BUILDING MATERIALS AND STRUCTURES REPORTS

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The following publications in this series are available by purchase from the Superiatendent of Documents at the prices indicated :. BMSl Research on Building Materials and Structures for Use in Low-Cost Housing 10^ BMS2 Methods of Determining the Structural Properties of Low-Cost House Constructions. . 10(4 BMS3 Suitability of Fiber Insulating Lath as a Plaster Base 10(4 BMS4 Accelerated Aging of Fiber Building Boards 10(4 BMS5 Structural Properties of Six Masonry Wall Constructions 15^ BMS6 Survey of Roofing Materials in the Southeastern States 15(i BMS7 Water Permeability of Masonry Walls 10j4 BMS8 Methods of Investigation of Surface Treatment for Corrosion Protection of Steel 10(4 BMS9 Structural Properties of the Insulated Steel Construction Co.'s "Frameless-Steel" Constructions for Walls, Partitions, Floors, and Roofs 10(4 BMSlO Structural Properties of One of the "Keystone Beam Steel Floor" Constructions Sponsored by the H. H. Robertson Co 10^ BMSll Structural Properties of the Curren Fabrihome Corporation's "Fabrihome" Constructions for Walls and Partitions 100 BMS12 Structural Properties of "Steelox" Constructions for WaUs, Partitions, Floors, and Roofs

Sponsored by Steel Buildings, Inc 150 BMS13 Properties of Some Fiber Building Boards of Current Manufacture 100 BMS14 Indentation and Recovery of Low-Cost Floor Coverings 100 BMS15 Structural Properties of "Wheeling Long-Span Steel Floor" Construction Sponsored by

Wheeling Corrugating Co 100 BMSl6 Structural Properties of a "Tilecrete" Floor Construction Sponsored by Tilecrete

Floors, Inc 100 BMS17 Sound Insulation of Wall and Floor Constructions 100 Supplement to BMS17, Sound Insulation of Wall and Floor Constructions 50 BMS18 Structural Properties of "Pre-Fab" Constructions for Walls, Partitions, and Floors Sponsored by the Harnischfeger Corporation 100 BMS19 Preparation and Revision of Building Codes ^ 150 BMS20 Structural Properties of "Twachtman" Constructions for Walls and Floors Sponsored by

Connecticut Pre-Cast Buildings Corporation 100 BMS21 Structural Properties of a Concrete-Block Cavity-Wall Construction Sponsored by the National Concrete Masonry Association 100 BMS22 Structural Properties of "Dun-Ti-Stone" Wall Construction Sponsored by the W. E. Dunn Manufacturing Co 100 BMS23 Structural Properties of a Brick Cavity-Wall Construction Sponsored by the Brick

Manufacturers Association of New York, Inc 100 BMS24 Structural Properties of a Reinforced-Brick Wall Construction and a Brick-Tile CavityWall Construction Sponsored by the Structural Clay Products Institute 100 BMS25 Structural Properties of Conventional Wood-Frame Constructions for Walls, Partitions,

Floors, and Roofs 150 BMS26 Structural Properties of "Nelson Pre-Cast Concrete Foundation" Wall Construction

Sponsored by the Nelson Cement Stone Co., Inc 100 BMS27 Structural Properties of "Bender Steel Home" Wall Construction Sponsored by The

Bender Body Co 100 BMS28 Backflow Prevention in Over-Rim Water Supplies 100 BMS29 Survey of Roofing Materials in the Northeastern States 100 BMS30 Structural Properties of a Wood-Frame Wall Construction Sponsored by the Douglas

Fir Plywood Association 100 BMS31 Structural Properties of "Insulite" Wall and "Insulite" Partition Constructions Sponsored by The Insulite Co 150 BMS32 Structural Properties of Two Brick-Concrete-Block Wall Constructions and a Concrete- Block WaU Construction Sponsored by the National Concrete Masonry Association. 100

[List continued on cover page iii]
UNITED STATES DEPARTMENT OF COMMERCE • Jesse H. Jones, Secretary

