Properties of Cavity Walls

United States Department of Commerce

National Bureau of Standards

Building Materials and Structures Report 136
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UNITED STATES DEPARTMENT OF COMMERCE . Sinclair Weeks, Secretary NATIONAL BUREAU OF STANDARDS . A. V. Astin, Dirrcior

Properties of Cavity Walls

Daniel S. Goalwin

Building Materials and Structures Report 136

Issued May 20, 1953

Fur salelby the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C.

Price 15 cents
Contents Page

1. Introduction 1 2. Cavity-wall design 1

3. Materials 2

4. Construction of walls 4

4.1. Workmanship 4

4.2. Construction details 4

5. Structural properties : 5

5.1. Compressive load 6

5.2. Transverse load 7

5.3. Concentrated load 8

5.4. Impact load 8

5.5. Racking load 9

6. Water permeability 9

6.1. Method of testing 10

6.2. Test results 10

7. Heat transfer 10

7.1. Test equipment and procedure 10

7.2. Test results 11

8. Fire resistance 12

8.1. Test specimens 12

8.2. Test results 13

9. Discussion and summary 14

10. References 15
Properties of Cavity Walls

Daniel S. Goalwin

A compilation is given of data on the performance characteristics of cavity walls, in- cluding previously published and some hitherto unplublished material. Structural tests were conducted on cavity walls of brick, concrete block, and structural clay tile. Other

tests were made on the properties of wall ties, rain penetrability, thermal transniittance, and

fire resistance. Under certain conditions of loading, compressive strength, resistance to concentrated

load, racking load, and impact strength were found to be roughly eciuivalent to those of conventional walls using the same quantity and quality of material. With respect to re- sistence to transver.se load, the cavity walls were somewhat inferior. When properly flashed and with suitable weep holes, the cavity walls had satisfactory resistance to rain penetration.

Their thermal transmittance was about 25 percent lower than for similar solid walls. 'J'heir resistance to the effect of fire was satisfactory provided certain limiting loading conditions were met.

1. Introduction

A cayity wall is a form of masonry \yall construction consisting of tAvo parallel \yythes ^ of

masomy separated by a continuous air space, or

cayity, usually about 2 in. wide. It is a type of

construction that lias been Ayidely used in Great

Britain for many years, and %yhich in recent years

has come into greater use in this covmtry. Cayit}"

walls may be constructed of yarious combinations

and thicknesses of brick, stone, structural clay tile, concrete masonry, concrete, etc. One of the adyantages claimed for the cavit}'-

wall construction is that the air space acts to pre- vent rain or moisture that has seeped through the

outer w^-the from penetrating the inner wythe.

In addition, the cayity interrupts the continuity

of the masonry and provides the additional insulating effect of an ah space. These advantages

may be lost by improper design of cavity waUs,

particularly^ Avith respect to such items as flashings,

openings, ties, and wall intersections, or lack of care in construction.

Common practice at present is to distinguish

between hollow and ca^aty walls. Hollow walls

are walls that contain masonry bonds or bridges;

these may permit the passage of water between the

faces of the walls. In properh* built cavity walls,

there is no masonry bridge permitted, between the

outer and mterior wythes, the tAvo tiers being

bonded by means of metallic or other nonmasonry

ties to maintain a substantialh' constant caA'ity

width. These ties are usualh* rods or Avires bent

into Z or rectangular shapes, aft'ording anchorage

by embedment of the ends in mortar joints.

Water that penetrates the outer leaf of a caAuty

Avail seeps doAA-n its inner face and is diA^erted outAvard by means of flashings, genei-ally placed near

' The terms "wythe" and "leaf" are used interchangeably.

the bottom of the cavity and aboA^e windoAvs and

other openings, alloAvuig the Avater to pass through

weep holes in the outer face. These holes, Avhile necessary to dispose of Avater, should be kept small

so as to exclude rodents and to preA'ent any substantial circulation of air in the cavity, AAdth con- sequent increase in thermal transmittance. Tests of structm-al properties, fu-e resistance,

heat transfer, and Avater resistance of cavity Avails have been made at the National Bureau of Standards; most of these tests have been described in

reports of the Building Materials and Structiu"es

series. It is the purpose of this report to collect both previously published and hitherto luipublished data so as to summarize in one report information on caA'itA^ AvaUs required for building design,

construction, and code proparation.

2. Cavity-Wall Design

Design criteria for caA'ity Avails may be found m

various reference Avorks, including those of Fitzmam-ice, "Principles of Modern Building" [1],- Plummer, "Brick and Tile Engineermg" [2], and

"Tile Engineering" [3]. Design of the Avails tested

foUoAved closely the general requirements for caA^-

itA- Avails of the "American Standard Building Code

Requirements for Masonry"" [4], Avhich is noAV in

the process of revision. Sound engineering practice requhes that the compressiA^e stresses in caA'ity

Avails shaU not exceed those given in table 1. These compressive stresses are based upon the

gross cross-sectional area of tlie wall, mmus the

area of the caA^ty betAveen the AVA-thes, Avith the

assumption that the floor loads bear on but one

of the tAVO Avythes. When such A\-alls are loaded

imiformly at "the center of the Avail, the aUowable

2 Figures in brackets indicate the literature references at the end ot this paper. 1
stresses may be increased by 25 percent. When

anticipated wind pressures exceed 20 Ib/ft^, type

B mortar should not be used on cavity walls of

12-ui. thickness or less. Table 1. Maximum loading for masonry cavity walls

Material

Allowable compressive

stress (on gross less cavity area, load bearing on

only one wythe).

