 


.71 . 


.69. 


.66. 


.63. 


.60. 


.58. 


.55. 


.53. 


97. 


.93. 


.90. 


.87. 


.84. 


.81. 


.78. 


.75. 


.72. 


.70. 


.67. 


.64. 


.62. 


.59. 


.57. 


.54. 


97. 


.94. 


.90. 


.87. 


.84. 


.81. 


.79. 


.76. 


.73. 


.70. 


.68. 


.65. 


.63. 


.60. 


.58. 


. 55 . 


97. 


.94. 


.91. 


.88. 


.85. 


.82. 


.79. 


.76. 


.74. 


.71. 


.69. 


.66. 


.64 


.61. 


.59. 


.57. 


97. 


.94. 


.91. 


.88. 


.85. 


.82. 


.80. 


.77. 


.74. 


.72. 


.69. 


.67. 


.65. 


.62. 


.60. 


.58. 


Sweet's 


PAGE 20 


17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 


. .4 

. .8. 

.11. 

.14. 

.16. 

.17. 

.18. 

.20. 

.21. 

.22. 

.24. 

.25. 

.26. 

.27. 

.28. 

.29. 

.30. 

.31. 

.32. 

.33. 

,34. 

.34. , 

,35. . 

36. . 

37. . 

38. . 

39. . 

39. . 

40. . 

40. . 

41. . 

42. . 

43. . 

43. . 

44. . 

44. . 

45. . 

46. . 

47. . 

48. . 

49. . 

50. . 

52. . 

53 . . 
, 54 . . 
.55. 


.3 
.7 
10 
11 
13 
14 
16 
17 
18 
20 

91 

22 
23 
24 
25 
27 
28 
29 

29. . 

30. . 
31 . . 

32. . 

33. . 

34. . 

35. . 

36. . 

36. . 

37. . 

37. . 

38. . 

39. . 

40. . 

40. . 
41 . . 

41 . . 

42. . 

43. . 

44. . 

45. . 

46. . 

48. . 

49. . 

51. . 

52. . 

53 . . 


Note: Figures horizontally opposite 
the dry-bulb reading and vertically oppo- 
site the twet-bulb reading give the per- 
centage of relative humidity. 


23.. 20. 


.17. 


.14. 


.11 


24. 


.21. 


.18. 


. 15. 


.12. 


. .9. 


. .7. 


. .4. 


. .1 


25. 


.22. 


. 19. 


. 16. 


. 13. 


.11. 


. .8. 


. .5. 


. .3 


26. 


.23. 


.20. 


.17. 


. 14. 


. 12. 


. .9. 


. .6. 


. .4 


27. 


.24. 


.21. 


. 18. 


. 16. 


.13. 


. 10. 


. .8. 


. .5. 


. .3 


28. 


.25. 


.22. 


. 19. 


.17. 


. 14. 


. 11 . 


. .9. 


. .6. 


. .4. 


..1 


29. 


.26. 


.23. 


.20. 


. 18. 


. 15. 


. 12. 


.10. 


. .7. 


. .5. 


. .3 


30. 


.27. 


.24. 


.21 . 


. 19. 


. 16. 


. 13. 


.11. 


. .9. 


. .6. 


. .4 


30. .28. 


.25. 


.22. 


.20. 


. 17. 


. 14. 


.12. 


. 10. 


. .7. 


. .5 


31 . 


.29. 


.26. 


.23. 


.21. 


. 18. 


.15. 


. 13. 


.11. 


. .8. 


. .6. 


, .3. 


.2 


32. 


.29. 


.26. 


.24. 


.21. 


. 19. 


. 16. 


.14. 


. 12. 


. .9. 


. .7. 


. .5. 


.3 


33. 


.30. 


.27. 


.25. 


.22. 


.20. 


.17. 


.15. 


. 13. 


. 10. 


. .8. 


. .6. 


. .4 


33. 


.31. 


.28. 


.26. 


.23. 


.21. 


. 18. 


. 16. 