NATIONAL BUREAU OF STANDARDS • Lyman J. Briggs, Director

BUILDING MATERIALS

and STRUCTURES

REPORT BMS85

Dimensional Changes of Floor Coverings with Changes in Relative Hvimidity and Temperature

by

PERCY A. SIGLER, ROBERT I. MARTENS, ^7/?^ ELMER A. KOERNER

ISSUED JULY 15, 1942

The National Bureau of Standards is a fact-finding organization;

it does not "approve" any particular material or method ot construction. The technical findings in this series ot reports are to be construed accordingly.

STATES GOVERNMENT PRINTING OFFICE • WASHINGTON • I 94

BY THE SUPERINTENDENT OF DOCUMENTS, WASHINGTON, D. C. • PRICE lO CENTS

UNITED

FOR SALE
Fo reword

Investigations of important properties of floor coverings have

been made at the National Bm'eau of Standards as part of a research

program on building materials suitable for low-cost house construction. This report contains information and data on the effects of changes in relative humidity and temperature on the dimensions of

floor coverings.

Lyman J. Briggs, Director,

[111
Dimensional Changes of Floor Coverings With Changes in

Relative Humidity and Temperature

hy PERCY A. SIGLER, ROBERT I. MARTENS, and ELMER A. KOERNER

CONTENTS

Page

Foreword ii

I. Introduction 1 II. Test procedure and equipment 2

1. Specimens exposed to different rela- tive humidities 2

2. Specimens exposed to different temperatures 3

Page

III. Description of materials tested 4

IV. Results 5

1. Effect of relative humidity on di- mensions 5

2. Effect of temperature on dimensions. 6 V. Summary and conclusions 7

ABSTRACT

The effects of changes in atmospheric conditions on

the dimensions of floor coverings were investigated.

The floor coverings tested included such general types

as linoleum, cork, rubber, felt base, asphalt, strip wood,

plywood, fiberboard, and several monolithic compositions, such as cement mortar and magnesium oxychloride. Dimensional changes due to a variation in relative humidity from 8 to 86 percent and those due

to a variation in temperature from 32° to 90° F were

determined. The floor coverings, testing equipment,

and procedure are described, and the results are pre- sented in graphic form. Changes in relative humidity affect the dimensions of many floor coverings to a much greater extent than do

changes in temperature within the range usually en- covmtered in structures. Such floor coverings as strip

wood, linoleum, and felt base show a much greater di- mensional change in the across-grain or across-machine

direction than in the grain or machine direction. The

several monolithic compositions showed relatively small changes in dimensions.

I. INTRODUCTION

The tendency of floor coverings to expand or contract with changes in moisture content and

temperature is an objectionable characteristic.

These changes are most commonly dependent

upon the relative humidity and temperature of

the smT0U2idmg air and thus have a limited

range in many locations. However, in some

locations extreme conditions are often encoiuitered, such as large temperature changes

near heating equipment or prolonged exposure to water in basements.

Excessive expansion or contraction of floor covermgs after being installed is likely to result

in one or more of the following objectionable

conditions: loosening of bond to subfloor,

separation witliin floor covering, buckling, curling, separation at joints, or splitting. Small

dimensional changes may cause appreciable

buckling or eurlmg, and therefore these conditions are frequently encomitered in many floor covermgs. This can be readily understood if one considers the smaU dift'erence which exists

between the lengths of an arc typical of a dis- tortion, and its subtended chord. Unequal

dimensional changes of the top and bottom

surfaces due to dift'erence of exposure are contributing factors, especially with floor coverings

installed in small units.

The dimensional changes of subfloors, especiafly those of strip wood, due to seasonal changes

in mdoor relative humidity are undoubtedly

often the principal cause of a premature failure or unsatisfactory performance of a floor covering. The expansion or contraction of strip

wood in the across-grain dnection with change

in moisture content is considerable. A felt underlay is frequently used with thui floor cover462358°-42 [1]
^'iGURB I.