Type A-1 mortar ' Type B

mortar i

Solid masonry units: Strength greater than 2,500 Ib/in.^ Strength 1,500 to 2,500 lb/in.2 ___ Hollow masonry units _

Ib/in.- 140

100

70

IbUn.i 110

80

55

1 The mortar designations used in this paper are similar to those in the

tentative ASTM Specifications for Mortar for Unit Masomy [7]. Mortar

A-1 is defined as consisting of 1 part of Portland cement by volume, J.4 part of hydrated lime or lime putty, and aggregate in amount not less than 2\i nor more than 3 times the sum of the volumes of the cement and lime used. Mortar B consists of 1 part of portland cement by volume, not less than li. nor more than V/i parts of hydrated lime or lime putty, and aggregate in amount

not less than 21.4 nor more than 3 times the sum of the volumes of the cement and lime used. ASTM C270-51T requires that the average wet compressive strength of 2- in. cubes of the mortar at 28 days be not less than 2,500 lb/in.2 for type A-1 and

750 lb/m.2 for type B. Cavity walls should not exceed 35 ft in height,

except that 10-in. cavity walls should not exceed 25

ft in height above their support. As cavitj^-wall

floor loads are usually carried by the inner wythe,

the outer wythe is customarily 4 in. in nominal

thickness, and the thickness of the inner tier is increased if needed for high walls or to support

heavy loads. A nominal 10-in. cavity wall consists of two nominal 4-ui. leaves and a 2-in. cavity ; a nominal 14-in. cavity wall consists of a 4-in. outer leaf, a 2-in. cavity, and an 8-in. inner leaf. The facing and backing of cavity walls should

be bonded with %6-in. -diameter steel rods or metal

ties of equivalent thickness embedded in the

horizontal joints. The ties shall be spaced uniformly to provide at least one per 4?'2 sq ft of wall

surface; the distance between adjacent ties should

not exceed 26 in. Rods bent to rectangular shape

should be used with hollow masonry units laid

with cells vertical; in other walls the ends of the

ties should be bent to 90-degree angles to provide

hooks not less than 2 in. long. Additional bonding

ties should be provided at all openings, spaced not more than 3 ft apart aromid the perimeter and

withia 12 in. of the opening. Ties should be of

corrosion-resistant metal or coated with a cor- rosion-resistant metal or other approved protective

coating.

British specifications [5] require that steel wall

ties be coated with zinc. They also require a

crimp or dip in the ties so as to prevent water

traveling across the tie to the inner wythe. If no

crimp is used, the tie should be inclined downward

to the outer wythe.

Because one of the purposes of the cavity is to provide a barrier against the penetration of moisture,

it is essential to provide flashing wherever the

cavit}' has been bridged for any purpose, such as heads and jambs of openings, joist bearing points,

etc.Proper drainage should be provided at the base

of the cavity to dispose of any water that might

penetrate into the cavity. This may be ac- complished b}^ providing weep holes in the vertical

joints of the course of masonry of the outer tier immediately above a flashing. The cavity must

be kept clear of mortar droppings so that the weep

holes are not obstructed and so that moisture can- not be transmitted across the cavity on a bridging

of mortar.

3. Materials

Tests were conducted at the National Bureau of

Standards BMSlOl [6] on the strength of wall ties under axial, tensile, and compressive load, and on

the corrosion resistance of steel ties coated with

various materials.

Table 2 lists the basic dimensions of some of the

ties, partial results of compressive tests on tie assemblies, and which tie types were used in wall

specimens for other tests described later in this report. Some of the ties are shown in figure

1. Outdoor-weathering specimens are shown in figure 2. The tensile specimens failed by pulling out of

the tie, by tension failure in the tie, or by crushing

of the mortar imder the tie, with subsequent

splitting of the brick-mortar assembly. Partial

bond failure of the tie occurred in many specimens

that failed m tension or by crushing of the mortar,

the ends of the ties often having slipped in the

bed as much as ]i in. The compressive-strength

specimens failed either by buckling of the ties or

Table 2. Properties of typical wall ties

Over-all dimensions Maximum compressive load 1 Kind of material Shape Used in walls Length Width Thickness Mortar A-1

Mort'r B

Copperweld

in. 6in. 6in.

0. 027 Z-shape

lb.

3, 880

2, 025

600

lb.

2, 180 1.810 2E.

Steel 2 6 6 .188 ....do Do.2 6 6 .131 ....do .520 Do.2 6 4 . 158 Rectangular.. 2, 310 2, 060 Do 6 6 . 188 Z-shape .. IC, 2A, 2B, 2C, 2D, 2E, 3A, 3B, 3C, 3D. Do 6 4 .250 Rectangular 1.4, IB, ID, IE.

• Average values were obtained from tests on groups of 5 like specimens. Compressive strengths of mortars: A-1, 4,450 lb/in.-; B, 1,330 Ib/in.^

.

2 Average yield strength of steel wires 86,000 lb/in.=, the average tensile strength 90,000 lb/in.2.

2
by crushing of the mortal- iigainst. tho ends of the

ties.Uncoated steel ties and Ihose coaled with neat cement or mortar were lightly i-iisted in 10 days

or less of indoor (accelerated ) weathering, and

most were severely rusted in liO days, ('ementitious coatings did not retard rust formal if)n and

even appeared to have had an accelerating effect. Coatings of coal-tar paint aflt'orded some protection, but within 120 days the ties were severely

rusted adjacent to the masonry. It is possible

that the coatings at these points were nicked

with the trowel when the mortar protruding from

the joints was cut away. The copper coatings on

the copperweld ties were darkened V)y the exposure, but no evidence of rusting of the steel beneath the copper was noted.

Uncoated steel ties corroded in less time when

exposed to outdoor than to indoor (accelerated)

weathering. The cementitious coatings seemed

to oflFer better protection to the ties when exposed

outdoors than indoors. Ties coated with paint were moderately rusted at points adjacent to the

inner faces of the masonry after 180 days of ex- posure.