. 14. 


.11. 


. .9. 


. .7. 


. .5 


34. 


.32. 


.29. 


.26. 


.24. 


.22. 


. 19. 


. 17. 


.15. 


. 12. 


. 10. 


. .8. 


. . 6 


35. 


.32. 


.30. 


.27. 


.25. 


.22. 


.20. 


. 18. 


. 15. 


. 13. 


.11. 


. .9. 


. .7 


36. 


.33. 


.31. 


.28. 


.26. 


.23. 


.21 . 


. 19. 


. 16. 


. 14. 


. 12. 


. 10. 


. .8 


36. 


.34. 


.31. 


.29. 


.26. 


.24. 


.22. 


. 19. 


.17. 


. 15. 


. 13. 


.11. 


. .9 


37. 


.35. 


.32. 


.30. 


.28. 


.25. 


23. 


.21 . 


. 19. 


. 17 . 


. 15. 


. 13. 


.11 


38. 


.36. 


.33. 


.31 . 


.29. 


.27. 


.24. 


.22. 


.20. 


. 18. 


. 16. 


. 14. 


. 12 


39. 


.37. 


.35. 


.32. 


..30. 


.28. 


.26. 


.24. 


.22. 


.20. 


. 18. 


. 16. 


. 14 


40. 


.38. 


.36. 


.34. 


.32. 


.29. 


.27. 


.25. 


.23. 


.21 . 


. 19. 


.17. 


.15 


41. 


.39. 


.37. 


.35. 


.33. 


.30. 


.28. 


.26. 


.24. 


.22. 


.21 . 


. 19. 


. 17 


43. 


.41. 


.39. 


.37. 


.35. 


.33. 


.31. 


.29. 


.27. 


.25. 


.23. 


.21. 


.20 


45. 


.43. 


.41. 


.39. 


.37. 


.35. 


. 33 . 


.31. 


.29. 


.27. 


.25. 


.24. 


22 


47. 


.44. 


.42. 


.40. 


.38. 


.36. 


.35. 


.33. 


.31. 


.29. 


.27. 


.26. 


24 


48. 


.46. 


.44. 


.42. 


.40. 


.38. 


.36. 


.34. 


.33. 


.31. 


.29. 


.28. 


26 


49. 


.47. 


.45. 


.43. 


.41. 


.40. 


.38. 


.36. 


.34. 


.33. 


.31. 


.29. 


28 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2601 


(LIO) PREVENTION OF CONDENSATION 


(LlOa) General 

The condensation of moisture is an every day phenomenon 
causing more or less unsatisfactory conditions wherever it is 
not properly controlled. The control of condensation in indus- 
trial plants, where working conditions involve high moisture 
content of the air, is an important item in plant maintenance 
and employee health. In some types of plants, such as laun- 
dries, paper mills and bakeries, this is a necessary evil which 
can be eliminated only by great expense. In other types of 
industrial buildings such as textile mills or tobacco plants, a 
high moisture content of the air is absolutely essential to pro- 
vide proper working and conditioning factors. Modern build- 
ings are providing humidity control in order to maintain the 
higher relative humidity of the air required to promote comfort 
and health of occupants. These conditions require proper insu- 
lation against heat loss through the roof in order to prevent 
the condensation of moisture on these surfaces, which not only 
impairs the mechanical efficiency of the humidity control, but 
makes working conditions unsatisfactory, and adds unnecessary 
hazards to delicate equipment or material in process of manu- 
facture. 

It is common knowledge that condensation of moisture, 
that is, the forming of minute particles or drops of moisture 
upon a surface is caused by warm, moist air striking a colder 
surface and in so doing, precipitates the moisture content on 
the cold surface. The fundamental reason for this lies in 
the ability of air to hold only a certain quantity of moisture 
vapor in suspension at certain temperatures. Air at 100 de- 
grees Fahrenheit is capable of holding more moisture vapor 
in suspension than air at 75 degrees Fahrenheit. In this respect, 
air may be compared to a sponge, which when fully expanded 
is capable of holding a great deal more water than when it 
is partially contracted or squeezed. The cooling of air is 
comparable to the squeezing of the sponge. When air strikes 
a cold surface and is suddenly cooled, it is obvious that being 
unable to hold the water vapor in suspension, this water 
vapor is condensed into the form of moisture or drops of 
water which naturally form on the surface which has cooled 
the air. 