Conditioning cabinet and hntance.

ings over sirip-wood subHours. It acts as a

yielding cusliion between the subfiooi- and floor covering, and aids in maintaining an even

surface and thus uniform distribution of wear. Except foi- the test method and Hmit for curling included in Federal Specification SS-T306 for asphalt tile, little attention has been paid

in specifications for flooring materials to dimensional changes. A study was therefore made of the eft'ects of relative humidity and temperature on the dimensions of floor coverings. Such

information should be of interest to the manufactui-ei'S and installers of floor coverings in the

proper recommendation and installation of their merchandise, and also of aid to the con- sumer in the selection and care of floors, especially where ujuisual conditions may prevail.

The results of studies of other properties of

floor coverings and adhesives have been published in Building Materials and Structures

Reports BMS14, BMS34, BMS43, BMS59,

BMS68, BMS73, and BMS80. (See cover pp.

II and III.)

II. TEST PROCEDITRE AND EQUIPMENT

1. Specimens Exposed to Different Relative Humidities

For determining the dimensional changes of

floor coverings with changes in the relative

humidity of the surrounding air and thus

changes in the moisture content of the floor coverings, specimens were conditioned and

measured first at 65-percent, then at 8-percent,

again at 65-percent, and finally at 86-percent

relative humidity. The temperature was maintained at approximately 72° F throughout these

determinations. With the exception of the

strip-wood flooring, the specimens were 9 by 9

in. The strip-wood specimens were 1% by 9 in. The specimens were weighed from time to time

under each of the atmospheric conditions as an

ijidication of the approach to and attainment of moisture equilibrium. An exposure of at

h'ast 2 weeks was found necessary for most of the floor coverings to reach equilibrium.

Some required a much longer time.

A conditioning room at the Bureau provided an atmosphere maintained at 65-percent rela- tive hurxiidity and 72° F. Atmospheres of

8 it 3 percent and 86 ±2 percent relative humidity were obtamed in a small cabinet es- pecially constructed for the purpose. (See fig.

1.) The size of the cabinet was sufficient to hold several specimens, with one specimen at a time suspended by a wire from the weighing

])an of an analytical balance. By means of

l)allles and a motor-driven fan, air was circulated around the specimens and over a tray

containing the conditioning medium. Anhydrous calcium cldoride was used to obtain 8- percent relative humidity and a saturated

solution of zinc sulfate to obtain 86 percent.

The atmospheric conditions in the cabmet

were determined from the I'eadings of wet- and

diT-bulb thermometers placed directly below

the fan. In order to measure a specimen con-

[2]
ditioned in the small ctibinet, it was necessary

to move it into an atmosphere of 65-percent

relative humidity. Measurements of a specimen were started immediately and were completed within half an hour. The dimensions

remained practically unchanged for that length

of time, inasmuch as check measurements made

at the end of the period were the same as those

obtained at the beginning of the period.

The dimensional changes of the 9 by 9-in. specimens were determined from measure- ments made with a micrometer comparator.

(See fig. 2.) The instrument consisted essentially of an Invar-steel bar on which were mounted two low-powered microscopes equipped

with filar micrometers. The microscopes were clamped on the bar so that corresponding

graduations of the two micrometers were 8 in. apart. The distances between reference marks,

approximatelj^ 8 in., were m^easured to the nearest 0.001 in. Twelve separate measure- ments were made on each specimen—three in the machine or grain direction and three in the

across-machine or across-grain direction on

both the face and the back of the specimen.

In order to be certain that a specimen was

flat when being measured, it was placed on

a glass plate and weighted down with a

steel plate 7 m. square and in. thickThe dimensional changes of the strij)-woo(l

flooring in the across-grain direction were determined from measurements made with ii micrometer caliper having a range of 1 to 2 in.