Physical properties of the concrete blocks,

brick, and tile used in tests described later in this

report are listed in table 3. Details of the conFiGURE 3. Details of concrete-block and structural clay tile. The above include all test specimens except those used in fire-enduranoe

tests.
Table 3. Physical properties of the masonry units used in the cavity walls

Concrete blocks

Water absorption (24- Density hour cold immersion) Compressive Used in walls Dimensions Dry Aggregate of strength weight

concrete By By volume (gross area) weight of concrete

in. Ibjblock Iblft 3 Percent Ibljt 3 Ibjin.'i lA, IB, IC, ID, parts lE-1, lE-2... 4.0 by 23.8 bv 7.9_._. 22 Cinders ._. 88 14.4 12.7 900 Part lE-1 .__ 4.0 by 23.8 bv 7.9 31 Expanded slag 108 10.2 11.

1

895 Part ]E-2__ _ 4.0 by 23.8 by 7.9 33 Sand and gravel.-. 130 6.5 8.4 860

Brick

Used in walls Dimensions Dry

weight

Water absorption Modulus

of rupture

Compressive

strength 5-hour boil Saturation

coefficient

Initial rate

of absorption -

2A, 2B, 2C, 2D

3A, 3B, 3C, 3D

2E

in. 8.1 by 3.6 by 2.3 8.0 by 3.8 by 2.3 8.0 by 3.6 by 2.2lb/brick 4.1 4.8Percent

18.7 14.7

20.0

0.74

.69

.79

oz

1.5

1.4

Iblin.i 540 830

450

Ib/in.- 3,240 5,160 3,580

Tile

Used in walls Dimensions Dry

weight

Cells per

tile

Thickness of face shell (minimum)

Ratio, width

of cell to thickness of bearing shell

Water

absorption

(1-hr boil)

Compressive

strength

(load applied

to side)

in. lb/tile in. Percent Ib/in.i 3A, 3B, 3D 3.8 by 4.9 by 12.0. _._ 9.5 4 0.4 2 5.9 1.720 4A-1 3.8 by 12.0 by 12.0. . 17.2 • 3 .5 5 10.2 1,040 4A-2 _._ 3.8 by 5.0 by 12.0.. 8.6 2 .5 5 10.7 860

1 24-hr cold -f- 5-hr boil.

2 Gain in weight of dry brick (30 in.2) in contact with }.i in. of water for 1 minute.

Crete block and structural clay tile (except the

tile used for fire-endurance tests) are shown in

figure 3. The blocks were laid with the cells vertical. Only cement-lime mortars were used in the

constructions described in this report. Definitions

of the classes of mortar are taken from the ASTM

Tentative Specifications for Mortar for Unit

Masonry, C270-51T [7], and are given in table 1. Mortar B is the familiar 1:1:6 by volume. The

amount of water added to the mortar was in each

case adjusted to the satisfaction of the mason.

4. Construction of Walls

4.1. Workmanship

The walls tested fall into two general classes with respect to workmanship. Workmanship A

was superior to the commercial workmanship

designated as workmanship B. In workmanship

A, the head or cross joints were filled solidly.

In workmanship B, the mortar w^as applied only

to the outer edges of the head or cross joints.

In both workmanships, a wood strip was placed on the ties to prevent mortar droppings from

fouling the ties or the weep holes. The effect of workmanship on compressive

strength of brick walls other than cavity walls is discussed in "Compressive Strength of Clay

Brick Walls" [8] and on transverse strength and

water permeability in "Watertightness and Transverse Strength of Masonry Walls" [9].

4.2. Construction Details

Four wall types have been tested at the National

Bureau of Standards, concrete-block walls, all- brick walls, walls with brick facing and clay-tile

backing, and walls with structural clay tile for both facing and backing.

Details of construction, including size, mortar,

and workmanship, are given in table 4. A bricktile wall under construction is shown in figure 4.

Figure 4. A brick-tile cavity wall under construction for use in structural tests.
Table 4. Construction details of the test walls

Wall No.

lA.

1B_..

IC--- ID

lE-1. lE-2. 2A.-

2B.__. 2C-... 2D-S.

2D_...

2E.... 3A. 3B.

3C- 3D_

4AType of wall

Cinder-concrete

block. do

do

do

Concrete block do 5

Brick. do

do

Brick (solid)

-

Brickdo

Brick-tile s_

do 9..._

do

do s.-..

Hollow tileType of tests

Compressive, transverse, impact. Racking Water permeability Heat transfer Fire resistance do._ Compressive, transverse, impact. Racking Water permeability Heat transfer do

Fire resistance Compressive,

impact. Racking

transverse,

Water permeability. Heat transfer

Fire resistanceReference

Report

BMS21-

BMS21__

BMS82.-

(3) BMS117. BMS120-

BMS23-.

BMS23-- BMS82-

(') (')

BMS24--. BMS24--.

BMS82.-.

RP37

Wall designation

AX-C, AX-T, AX-I

AX-R_.--

B123 HT-47

12 - 3--- BD-C, BD-T, BD-I BD-R

B169--- HT-23- HT-24

74, 75, 76 AU-C, AU-T, AU-I- AU-R

B124, B271, B272---- None

110, 111

Nominal sizes of walls

Width Height Thickness

ft.

10

10

10

10

10m

10

9'A m

Mortar '

A-1 .

A-1.. A-1

A-1.. B...

B.... B.

B.---

B.... B....

B....

B...-

B....

B..-- B...-

B..--

(0

Workmaii-

.shij) '

A (brick), B

(tile). A (brick), B

(tile), A (brick), B

(tile). A (brick)

(tile).

B.

B

1 Definitions of mortars given in table 1. Mortar B was 1:1:6 by volimie. Mortar A-1 strength at 28 days exceeded 2500 Ib/in.^. Mortar B strength at

28 days exceeded 750 lb/in. 2.