Obviously, the preventive for condensation lies in main- 
taining a surface warm enough so that it does not sufficiently 
cool the surrounding air to cause a depositing of moisture. 
Two general methods of providing proper temperatures of 
surfaces are possible— first, a high velocity of warm air played 
upon the colder surface will break down the surface film of 
still air lying directly over the surface of the material and 
so warm the surface that condensation cannot take place. 
This method is extremely expensive and in most cases imprac- 
tical. In stores, fans are oftentimes placed so as to play 
upon the show window glass area and are sufficient to keep 
the temperature of the inside glass surface above the con- 
densation point. The second method, and more practical one, 
is the proper insulation of the ceiling from exterior cold con- 
ditions so that the temperature drop from interior ceiling 
to interior air is not sufficient to bring the air to the point at 
which condensation will take place. 

The insulation of ceiling surfaces to prevent condensa- 
tion should be accomplished by the application of Weatherwood 
Roof Insulation on the exterior or coldest surface of the 
roof. This is always advisable since the mass of roof struc- 
ture is thus kept at a warmer temperature. Insulation against 
condensation is the reverse of insulating against heat loss, 
as regards the efYective location of the insulating material. 
It is best to eliminate as much volume to be heated as possible 
w'hen insulating to conserve heat. In the case of condensa- 
tion, it is desirable to keep the mass of roof structure as 
^yarm as possible, to give added insurance against condensa- 
tion. This is particularly true in frame construction as warm, 
moist air is liable to filter in behind the insulation, developing 
condensation on the interior of the wall structure. It is 
true in a lesser extent with masonry construction, as warm, 
moist air may find its way into crevices of the masonry. 

The problem of preventing condensation then, resolves 
itself into providing sufficient insulation to maintain proper 
interior temperature of wall or ceiling surfaces. The amount 
of insulating material required is governed by the relative 
humidity of the air inside and the range of exterior tempera- 


tures. For the convenience of those interested in the preven- 
tion of condensation, a chart is reproduced on page 23 giving 
an easy and quick method of determining the proper amount of 
Weatherwood required to offset various conditions. 

The determination of the amount of insulation required 
to prevent condensation under any specified condition is a 
simple mathematical computation. It is necessary, however, 
to understand clearly the factors involved in the computation. 

(LI Ob) Factors Involved 

(LlObl) Relative Humidity— This is the fi rst and prime 
factor to be given consideration in any condensation problem, 
because the relative humidity may or may not be changed in 
order to improve conditions. As stated in (LlOa), the hu- 
midity in an industrial structure sometimes is an unnecessary 
evil in which case it can be reduced somewhat by mechanical 
means or it may be an absolute necessity to provide proper 
working conditions. In any event, the humidity at which the 
structure will be used must be determined and this value used 
in the computation for required amount of insulation. 

Humidity is defined as the number of pounds of water 
carried as vapor by one pound of dry air. This definition 
refers strictly to water and air, as we are working with these 
mediums. Humidity is also used to denote the same relation- 
ship between any liquid vapor and dry gas. This relationship 
is often called absolute humidity. 

In the condensation problems we are primarily concerned 
with relative humidity. This is defined as the ratio between 
the amount of water vapor contained in the air at any given 
temperature to the amount of water vapor the same air would 
carry or hold at the same temperature if the air were satu- 
rated. That is, relative humidity is really an expression of 
the percentage of saturation existing in the air under any 
given condition. Exterior air is always partially saturated with 
moisture and a study of weather bureau reports shows that 
the humidity of the exterior air varies from hour to hour 
during the day. The average humidity for various parts of 
the United States taken at 8 A.M. ranges between 70% and 
85%, while the average humidity for the same locality at 
8 P.M. ranges between 50% and 75%. The reason for this 
lies in the heavy condensation of moisture on the earth's sur- 
face during the early hours of the morning with the resultant 
higher saturation of the lower strata of air during the early 
hours. As the sun and wind distribute this moisture, however, 
through the entire atmosphere and also as the air is warmed 
and expands, the relative percentage of saturation is reduced. 