2. Specimens Exposed to Different Temperatures

For dctermhiing the dimensional changes of

floor coverings with changes in temperature,

specimens were conditioned and measured first at 72°, then at 32°, again at 72°, and finally at 90° F. The relative humidity of the sur- rounding air was maintained at approximately

65 percent throughout these determinations.

The variation in relative humidity at 72° and

90° F was ±2 percent; the variation at 32° F

was ±4 percent. Various conditioning rooms

at the Bureau provided the above atmospheres.

The specimens were weighed under each of

theii- various conditions as a check on their

moisture content remaining constant. Even

though the relative humidity was maintained

approximately constant, the weights, and thus

the moisture contents, of the materials varied

somewhat. In general, the specimens weighed

slightly more at 32° than at 72° F and slightly

less at 90° than at 72° F. The size of the
specimens and the manner of measming were

similar to those used in the exposures to different

relative humidities.

III. DESCRIPTION OF AIATERIALS

TESTED

The floor coverings tested included such

general types as linoleum, cork, rubber, felt base, asphalt, strip wood, plywood, fiberboard,

and several monolithic compositions. They

are listed in table 1, along with their changes

in weight in conditioning from 65- to 8-percent

relative humidity and from 65- to 86-percent

relative humidity at 72° F. The generous co- operation of variovis manufacturers in furnishing

materials for test is gratefully acknowledged.

Table 1.Floor coverings tested and the effect of chnnge

in relative humidity on their weight

Table 1.Floor coverings tested and the effect of change

in relative humidity on their weight—Continued

Sample number

Floor covering

Type and description

1..

2..

3_.

4.. 5-

6..

7_-

8-.

9__

10

11.

12

13

14

15

16

17

18.

19

20.

21.

Battleship linoleum; plain pattern, brown

Battleship linoleum; plain pattern, gray

Battleship linoleum; plain pattern, green Marbleized linoleum; marbleized

pattern, tan Marbleized linoleum; marbleized

pattern, white

Jaspe linoleum; jaspe pattern, brown

Inlaid linoleum; molded pattern, gray Printed linoleum: block pattern, brown; wearing surface, enamel- Cork-composition tile; plain pattern, gray Cork tile;'' light shade; density,

30 lb/ft.3 = Cork tile;<' light shade; density, 37

lb/ft.' <^ Felt-base; inlaid pattern, gray; wearing surface, linoleum composition

Felt-base; inlaid pattern, cream: wearing surface, linoleum composition

Felt-base; jaspe pattern, brown;

wearing surface, cellulose nitrate composition

Felt-base tile; jaspe pattern, green; wearing surface, cellulose nitrate composition

Felt-base; mottled pattern, tan; wearing surface, resin and drying

oil composition

Felt-base; mottled pattern, gray; wearing surface, resin-treated

cotton-linters sheet

Felt-base; mottled pattern, white; wearing surface, resin-treated

cotton-linters sheet Felt-base tile; plain pattern, red; wearing surface, asphalt and

pitch composition

Felt-base; plain pattern, maroon;

wearing surface, asphalt and

pitch composition ._ Felt-base; printed pattern, brown;

wearing surface, enamel

Change in weight from

65-percent rela- tive humidity

at 72° F to—

Nominal

thick- ness

8-per- cent

relative humidity

86-per- oent

relative humidity

in. %

-2. 26 %

-1-2.08

H — 1. 80 -|-1. 79

'A -1.98 -f-1.70 H —2. 24 -t-2. 30 H -1.42 -fl.82 H2 —2.41 +1.93

-2. 05 +2. 06 —2. 36 +1.78 H -1. 50 +1.43

-1.88 +1.88

5-! 6 -2. 15 +2. 46

ret

5fi4 -1.85 +1.86

H4 -2.56 +2. 21

lU -2. 18 +2.38

Hi -2. 60 +2. 22

He -LSI +2.40

Hi -L89 +L79

^64 -1.75 +2. 11

%3 -1.68 +L84

'At -L74 +L88

Sample number

23- -

24- .

25..

26.-

27- .

28- .

29-

30-

31-

32-

33

34-

35-

36-

.39.