2 Workmanship A was superior, head joints filled. Workmanship B was commercial, head joints buttered at the edges only.

3 From unpublished data.

* This wall was divided into two 8- by 11-ft sections; one section of cinder units, one section of sand and gravel units.

5 This wall was divided into two 8- by 11-ft sections; one section of cinder units, one section of foamed-slag units.

6 Brick facing, tile backing.

' 1;1:4 by volume. Strength at 60 days, 1,065 lb/in.2. The concrete-block walls tested for fire endurance consisted of two 8- by 11-ft sections each,

separated by a %-in. air space, with blocks having

different aggregates in each section. The units

of one section of wall lE-1 contained cinder

aggregates, the other sand and gravel aggregates; one section of wall lE-2 also contained cinder

aggregates, the other foamed-slag aggregates.

For the walls used in the heat-transfer tests, the

edges of the cavity were closed by strips of

lumber and plastered over with mortar.

No finish was applied to the faces of any of the

walls used in the structural or rain-penetrabUity

tests. The concrete-block wall ID tested for thermal transmittance had two coats of portland

cement-base paint on the outside face and three

coats of plaster applied directly over the inside

face of the concrete blocks. The two structural

clay-tile walls, 4A and 4B, tested for fire resistance,

had % in. of gypsum plaster on the exposed face

and 1:3 portland-cement plaster plus 15 percent

of lime on the unexposed face. Ties were placed approximately 24 in. apart on

horizontal centers in alternate bed joints for the

concrete-block walls used in the structural, rain

penetration, and fire-endurance tests, and in every third joint for the cinder-concrete block

wall, ID, used in the heat-transfer tests. They

were placed in every sixth brick course for the

brick and brick-tile walls.

5. Structural Properties

The kinds of loads encountered on exterior

walls and a detailed analysis of engineering

FiGUKE 5. Concrete-block cavity wall under compressiveir load.uui Load was applied through a round steel bar above beam (not visible).

5
principles for the design of small houses are dis- cussed in BMS109 [10]. Three types of cavity walls were subjected to compressive, transverse, concentrated, impact,

and racking loads at the National Bureau of

Standards in accordance with the procedures and

methods outlined in ASTM Standard E72-47T

and given in BMS2 [11]; these tests are described

in detaU in BMS21 [12], BMS23 [13], and BMS24

[14]. At least three wall specimens were included

in each test group. In general, test procedure was to apply the load in increments, recording

the deflection, then release the load and record

the set.

5.1. Compressive Load

With one exception, compressive loads were

applied to a steel plate covering the upper end of

the specimen. The load was applied uniformly

along a line parallel to the inside face and onethird the thickness of the specimen from the

inside face. For one set of tests on a brick cavity

wall, 2 A, the load was applied to one wythe only.

A wall under compressive load is shown in figure 5; data obtained from the compressive-load

tests are listed in table 5 and presented graphically

in figures 6 and 7. Failure of the concrete-block cavity walls oc- curred by crushing of the blocks in the back wythe

in one or more courses near the top of each of the

specimens. Two of the brick cavity walls failed

by crushing of the brick and mortar-bed joints in

two or three courses of the back wythe at about

two-thirds the height, followed by rupture of both

backing and face tiers at this height; one specimen

failed by crushing of a few bricks and a mortar bed

Table 5. Results of structural tests

Figures are averages for three specimens.

Wall types Mcrtar Workmanship '

Compressive tests Transvers" tests (equivalent maxi- mum load)

Impact (maxi- mum height of drop of 60-lb sandbag)

Racking

(maxi- mum

thrust 3)

Racking modulus Distance

load applied from inside

face

Maxi- mum

load

Maxi- mum

stress 2

Cinder-concrete block

walls lA and IB. Brick walls 2A and 2BI

Brick walls 2A_.

1-A._. BB

in.

3. 33

3. 12 0)

3. 25

Ibllin ft

37, 800

62, 100

50, 600

27, 800

Iblin.i 394

650

528

290

'bift ' 49. 8ft

3. 0

IblUn ft

6, 010

5, 660

tbift 2 18.2X10" A 25.3 2.8 12.7 B A

Brick-tile walls 3A

and 3B.

Brick-tile walls 3A

B

B

A-brick; B-tile

A-brick; B-tile

21.5 (inside face)..

_

29.1 (outside face).

3.7 (inside face)

-

3.0 (outside face)

.

5, 160 19.3

1

' Workmanship A, superior. Workmanship B, commercial.

2 On net area, that is, total area less area of cavity.

3 Thrust applied near upper corner.

* Load applied and centered on back wythe only.

DEFLECTION, IN. Figure 6. Wall shortening under compressive loads. Opening circles represent shortenings, closed circles sets after removal of the corresponding load. Wall lA, concrete-block cavity wall; wall 2A, brick cavity wall; wall 3A, brick-tile cavity wall. 6
50,000

40,000

30,000

20,000

10,000

/

/

/

/ /

, /

o-o——

I

/

/

/

/ ,/ WALL lA |WALL 2A /

;

1

/ WALL 2

A

/ LOAD ON

/ BACK WYTHE ONLY

/

/

1 WALL 3A

/

11

/ / 1 /

1 /

1, /

1 / f

1 /

Lio—

<do—

1

c\

I I

LATERAL DEFLECTION, IN. Figure 7. Lateral wall deflections under compressive loads. Open circles represent lateral deflections, closed circles lateral sets after the removal of the corresponding load. Wall lA,

couprete-block cavity wall; wall 2A, brick cavity wall; wall .3A, brick-tile.

joint in the back wythe at about two-thirds the

height. The load at faihu-e of the brick cavity

walls loaded on one wythe only averaged 80 per- cent of the load at failure of the walls loaded on both wythes. Each of the brick-tile cavit3^-wall

specimens failed by breaking of the tile in the upper two or three courses; no failure of the bi-ick facing was observed.