Condensation problems are not concerned with exterior 
humidity conditions. The air within a structure may be en- 
tirely different as to percentage of saturation compared to 
exterior air. This percentage of saturation depends directly 
upon the processes of manufacture and the artificial humidity 
control provided within the structure. The following list of 
industrial plants indicates some of the types of plants in which 
condensation problems will be found and also gives the usual 
prevailing relative humidity for such plants. 

Type of Building Average Relative Humidity 

Laundries • 66% to 88% 

Dry cleaning plants 65% to 85% 

Paper mill roofs 70% to 85% 

Paper machine hoods 85% to 95% 

Textile Mills 65% to 85% 

Bakeries 80% to 90% 

Canning factories 70% to 85% 

Ripening and seasoning rooms 80% to 90% 

If it is impossible to make a check of humidity condi- 
tions, or for buildings under design, a relative humidity should 
be figured at about the maximum of the usual conditions as 
indicated by the above table. However, it is always advisable 
to make a check test to determine the relative humidity either 
on the structure under consideration or on a similar one. 

This test is simply a matter of obtaining dry-bulb and wet- 
bulb readings within the room. The dry-bulb reading is the 
ordinary thermometer temperature. This temperature should, 
however, be taken at a point as near the surface on which the 
condensation forms as possible. The wet-bulb reading merely 
means that the bulb of the thermometer is wrapped in a cloth 


Sweet's 


PAGE 21 


Continued on next page 


B2602 


Chicago Mill and Lumber Corporation 


or any material which will hold moisture so that the evapora- 
tion of this moisture affects the temperature reading of the 
thermometer. A simple method of obtaining this wet-bulb 
reading is to use an ordinary thermometer which has a cloth 
wrapped around the mercury bulb at the bottom. This cloth 
should be dipped in water at a temperature as near room tem- 
perature as possible. After thoroughly wetting the cloth, the 
thermometer itself should be whirled around in the air, either 
with the hand or on the end of a cord, so that the maximum 
evaporation effect can take place. Several such trials should 
be made until the lowest reading is obtained by this method. 
The difference between the wet-bulb and the dry-bulb reading 
is known as the wet-bulb depression. By referring this wet- 
bulb depression to table on page 20, the relative humidity of 
the air can be determined. 

(L10b2) Temperature Conditions— Next determine the 
maximum temperature difference between the interior tempera- 
ture and the coldest outside temperature at which it is ncessary 
to prevent condensation. If it is desired to prevent condensa- 
tion even on the very coldest days take the lowest outside tern- 
perature for the locality from weather bureau reports given in 
the table on page 19. 

If it is necessary to prevent condensation only on the aver- 
age cold days and a very slight amount of condensation would 
be permissible on the extreme cold days, a temperature of 15 or 
20 degrees above the lowest recorded temperature should be 
used. The difference between the inside temperature and this 
temperature is the figure to be used in the computation. 

(LlObS) Heat Resistance of Surface at which Conden- 
sation Takes Place— As stated in (LlOa) page 21, condensa- 
tion is due to the cooling of the interior air as it strikes the 
ceiling or under side of roof deck, which is colder. This dif- 
ference in temperature is due to the heat resistance of the sur- 
face, that is, the thin film of air which forms next to the 
surface and is stationary. This resistance will vary with dif- 
ferent types of surfaces, and as it is the drop in temperature 
across this surface resistance that causes condensation, the 
accurate value for the type of surface used must be obtained 
for the computation. The following is a table of surface con- 
ductivities as determined by Harding and Willard, taken from 
the Heating and Ventilating Engineer's Guide. 