40-

42-

43-

44-

45-

46- .

47- .

48- .

49-

50-

51-.

52-

Floor covering

Type and description

Felt-base; printed pattern, red; wearing surface, enamel

Sheet rubber; marbleized pattern, brown Rubber tile; marbleized pattern, gray Rubber tile; black; contained aluminum oxide aggregate Asphalt tile; iilain iwltcrn, black; 1-minute indcnlatioii, 0.010 in.^ - Asphalt tile; marl'leizcd pattern, white; 1-minute indentation,

0.006 in.« Asphalt tile; plain pattern, mahogany; 1-minute indentation,

0.009 in. = Asphalt tile; plain pattern, mahogany; 1-minute indentation,

0.010 in.e Asphalt tile; plain pattern, white; 1-minute imlcntut icjn, 0.008 in.e. Asphalt tile; plain pattern, white; 1-minute indentation, 0.010 in.'. Asphalt tile; plain pattern, red; 1- minute indentation. 0.007 in.«-- Asphalt tile; plain pattern, maroon; contained asphalt-roofing

material; 1-minute indentation,

0.011 in.«- 1:2 cement-mortar topping; ag- gregate, Potomac-River sand;

density, 137 Ib/ft.s ^ Magnesium-o.xychloride composition; plain pattern, red; aggregate, calcite dust; density, 108

Ib/ft.s " Magnesium-oxychloride composition; plain pattern, green; aggregate, granite dust; density, 118

lb/ft.3 c Magnesium-oxychloride composition; iilain pattern, green; aggregate, inartile ilust, cotton fiber, and copper pciwder; density, 108

lb/ft.3 = Alumina cement-rubber latex composition; terrazzo pattern, green;

aggregate, marble chips; density

131 lb/ft.3 " Coal-tar mastic composition; plain

pattern, gray; aggregate, gravel, sand, and gypsum; density, 128

lb/ft.3 = Asphalt-impregnated fiberboard

tile; plain pattern, dull black; density, 57 lb/ft. ^ 0 Asphalt-impregnated fiberboard

tile; plain pattern green; density,

54 lb/ft.3 " Pressed fiberbord tile; brown;

density, 67 Ib/ft.s <^ Rock-elm plywood tile;'' 3-ply Douglas-fir plywood;<i 5-ply Short-strip maple;'' flat-grained; density, 44 lb/ft. 3 Short-strip maple;'' flat-grained; density, 47 Ib/ft.s Strip white oak;^ flat-grained; density, 40 Ib/ft.s c Short-strip pecan;'' flat-grained; density, 40 Ib/ft.^ ' Strip yellow pine;'' flat-grained; density, 44 lb/ft. ' " Strip Douglas fir;'' edge-grained;

density, 36 lb/ft. s • -. Strip Douglas fir;'' edge-grained;

density, 27 Ib/ft.s ^ Plywood underlay; 3 plies of hard- wood veneer with asphalt- saturated paper on both faces,.

Nominal

thick- ness

H

Via M

Me

Change in weight from

65-percent rela- tive humidity

at 72° F to—

8-per- cent

relative humidity

86-per- cent

relative humidity %

-1.78 %

+1.93 -0. 40 +0. 31 -. 24 +. 26 -.48 +.55

-. 18 +. 45

-.21

-.24

-.21 -.36

-. 27 -.18

-. 15

-2.33

-1. 63

-2.61

Vi -1.51

2^^2 2^2

Me

-.29

-1. 23

-1.45

-4. 39

-5. 66

-7. 70

-7.41

-6. 82

-6.97

-5. 81

-6. 10

-5. 07

-6.03

+L76

+3. 21 +5.63

+5. 00 +7.64

+7. 72

+5. 98

+5. 18 +5.62

+5. 01

+3. .59

24 +4. 40

» Color listed in the predominating color.

i> Factory-applied finishing material on surface.

I' .A.t 65-pereent relative humidity and 72° F.

'' No finishing material on surface.