5.2. Transverse Load

Transverse load tests were made with the wall

in a vertical position. Two equal loads were applied, each along horizontal lines at one-quarter

of the span from the supports toward the middle

of the span. The wall rested against a roller near

the top and another near the bottom, separated

by a span of 7 ft 6 in.; the loading rollers were

thus 3 ft 9 in. apart on the loaded wythe.

A wall under transverse load is shown in figure

8. The results of the transverse load tests are presented in table 5 and the lateral deflections in figure 9. Each of the concrete-block cavity walls failed by

rupture of the bond between the blocks and the

mortar in both the face and the back wythes at bed

joints, usually between the loading rollers. In the

brick cavity walls, the bond failure occurred near

a loading roller in both the loaded and opposite

faces. Three of the brick-tile cavity walls failed by rupture of the brick-mortar bond at midheight in the

facing and by rupture of the bond between the

Figure 8. Brick-tile cavity wall under transverse load. Loading rollers at quarter span are shown to the right of the wall.

242501--,')3 2
tile and the mortar at one or two bed joints at or between the loading rollers in the backing. For

three other specimens, the bond between the tile and the mortar ruptured at a bed joint near midheight in the backing, the bond rupture on the

brick face occurring at a bed joint between the

loading rollers in the facing.

5.3. Concentrated Load

A concentrated load was applied through a 1-in. diameter steel disc placed against the face of the

test specimen at what was thought to be the weakest place. A. wall under concentrated load is shown in figure 10. Only one specimen failed below the 1,000-lb load

obtainable with the apparatus used. This was one

of the brick cavity walls on which the load had

been applied at a head joint. Failure of this specimen occurred by rupture of the bond between the

brick and mortar at a bed joint below when a

646-lb load was applied.

5.4. Impact Load

The impact loads were applied by allowing a

60-lb sand bag to swing as a pendulum. The bag

struck the wall about the midpoint between four

wall ties near the center of one face of the speci- men. A wall preparatory to impact is shown in

figure 11. The test results are given in table 5. For the three concrete-block cavity walls, bed

joints near midheight in both the face and back

Figure 10. Brick cavity wall under concentrated ilu iist. "A" indicates the point of application of load through 1-in. disk.

8
Figure 11. Brick-tile cavity ivall preparatory to impact test. Sandbag weighs GO pounds.

wj'thes cracked at drops of 1.5, 2, and 2.5 ft, re- spectively. The tests were continued to failure,

which finally occurred by displacement of the bond

between the blocks and the mortar at those bed

joints that had previously cracked.

For one of the brick cavity walls, a bed joint

cracked near midheight at a drop of 1.5 ft, and

another bed joint in the far wythe cracked at a

2.5-ft drop. A. second specimen also showed a cracked bed joint at 1.5 ft. The tests were continued to failure, which finally occurred by ruptm'e

of the bond between the brick and the mortar at one or more joints on all three specimens.

For the thi-ee brick-tile cavity-wall specimens,

the bond between the tile and the mortar in the

back ^vythe ruptured transversely at or above

midheight at drops of 1.5, 2, and 2 ft, respectively.

The bond between the brick and the mortar in the

facing ruptm'ed transversely at or above the midspan at slighth" higher drops. Both the backing

and the facing finally failed by opening of these

cracks or by the formation of new ones in the tile backing. For two of the specimens, both the back

wythe and the face wythe failed at the same drop.

For one of the specimens, the tile backing failed

fu'st, followed by failure of the brick facing at the next drop.

5.5. Racking Load

The test specimens were 8 by 8 ft, twice as large

as any of the other walls for structm'al tests, and

were braced on the lower corner to prevent horizontal sliding when thrust was applied. The

loaded end was constrained from vertical movement b}^ tie plates, but was allowed to move horizontally by a series of plates and rollers under the

tie plates. The thrust was applied horizontally

at the upper corner of the specimen and the

Concrete-block cavity wall under racking load.

Ties at top restrict vertical motion. Compressometers measm-e horizontal derormation.

horizontal displacement relative to the fixed base

measm'ed at the other end of the wall (fig. 12).

Test results are given in table 5. The racking modulus given in table 5 is "the

force causing a racking deformation of one foot

for a wall one foot square, computed from the

initial rate of deformation," reference [10]. T^-pical values of the racking modulus ma}' be found

in table 15 of reference [10]. One of the concrete-block walls failed b}' crushing of blocks in both the facing and the backing at the loaded corner. The other two failed by ruptm'e of the blocks of both the face and back wythes

approxiniateh' along a diagonal between the

pouit of application of the load and the stop.

Two of the brick walls failed by rupture of both

facing and backing along a diagonal between the

point of application of load and the stop. The

com-se of the cracks followed the joints in some

places and passed du'ectly through the brick in

others. The third specimen faded b}' ruptm-e of

the back wj-the only.

The tile wythe of each of the brick-tUe waUs

faUed by ruptm-e between the masomy imits and

the mortar in the bed and head joints along a diagonal from the load to the stop. On only one

of these walls did the brick facing faU.

6. Water Permeability

Because exterior masonry walls of houses oi other buildings ma}' be penetrated hy ^vind-driven

rains, with subsequent damage to the interior

finish of such structm-es, the water permeability

9
To air //ne Figure 13. Water-permeahility test chamber.

of one brick, three brick-tile, and one concrete- block cavity wall was examined and is reported

in BMS82 [15].