Surface 

Building Material Coefficient 

Asbestos (sheet) 1-40 

Brick work (ordinary) 1-40 

Cement plaster (finished) 0.93 

Concrete ^-^^ 

Cork Board 1-25 

Glass 1-50 

Wood (finished surface) 1.40 

Average of all values 1-34 

The values quoted in the above table are given in B.t.u. 
per square foot of surface, per hour, per degree Fahrenheit 
difference in temperature. The average value of 1.34 is often 
used in computation in preference to a specific value for a 
definite material, particularly where no values are known for 
the material in use. Where surfaces are used, which are known 
to be much higher or lower than the average value, these defi- 
nite values should always be used. 

(L10b4) Determination of Dew Point— Condensation is 
caused by a cooling of the air to the point at which the air is 
totally saturated with moisture. For example, air at 60° F. 
and with a humidity of 90% will reach saturation, if cooled 3° 
and condensation will begin. The allowable drop in tempera- 
ture which will not bring saturation under any conditions of 
relative humidity and temperature, must now be determined by 
use of chart at bottom of page 23 as follows : Select the tem- 
perature along the bottom of the chart corresponding to the 
condition in the structure. Follow vertically upward on this line 
until an intersection is made with the horizontal line represent- 
ing the humidity within the structure. From this point, follow 
the curved lines up to the top of the chart. Along the top of 
the chart is a second temperature scale. The point on this scale 
intersected by the curved line is the dew point temperature. 
Subtracting this temperature from the original temperature 
gives the drop in temperature which will cause condensation. 
This drop in temperature is to be used in the computation of 
thickness of insulation required. 


(LlObS) Conductivity of Roof Deck Uninsulated— The 

final factor in making computation for the prevention of con- 
densation is the heat conductivity of the roof deck uninsulated. 
These values may be obtained by referring to table on page 18 
and selecting the type of structure to be used. 


(LlOc) MATHEMATICAL COMPUTATION OF 
CONDENSATION CONDITIONS 

Having definitely determined all of the factors which 
influence the results, these factors must be arranged in mathe- 
matical order for the final computation. 

The computation is as follows : First, compute the resist- 
ance of deck complete, without the insulation. This resistance 
is obtained by dividing the rated conductivity into one — that is : 
1 

= Resistance. Now divide the total temperature 

B.t.u. Rating 

difference by the conductivity of the surface film and divide 
again by the drop in temperature which will cause condensation 
of the moisture in the air. From this product subtract the 
resistance of the deck and multiply the difference by the con- 
ductivity of Weatherwood per inch of thickness (or .32). This 
gives the actual thickness of Weatherwood which will just 
prevent condensation under the condition stated. 

Example 

Same general conditions assumed as for typical analysis 
for fuel saving in (L9c) page 17. 

Inside temperature (operating condition) 65° F. 

Outside temperature — low S° F. 

Temperature difference 73° 

Relative humidity (near roof) 70% 

Conductivity of deck uninsulated 532 

Surface conductivity (using average value) 1.34 

Temperature drop across surface that will cause 
condensation (from chart at the bottom of 
page 23) 10.5° 

1 

Resistance of deck uninsulated = = 1.88 

.532 

73 1 

1.88 \ X .32= 1.05" 

J.34X10.5 J 

One inch of Weatherwood is sufficiently close to eliminate 
any condensation except on days with temperature below —8° F. 