' Method prescribed in Federal Specification SS-T-306, Tile; Asphalt.

[4]
IV. RESULTS

1. Effect of Relative Humidity on

Dimensions

The effects of changes in relative humidity

from 65 to 8 percent and from 65 to 86 percent on the dimensions of the floor coverings listed

in table 1 are shown graphically in figures 3 to

7, inclusive. The dimensional changes are re- ported as the percentage change from the di- mensions at 65-percent relative humidity and

72° F. The unshaded blocks show the dimensional changes in the machine or grain direction on all samples where the direction could be

ascertained. The shaded blocks show the

dimensional changes in the across-machine or

across-grain direction or at right angles to the

first direction. The values reported represent

the average of the several separate measure- ments made on both the face and the back of

the specimens.

Dimensional changes occurred in some floor coverings opposite to that which might be ex- pected; the amounts are shown by broken lines

01-

0.6 OS

OA

0.3

5^

' 0.2 w

2 0./ <

io.i o

5 03

0.4

O.S

0.6

0.7

4

2 4-567

SAMPLE NUMBER

10 II

86% RH

65% RH

V

8%RH

Figure 3.

Effect of relative humidity on dimensions of

linoleii ms, cork-composition tile, and cork tiles. Samples 1 to 8, linoleum; 9, cork-composition tile; 10 and 11. cork tile

0.5

0.4

. 0.3

.0.^

< 0.1 Io +

0

0.1 o

inz 0.2

UJ2

5 0.3

0.4

0.5

I I

r II

i

n

RH

65% RH

Y8%

R H

IZ /3 /4 15 16 n li SAMPLE NUMBER

19 20 2/ 22

Figure 4.

Effect of relative humidity on dimensions of

felt-ba.se floor coverings having various wearing

surfaces. Wearing surface of samples 12 and 13, linoleum composition; 14 and 16, cellulose nitrate composition; 16, resin and drying oil composition; 17 and

18, resin-treated cotton-linters sheet; 19 and 20, asphalt and pitch composition; 21 and 22, enamel.

in the charts. These reversals occurred only

as contractions in the machine direction when

the specimens were expanding in the aci"Oss- machine direction and, to any appreciable extent, only with materials having a fabric backing. Stresses of an opposite nature and of

greater magnitude than those due to moisture were probably created in the machine direction

OS

0,4

0.3-

>0.Z

< 0.1 Io +

2 0.1 o

(nzO.Z

UJo0.3

0.4

0.5

86%

R H

69/. R H

8%

R H

23 24 25 26 27 Z8 29 30 31 32 33 SAMPLE NUMBER

Figure 5.

Effect of relative humidity on di mensions of

sheet rubber, rubber tiles, and asphalt tiles. Sample 23, sheet rubber; 24 and 25, rubber tile; 26 to 33, phalt tile.

[S]
34- 3S 36 37 38 39 40 4/ 4^ 43 44

SAMPLE NUMBER

Figure 6.

Effect of relative humidity on dimensions of monolithic compositions, fiberboards, and plywoods.

Sample 34, ceraent-mortar topping; 35 to 37, magnesium oxyciiloride composition; 38, alumina cement-rubber latex composition; 39, coal-tar mastic composition; 40 to 42, flberboard; 43 and 44, plywood.

of the specimens by the considerable expansion

in the across-machine direction. A backing

fabric might be expected to aggravate such a

condition.

3.2

2.8

2.4

2.0

/.6

I 0.8

UJ

e)< 0.4 5 +

0

2 0.4 o

§0.8

UJS5 I.Z

1.6 to

2.4h

I

^1

il

45 46 47 4 8 49 50 5/ SAMPLE NUMBER IT

S6X

R H

65%

R H

Y

8%

R H

Figure 7.

Effect of relative humidity on dimensions of stripwood floorings and plywood underlay.

Note.—Scale is 4 times that used in other charts. Samples 45 and 46, maple; 47, white oalv; 48, pecan; 49, yellow pine; 50 and 51, Douglas fir; 52, plywood underlay.