6.1. Method of Testing

The test apparatus is shown in figure 13. The

wall specimens were clamped into position against

sponge-rubber gaskets so that the exposed face

formed one side of a pressure chamber. Water

from a perforated pipe was applied to the upper

portion of the exposed face (inside the chamber),

the 40-gal/hr rate being sufficient to cover the

wall face with a thm sheet of flowing water. The

applied air pressure maintained in the chamber was equal to that produced by a 2-in. head of

water (approximately 10 lb/ft about the maximum pressure difference on two faces of a wall

that might be caused by a 60-mph wind.

The air temperature in the testing I'oom varied

between 50° and 75° F. The walls were tested

for not less than 1 day. As the backs of the walls

had been painted with whitewash, the discoloration produced by moisture (dampness) on the back

could be easily detected. The permeability test was more severe and of greater duration than the

natural wind and rain storms to which most

building walls are ordinarily subjected.

6.2. Test Results

With the exception of wall IC, table 4, the backs

of the walls remained dry during 1-day tests. Wall IC became wet on the back above the flash- ing in 12 min.

The cavities in one of the brick-tile walls, 3C, was filled with 0.7 lb/ft- of shredded redwood bark;

this wall was tested both before and after the

cavity was filled. With the cavity open, some

moisture appeared in the region around its re- versed flashings in 10 hr, but in the retest, with

the cavity filled, a large damp ai'ea appeared on

the back in 0.2 hr. After the tests, when the back- ! ing wythes were removed, the shredded redwood

bark remained standing; water was visible at only

a few points on the back of the filling, but the i inside of the brick wythe was dripping wet. The j filling contained about 14 percent of moisture by | weight before it was placed in the wall. After the ! tests, it contained 50 percent of moisture at the i bottom and about 20 percent at the top of the ! wall. i According to the Armour Research Foundation j and the Structural Clay Products Institute [16], a ! cavity wall filled with a specially designed pouring j type of fiberglas, but having no wall ties, was i tested and reported to have resisted moisture penetration through the back wythe for a period of

several days. Apparently there was no differen- 1 tial air pressure across the cavity in these tests.

7. Heat Transfer

In order to determine the thermal insulating 1 value of a cavity wall as compared to that of a :| solid wall, and to ascertain to what degree the

ventilation of a cavity wall with outdoor air affects ; its insulating value, heat-transfer tests were made

by H. E. Robinson of the Bureau's staff on brick, j brick-tile, and concrete-block cavity walls. A ij solid brick wall was tested for comparison purposes.

7.1. Test Equipment and Procedure j In the guarded hot-box heat-transfer apparatus ; (fig. 14), heat flowed through the specimen from

the electrically heated metering and guard boxes j to the cold box, which was cooled by a refrigerating l machine. The guard box was used so that the jj space surrounding the metering box could be main- j tained at substantially the same temperature as t the interior of the metering box. This minimized i heat exchange to or from the metering box except [ through the specimen. To keep heat exchange i through the edges of the specim.en to a minimum, \ the top and sides were encased by an insulated

wooden enclosure (not shown in fig. 14). ; For testing, the specimen was placed in the apparatus, the temperature in the cold box adjusted

to approximately 0° F and that in the metering

and guard boxes to 70° F. Air was circulated at approximately 35° F through the enclosure along

the edges of the specimen. After a state of steady

heat flow was attained, the heat transmittance of , the specimen, indicated by the rate at which electric energy was supplied to the metering box, was

observed

.

In order to determine the effect of ventilation of

the cavity on the heat-transfer properties of the

brick and. brick-tile cavity walls, six bricks were

left out of the outside wythe, three at the third and

three at the thirty-second courses, leaving openings into the cavity near both the iDottom and the

top of the wall. In one series of tests on the brick

10
Figure 14. Test apparatus for heat-transfer measurements. To minimize heat exchange through the edges, the top and sides of the spec- imen were encased in an insulated wooden enclosure not shown in this drawing.

wall 2D, the openings in the outside face were

closed with brick chinked with sponge rubber,

thereby completely sealing the cavity. In another

series of tests (see table 6), the openings in the

outside face were partly closed with brick and

sponge rubber. Openings of 4.2-in.^ area, or 1.0

in.^ per linear foot of wall, were left at both top and

bottom. In a further series of tests, the openings

amounted to 7.2 in.^ in area, or 1.7 in.^ per linear

foot of wall, and 89.0 in.^, or 21.0 in.^ per linear

foot, respectively.

Three series of tests were run on brick-tile cavity

wall 3D, with the cavity completely sealed, with

the openings between the bricks of 0.9 in.^ per

linear horizontal foot at both the top and bottom,

and with openings totaling 2.5 in.^ per linear foot

at both top and bottom.

The cavity of the concrete-block wall, ID, was

not ventilated.

7.2. Test Results

The results of the tests on both V(;ntilated and

unventilated walls are given in table 6. In this

table, the heat-transfer coefficients of the speci- mens are expressed in thr'ee ways. The ol)S(!rved

thermal transmittance, u, is the number of Btu

per hour transmitted through each square foot of

the warm face of the specimen for eacli degree F

difference in temperature of the air on tlie two

sides of the wall, with air moving at a velo(;ity of

about 2 mph parallel to the faces on both sides of

the wall. The coefficient u includes the effect of

the warm-surface film coefficient /< and the coldsurface film coefficient /o, the values of which for the test conditions are presented in table 6. The

film coefficients are expressed in Btu per hour per

square foot of surface for each degree F difference

in temperature between the surface and the aii*. The thermal conductance, C, of each of the

specimens is also presented, representing the number of Btu per hour transmitted through each

square foot of the warm face of the specimen for each degree F difference in temperatm-e of the

two faces of the wall.