(LlOd) GRAPHIC SOLUTION OF CON- 
DENSATION PROBLEMS 

The chart at the top of page 23 provides a quick and easy 
method of computing the amount of insulation required. This 
eliminates the necessity of mathematical computation and the 
necessity of referring to the psychometric chart to determine 
the temperature drop permissible, so that a complete solution 
is provided in one operation. This is done as follows : Select 
on the inside temperature scale at the upper left edge of the 
vertical center line the temperature for the building in ques- 
tion. From this point, pass horizontally to the left to an inter- 
section with the line representing the relative humidity. From 
this point, pass vertically down to the diagonal line represent- 
ing the temperature difference (inside maximum and outside 
low). From this point, pass horizontally over to the diagonal 
line representing surface coefficient. From this intersection, 
pass vertically up until an intersection is made with the hori- 
zontal line representing conductivity of uninsulated deck. If 
this intersection point falls close to one of the Weatherwood 
lines, the thickness represented by the line will prevent con- 
densation. If the intersection falls between Weatherwood lines, 
the next line representing the next greater thickness is the 
amount of Weatherwood necessary. 

It is obvious that a complete reversal of the method can 
be used to determine the relative humidity a certain deck and 
certain amount of insulation will support. For an uninsulated 
deck start at the conductivity of the deck located on the hori- 
zontal scale at the center of the chart. 


Sweet's 


PAGE 22 


Continued on next page 


Chicago Mill and Lumber Corporation 


B2603 


CHARTS FOR GRAPHIC SOLUTION OF CONDENSATION PROBLEMS 


reMPEBATUffC or AIR or Onr-BULQ THEHMOMCTEFi^'r IN D56RC€5 FAHRENHCIT 


Sweet's 


PAGE 23 


Continued on next page 


B2604 


Chicago Mill and Lumber Corporation 


(M) WEATHERWOOD SOUND DEADENING CONSTRUCTION 


(Ml) The Need for Sound Deadening 

Although much stress has been laid upon the strength 
and fire resistance of buildings, and within later years, upon 
the insulation of buildings to stop heat loss, very little atten- 
tion has been paid to the importance of insulating against sound 
passing between adjoining rooms or apartments. 

It is only too true that in many apartment buildings today, 
ordinary conversation in one apartment can be heard in ad- 
joining apartments. Consider then, how much more disturbing 
it must be when there are noises in one apartment which are 
considerably louder than the ordinary spoken tone. What is 
true in apartment buildings is equally true in offices and indus- 
trial buildings. Laboratory research shows that noise reduces 
personal efficiency from five to thirty per cent, depending upon 
the occupation of those affected. 

Dr. Donald A. Laird, Director of the Psychological Labo- 
ratory of Colgate University, says, "Many executives think 
that noise is inevitable, that nothing can be done to lessen it, 
and that any way it does not matter. All three ideas are 
wrong. Noise cuts into dividends by lessening output and 
requiring more energy from workers. There is no evidence 
that workers get used to noise. They may become unconscious 
of its presence, but the effect upon their output remains. 

"In the Colgate University Laboratory, it was determined 
by the use of special apparatus that noise of usual office inten- 
sity cuts into the output of professional typists on the average 
of 5 per cent. In higher mental work, such as the executive 
does, the cut into output is in the neighborhood of 30 per cent. 

"In a survey of two large plants conducted by the United 
States Public Health Service, it was found that labor turnover, 
absence from work, and requests for transfer to other work 
were above the plant average in those departments which were 
noisy." 

Owners and operators of apartment buildings and apart- 
ment hotels are today finding that effective sound deadening 
between rooms or apartments is an important factor in leasing 
and filling these buildings. In many cases apartments have 
been rented on the supposition that they were soundproof, be- 
cause of the fact that they were built along heavy construction 
lines. Later, occupants have found, to their sorrow, that this 
did not solve the problem and that they were much disturbed 
by occupants of adjacent apartments. 

There are many points at which sound deadening is neces- 
sary. These points include the transmission of sound between 
offices, apartments or studios; transmission of sound between 
reception rooms and consultation rooms ; transmission of sound 
between floors; transmission of sound between rooms and 
adjacent elevator shafts; transmission of sound from mechan- 
ical and ventilating equipment ; transmission of sound between 
manufacturing and office space in industrial buildings; trans- 
mission of sound between kitchens or equipment rooms and 
patients* rooms of hospitals. 

The purpose of this Division is to give briefly the important 
facts to be considered on the subject of sound deadening. 