2. Effect of Temperature on Dimensions

After a number of samples had been tested,

it became apparent that the effect of temperature on the dimensions of floor coverings was

small in comparison with the effect of relative

humidity and from a practical viewpoint was

relatively of little importance. In view of this and the difficulty of maintaining the moisture

content of the specimens absolutely constant

at different temperatures, this phase of the in- vestigation was somewhat curtailed. In order

to give a conception of the magnitude of the

changes involved, the effects of changes in

temperature from 72° to 32° F and from 72°

to 90° F on the dimensions of several different

floor coverings are shown graphically in figure

8. The dimensional changes are reported as percentage changes from the dimensions at 72° F and 65-percent relative humidity. Dimensional changes in the machine direction for the linoleums and felt-base materials were ex- tremely small and frequently opposite to the

changes in the across-machine direction. The

amounts were about the same in magnitude as the uncertainty of the measurements—that is, about 0.001 in., or 0.01 percent.

/ 7 /4 20 2/ 23 24 26 27 28 29

SAMPLE NUMBER

Figure 8.

Effect of temperature on dijuensions of floor coverings.

Samples 1 and 7, linoleum; 14, 20, and 21, felt base; 23 and 24, rubber;

26, 27, 28, and 29, asphalt tile.

[6]
V. SUMMARY AND CONCLUSIONS

The magnitude of the expansion or conti'action of many floor coverings is much greater

for changes in moisture content than for changes in temperature within the Hmits of ordinary atmospheric conditions. The dimensions of asphalt-tUe and rubber floor coverings

are not appreciably affected by changes in

either relative humidity or temperature.

In many floor coverings there is a pronounced

difference in the dimensional change for differ- ent directions. For normal changes in moisture

content, the dimension in the across-grain or across-machine direction of such floor coverings

as strip wood, linoleum, and felt base is affected

to an appreciable extent, whereas in the grain

or machine direction the change in dimension

is negligible. The cork tiles and cork-composition tUe did not have distinguishable machine

or grain du'ections. Both of their principal

dimensions showed appreciable clmnge.

The dimensional changes of the various

monolithic com])ositIons as a whole were small.

The fiberboards and plywoods showed much

less expansion and contraction in both principal dimensions than the strip-wood floorijigs

in the across-grain direction. Of the stripwood floors, maple showed the greatest change

and edge-grained Douglas fir the least. Among

floor coverings in general, dimensional clianges

of the strip-wood floors in the across-grain

direction were by far the greatest.

In order to prevent a large over-all dimensional change from oecuning in one direction of a room, some floor coverings are installed in

small units, such as tile or unit-block, with the

machine or grain direction of alternate units at

right angles to each other.

Washington, May 1, 1942.

[71

BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page ii] BMS33 Plastic Calking Materials lOfS BMS34 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 1 10^ BMS35 Stability of Sheathing Papers as Determined by Accelerated Aging 10(5 BMS36 Structural Properties of Wood-Frame Wall, Partition, Floor, and Roof Constructions

with "Red Stripe" Lath Sponsored by the Western Paper and Manufacturing Co.. 10^ BMS37 Structural Properties of "Palisade Homes" Constructions for Walls, Partitions, and

Floors Sponsored by Palisade Homes 10^ BMS38 Structural Properties of Two "Dunstone" Wall Constructions Sponsored by the W. E. Dunn Manufacturing Co 10(4 BMS39 Structural Properties of a Wall Construction of "Pfeifer Units" Sponsored by the Wisconsin Units Co lOjJ BMS40 Structural Properties of a Wall Construction of "Knap Concrete Wall Units" Sponsored

by Knap America Inc 100 BMS41 Effect of Heating and Cooling on the Permeability of Masonry Walls 100 BMS42 Structural Properties of Wood-Frame Wall and Partition Constructions with "Celotex"