It is customary to express the heat-transfer

coefficient of a building wall in terms of a selected

thermal transmittance, U, corresponding to conditions of still air on the warm side and air moving

at a velocity of 15 mph on the cold side of the

wall. For these conditions, a value of 1.65 Btu/

(hr)(ft^)(°F) is taken for the warm-surface film

coefficient, fi, and 6.00 for the cold-sm-face film

coefficient, /o. Values of U, calculated from the

test results, are presented in the table for each of

the unventilated walls. When walls 2D and 3D were tested with their

cavities ventilated, the sj^mbols u, U, C, and /<, were not applicable to the results as they are in ordinary cases because part of the heat was carried

away by the ventilating air passing through the

cavity. The quantity u as recorded in table 6 was in each of these cases, therefore, the observed

heat flow through the area of the specimen covered

by the metering box, in Btu per horn* for each

Table 6. Heat-transfer data

Concreteblock wall Solid Brick wall 2D Brick-tile wall 3D

ID

(cavity unventilated)

brick wall 2D-S Cavity unventilated Cavity ventilated Cavity unventilated Cavity ventilated

Openings for cavity ventilation at top and bottom of wall (in.2/lin. ft of wall) 0 1.0 1. 7 21.0 0 0. 90 2.0

Vertical distance between openings.- (ft)-- 7.2 7.2 7.2 6.8 6.8 Observed thermal transmittance, u, Btu/(hr) (ft^) (°F) Corrected thermal transmittance, U Btu/(hr) (ft^; (°F) \. Thermal conductance, C, Btu/(hr) (ft^) (°F) a

"'o.'25

"

.27

.35

0. 44 .53

.89

.31 .35 .48.33

.51

.34

.53

.45

.69

.28

.31

.41

.28

"."42

.30

.43 Warm surface film conductance,/,-, Btu/(hr) (ft^) (°F)... Cold surface film conductance, /o, Btu/(hr) (ft2) (°F) Estimated proportion of heat carried out by ventilating

air

_

(percent)-

1.97

1.51 1.85 1.64

1.95

1.64

1.96

13

1.89

19

.6

1.94

63

2. 04

1.46

2. 07 2.04

17 Estimated rate of ventilating air flow through cavity,

(ft3/min)/lin. ft of wall .4 3.

1

.2 .6

' Between the air on the two sides of the wall, observed under test conditions.

2 Between the air on the two sides of the wall, corrected for a 15-mph wind outside, and still air inside.

3 Between the outer surface of the outer wythe and the inner surface of the inner wythe. 11
square foot and for each degree-F difference in temperature of the air on the two sides of the wall. Solid coiinterparts of the brick-tile and the

plastered concrete-block cavity walls were not

tested, but it is estimated that their u values

would have been about 0.38 and 0.34 Btu/(hr)

(ft^)(°F), respectively, and their U values about

0.44 and 0.38 Btu/(hr)(ft2)(°F), respectively.

As would be expected, the measured u values

of the unventilated cavity walls were considerably

lower than those for their solid counterparts. The

differences obtained in the u values of the solid

and sealed-cavity coimterparts were due to the

insulating effect of the cavity air space, the aver- age thermal conductance of which was approximately 1 .0 Btu/(hr) (ft^) (°F)

.

The u values of the ventilated cavity walls in- creased as the size of the ventilating openings was made larger. Estimated rates of ventilating air flow through the cavity and estimates of the

percentage of the heat entering the cavity that was carried out by the ventilating air are presented

in table 6. The u values of the brick and the

brick-tile cavity walls were increased very little by

the ventilation resulting from openings at top and

bottom of approximately 1.0 in.^ per linear foot

of wall. 8. Fire Resistance

Seven cavity walls were subjected to standard

fire exposure according to American Standards

Association Specification No. A2-1934 and the

American Society for Testing Materials Specification El 19-47, which require that a fire exposure

with standard time-temperature relation^ shall be

applied to the wall. The specifications require

that the wall must carry a continuously applied

load sufficient to cause the maximum allowable

working stress. The first of the following criteria to occur defines failure: (1) An average temperature rise of 250 deg F or a maximum rise of 325

3 The standard furnace temperatures are: 1,000° F at 5 min; 1,300'' F at 10 min; 1,550° F at 30 min; 1,700° F at 1 hr; 1,850° F at 2 hr; 2,000° F at 4 hr;

2,300° F at 8 hr.

deg F measured with thermocouples under asbestos pads on the unexposed side of the wall, (2) the

passage of heat, gases, or flame through the specimen intense enough to ignite cotton waste, or (3)

structural failure. The walls were contained within frames that were moved into place to form one side of the

furnace chamber. They were restrained within

the panel frame with a constant compressive load

applied vertically. One wall was tested fully re- strained. None of the cavities was ventilated.

8.1. Test Specimens

Two of the seven walls tested were of concrete

block, three of brick, and two of structural clay

tile. Construction details are given in table 4,

curing and loading details in table 7. A concrete block cavity wall in position for test is shown in

figure 15. In general, a plate covering both wythes served

to distribute the loads, which were applied uniformly along a line parallel to the faces of the

walls. Walls lE-1 and lE-2 of hollow masonry

units were loaded centrally, lE-1 to 80 lb/in. ^ of gross area, corresponding to 100 Ib/in.^ of gross

less cavity area, and lE-2 to 80 lb/in. ^ of gross

less cavity area. The mortar of wall lE-1 as

tested in cubes averaged 1,403 Ib/in.^, that of wall

lE-2, 2,560 lb/in.2 (both 1:1:6 by volume). These

walls were described in BMS117 [17] and BMS120

[18]. The brick walls were laid in winter, and

the brick were dampened only slightly. As dis- closed by examination after the tests, the mortar

bond was considered good.

Wall 2E-1 was loaded centrally to 236,250 lb, or 125 lb/in. ^, of gross area, corresponding to 156

Ib/in.^ of gross area less cavity area. The load on

wall 2E-2 was 72,000 lb, applied 1% in. off center toward the side exposed to the fire, corresponding

to an average load of 80 lb/in. ^ on the exposed

wythe and 28 lb/in. ^ on the unexposed wythe.