Definite suggestions are made as to various methods of 
obtaining sound deadening of wall or floor sections, and dia- 
grams indicate the construction suggested. 

Scientists agree that a material which in itself will absorb 
a certain amount of sound and can be used in a structural 
way, is well adapted for use in sound deadening construction. 
This is quite true of Weatherwood, an insulating board fabri- 
cated from hardwood. The Manufacturing Process (A) pages 
1 and 2 and the Physical Characteristics (B) pages 2, 3 and 4 
clearly indicate why Weatherwood is readily adaptable for 
sound insulation, as well as for heat insulation. 

(M2) The Problem of Sound Deadening 

The general problem of insulation or isolation of sound 
does not differ greatly from the problems encountered in the 
insulation of heat. In both cases is is a form of energy that 
is being dealt with and, in both cases, it is an economic impos- 
sibility to prevent entirely the transmission of such energy. 
Modern demand for higher standards of living are just begin- 
ning to be felt in the sound deadening field. Sound filters 
through loose and flimsy construction just as heat filters 
through. Consequently, the problem of sound insulation ulti- 
mately resolves itself into the same thorough attention to detail 
as is necessary where efficient heat insulation is required. 

It so happens that the same characteristics which make 
certain materials good heat insulators, make them peculiarly 
adaptable and efficient in the insulation of sound. The fol- 
lowing data outlines briefly how sound is insulated or isolated 


and at the same time shows clearly why Weatherwood pro- 
vides good sound deadening results and how it should be 
employed to do so. 

(M3) Sound Transmission 

The insulation of sound really divides itself into two 
separate problems based on the origin of the sound. There 
are two distinct types of sound. First, those sounds which 
originate in or are produced first in air; second, impact or 
tapping sounds, such as sounds produced when a solid wall 
or metal pipe is struck by a hard object. The transmission 
of both of these types of sound takes place through all physical 
mediums, no physical substance being entirely resistant to 
sound transmission. One kind of sound insulation, however, 
will not produce equal results with both types of sound and 
different methods must be employed when insulation for both 
types is required. 

Sound is transmitted first by conduction, and second, by 
vibration of solid bodies or areas. The conduction of sound 
is effected by the transfer of sound energy from particle to 
particle of any substance and in the case of many materials, 
with only a little loss of original intensity. This phenomena 
of sound transmission is similar in results to the transmission 
of heat energy, or for that matter any form of energy transfer 
by conduction. In the case of sound energy, a vibration is 
set up in the particle immediately adjacent to the source of 
sound and this vibration is reproduced in each succeeding 
particle in contact. Different materials have different rates 
or velocities at which the transmission of sound through them 
will take place. Generally speaking, those materials with low 
velocity of sound transfer are better for sound insulation. 
As in the case of heat transfer, air and other gases have a 
comparatively lower transfer rate than solids, such as wood or 
steel. The following brief table is indicative of the nature of 
transmission of sound by conduction through materials. 


VELOCITIES OF SOUND (Approximate Values) 


Substance 


Velocity in feet 
per second 


Reported 


Aluminum 

Gold — soft 

Lead 

Poplar — along the fiber... 
Brick 

Water 


16,740 
11,670 
5,717 
16,320 
4,026 
12,140 
177 
10,900 
14,050 
11,980 
1,087 
1,609 
1,315 


Masson 

Wertheim 

Wertheim 

Wertheim 

Wertheim 

Wertheim 

Exner 

Wertheim 

Wertheim 

Chladni 

Violle 

Zoch 

Masson 


The second method of sound transmission is by means of 
vibrating bodies or areas. This type of sound transmission 
is illustrated by the use of sounding boards. In this type of 
transmission, the sound may either originate as an air borne 
or an impact sound, but results in the setting up of vibrations 
of an entire area or panel, the original sound having set this 
panel into vibration. The vibration of the panel itself repro- 
duces and transmits the original sound into the next medium 
by its vibration. A body having a large area as compared 
to volume has a marked tendency to transmit sound by vibra- 
tion, as compared to those bodies having a large volume and 
small areas. Thin bodies have a tendency to increase their 
vibration effect as the area increases. Thin, vibrating panels 
vary in transmission of sound in proportion as their total 
area is increased and also as the rigidity of the fastening of 
the edges is lessened. In other words, rigid fixing of the 
edges of thin panels, aids in preventing the transmission ot 
sound through such a panel. 