Insulating Boards Sponsored by the Celotex Corporation 150 BMS43 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 2 100 BMS44 Surface Treatment of Steel Prior to Painting 100 BMS45 Air Infiltration Through Windows 100 BMS46 Structural Properties of "Scot-Bilt" Prefabricated Sheet-Steel Constructions for Walls,

Floors, and Roofs Sponsored by the Globe-Wernicke Co 100 BMS47 Structural Properties of Prefabricated Wood-Frame Constructions for WaUs, Partitions, and Floors Sponsored by American Houses, Inc , — 100 BMS48 Structural Properties of "Precision-Built" Frame Wall and Partition Constructions

Sponsored by the Homasote Co 100 BMS49 Metallic Roofing for Low-Cost House Construction 100 BMS50 Stability of Fiber Building Boards as Determined by Accelerated Aging 100 BMS51 Structural Properties of "Tilecrete Type A" Floor Construction Sponsored by the

Tilecrete Co 100 BMS52 Effect of Ceiling Insulation on Summer Comfort ^ 100 BMS53 Structural Properties of a Masonry Wall Construction of "Munlock Dry Wall Brick"

Sponsored by the Munlock Engineering Co 100 BMS54 Effect of Soot on the Rating of an Oil-Fired Heating Boiler 100 BMS55 Effects of Wetting and Drying on the Permeability of Masonry Walls 100 BMS56 A Survey of Humidities in Residences , 100 BMS57 Roofing in the United States'—Results of a Questionnaire 100 BMS58 Strength of Soft-Soldered Joints in Copper Tubing 100 BMS59 Properties of Adhesives for Floor Coverings 100 BMS60 Strength, Absorption, and Resistance to Laboratory Freezing and Thawing of Building

Bricks Produced in the United States 150 BMS61 Structural Properties of Two Nonreinforced Monolithic Concrete Wall Constructions.. 100 BMS62 Structural Properties of a Precast Joist Concrete Floor Construction Sponsored by the Portland Cement Association 100 BMS63 Moisture Condensation in Building Walls . ^ 100 BMS64 Solar Heating of Various Surfaces 100 BMS65 Methods of Estimating Loads in Plumbing Systems 100 BMS66 Plumbing Manual 200 BMS67 Structural Properties of "Mu-Steel" Prefabricated Sheet-Steel Constructions for Walls,

Partitions, Floors, and Roofs Sponsored by Herman A. Mugler 150 BMS68 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 3 150 BMS69 Stability of Fiber Sheathing Boards as Determined by Accelerated Aging 100 BMS70 Asphalt-Prepared Roll Roofings and Shingles 150 BMS71 Fire Tests of Wood- and Metal-Framed Partitions 200 BMS72 Structural Properties of "Precision-Built, Jr." Prefabricated Wood-Frame Wall Construction Sponsored by the Homasote Co 100 BMS73 Indentation Characteristics of Floor Coverings 100 BMS74 Structural and Heat-Transfer Properties of "U. S. S. Panelbilt" Prefabricated Sheet-Steel Constructions for Walls, Partitions, and Roofs Sponsored by the Tennessee Coal, Iron & Railroad Co 150 BMS75 Survey of Roofing Materials in the North Central States - 150 BMS76 Effect of Outdoor Exposure on the Water Permeability of Masonry Walls 150 BMS77 Properties and Performance of Fiber Tile Boards 100 BMS78 Structural, Heat-Transfer, and Water-Permeability Properties of Five Earth-Wall Constructions . 200 BMS79 Water-Distributing Systems for Buildings 150 BMS80 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 4 150 BMS81 Field Inspectors' Check List for Building Construction (cloth cover ; size, 5 by 7 inches) 200 BMS82 Water Permeability of Walls Built of Masonry Units 200 BMS83 Strength of Sleeve Joints in Copper Tubing Made with Various Lead-Base Solders 100 BMS84 Survey of Roofing Materials in the South Central States 150 BMS85 Dimensional Changes of Floor Coverings with Changes in Relative Humidity and

Temperature . 100