After consideration of the methods by which sound is 
transmitted, it is obvious that the chief difference between 
air borne sound and impact sound, as regards their insula- 
tion, lies chiefly in the comparative intensities of such sound. 
In other words, air borne sounds have had the deadening and 
what is more important, the diffusing influence of the volume 
of air in which they originated, while the impact sounds are 
transmitted practically in their initial intensity with none 
of the reducing effects of diffusion in surrounding media or 


Sweet's 


PAGE 24 


Continued on next page 


Chicago Mill and Lumber Corporation 


deadening by passing through low velocity material. It is 
obvious from this that air borne sounds having an intensity 
exactly equal to impact sound, as they both strike a trans- 
mitting medium or material, would require very much the same 
insulation design for proper deadening. However, this is 
very rarely the case, and air borne sounds reach the separat- 
ing wall, floor, or structure, usually at a greatly reduced 
intensity as compared to the intensity of impact sounds. Gen- 
erally speaking, then, it is obvious that impact sounds will be 
found to be much more diflicult to insulate than those which 
are air borne. For that reason sound deadening construc- 
tion is particularly valuable in apartment buildings, hotels, 
hospitals, public buildings and industrial buildings. 

(M4) Destruction of Sound Energy 

Sound is a form of encri^y and the fundamental physical 
laws tell us that energy is never destroyed, but is merely 
stored in one form or another. The destruction, therefore, 
of sound energy involves a change into some other form. Tn 
other words, sound is capable of doing work and the per- 
formance of this work must be pertnittcd in such a way that 


the original sound is dissipated or transformed into heat to the 
greatest possible extent, thus preventing the transmission of the 
original sound into those spaces which are to be insulated. 
Those materials which have a low velocity rate for the trans- 
mission of sound obviously assure greater dissipation of sound. 
This greater resistance may be compared to electrical resist- 
ance, that is, the resistance built up by low transmission rate 
materials transforms more of the original sound into heat 
thus changing its original form. The destruction, therefore, 
of sound energy requires the use of "dead" or low trans- 
mission rate materials in the arrangement of materials through 
which the sound must pass. Jt is at the same time obvious 
that if comparatively "dead" materials arc used in large, thin, 
section areas, a tendency to transmission by vibration is cre- 
ated. A combination structure must, therefore, be provided, 
which gives in the first place rigidity, to prevent transmissicm 
by vibration and in the second place, involves the use of a 
"dead" material to assist in the destruction of sound energy. 
A complete treatise, "The Weatherwood Handbook of Sound 
Deadening Construction" will be sent on request to anyone 
interested. 


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SOUND DEADENING CONSTRUCTION DETAILS 


Sweet's 


PAGE 25 


Weatherwood 

Insulation Data Book 

for 

Architects 


INSULATION DIVISION 


(HICAGO M'LL iJiP |UMBER QrPORATION 


111 West Washington Street 
CHICAGO JLLINOIS 


Digitized by: 


INTF RNATION Al 

ASSOCIATION 

FOR 
PRESERVATION 
TECHNOLOGY, 
INTERNATIONAL 
www.a pti.or g 


BUILDING 
TECHNOLOGY 
HERITAGE 
LIBRARY 

h ttps://archive.org/d e tails/buildingtechnolog yheritagelibrary 


From the collection of: 
Robert Vail Cole Jr, AIA 
1962-2011 


Weatherwood 

Insulation Data Book 

for 

A 1 


(hicago Mill an? [umber Corporation 

111 West Washington Street j 
CHICAGO, ILLINOIS