This load is representative of the actual load that

Table 7. Summary of fire-test data

Workmanship commercial, that is, head or cross joints not solidly filled

Wall Material Mortar

(by volume) Curing

Loading

Exposed

wythe

Unexposed wythe

Eccentricity

Fire

intensity

Failure

Type Time

Maximum

deflection

1E-1_

lE-2. Concrete blocli L

do 1

2E-1.

2E-2_

2E-3.

4A-1-

4A-2.

Brick,.

-.._do. do. Hollow tile do 4

1:1:6 (B)

1:1:6 (B)

1:1:6 (B)

1:1:6 (B)

1:1:6 (B)

1:1:4

1:1:4

Days

32

30

33

41

3434

lb/in.

2

100

15680

(»)

125

125

10080

15628

25

25

0

15i

(')

2

2

Percent

101.2

100

101 100 100

Load Avg temp rise.

Load Avg temp rise. dodo

do

hr min

1 16

2 3 45

2 4 43

1 16

5 15

4 55

4 7

4 6

3.4

1. 1 2.4

3.4

3.4 4.2

1.

1

1. 2

1 The concrete-block walls were each divided into two separate 8- by U-ft sections. Wall lE-1 had one section of cinder aggregate and one section of sandand-gravel aggregate.

2 First line refers to section of wall with cinder aggregate; second line to section of wall with foamed-slag aggregate.

3 Restrained from expansion in the plane of the frame.

< Fire clay and gypsum plaster on exposed side; 1:3 cement plus 15 percent of lime on unexposed side. 4A-1 end construction; 4A-2 side construction. 12
Figure 15. Concrete-masonry cavity wall in poaition for

fire test. One 8- by 11-ft section consisted of cinder-concrete units, the other of sand and gravel-concrete units

would bo applied to aiij^exterior wall under the

limitations of some buildin<^ (-odes.

Wall 2E-.'5 was tested restraiiuid within panel

frames made of 2()-in. 120-lb f^irder beams under

conditions representative of installat ion within t lic framework of fire-resistive l)uidlings.

Gypsum plaster was applied to tlu; exi)osefl

sides of tbe structural clay-tih^ walls, 4A-1 and

4A-2, 1:3 cement plus 15 percent of lime on the

unexposed side. The load on tliese walls was

applied 2 in. from the center toward tlu^ exposed

face and resulted in an average load of 125 Ib/in.^ on the exposed wythes and 25 lb/in. ^ on the unex- posed wythes. These walls are described in "Fire

Resistance of Hollow Load-Bearing Walls" [19].

8.2 Test Results

The time and type of failure of the walls and

maximum deflection at failure are listed in table

7. Figure 16 gives time-temperature curves for one of the brick walls, 2E-2. Two of the walls

collapsed under load after approximately 1% hr

of fire exposure; all the others withstood the fire and failed by the temperature-rise criterion at times of 3% hr or more. The temperatures on

the exposed faces of all the walls were similar at corresponding phases of the tests. The walls

which failed structurally, lE-1 and 2E-1, showed

much larger deflections than the others; for in-

'^O I 2 3 4 5 TIME IN HOURS Figure 16. Time-temperature curves for a brick cavity wall

F, Furnace temperatures; I, temperatures in the cavity; P, unexposed-surface temperatures. 13
stance, the maximum deflection of wall lE-1 at

1 hr 10 min was 3.4 in. compared to a maximum

deflection of wall lE-2 at 4 hr 40 min of only 2.4 min.

WaU lE-1 was loaded centrall.y to 100 Ib/in.^

of gross area less cavity area ; the maximum allowable compressive load for this type of construction

loaded centrally is given in reference [4], subsequently developed, as 63 lb/in. ^, and in the tentative revision (table 1, footnote) as 69 lb/in. ^. Wall lE-1 also used a weaker mortar than wall

lE-2.

Wall 2E-1 was loaded centrally to 156 Ib/in.^ of gross area less cavity area ; the maximum allowable

compressive load for this type of construction

loaded centrally is given in reference [4] as 125

lb/in. ^ and in the tentative revision (table 1, footnote) as 100 Ib/in.^. The distance from the center point of the wall

at midheight and the line of application of load

becomes smaller as bowing takes place during fire exposure only when the load is applied eccentrically toward the exposed (back) wythe; this type

of loading thus tends to be more stable than

central, or uniformly distributed, loading. For

example, for a centrally loaded wall and a 3 -in. bow, the line of loading would be about 2 in. from

the outside face of the outer wythe at the midheight of the wall. Because the most severe exposure is on the inside of a structure, and as cavity walls are used predominantly as exterior

walls, eccentric loading toward the exposed face

is not only favorable to a longer fire endurance

but also represents the usual application.

In none of the tests did the temperature in the

cavity become high enough to cause failure of the

metal ties. Although these cavity walls were

tested unventilated, experience with fire-endurance

tests of walls with large cracks indicates that the

fire endurance would not be materially affected by

weep holes. As supplemental information, the fire resistance

for some unventilated cavity walls with and

without plaster and with and without combustible

members framed into the wall are presented in

table 8. Table 8 is adapted from National Bureau of

Standards Building Materials and Structures

Report BMS92 [20]. The fire-resistance ratings

apply where the mortar mixes are not leaner than,

1:1:6 for brick and concrete blocks, and not leaner

than 1:1:4 for structural clay tile. Loads are assumed to be applied eccentrically. Ratings were generally rounded off to a period just shorter

than the test results; some of the ratings were

obtained by S. H. Ingberg by interpolating or extrapolating actual test data. The effects of plaster were derived from test results and accepted

formulas. The thicknesses for which endurance

ratings are given are those most likely to be found

in building construction. Ratings for plastered

brick and concrete-block walls are for ji-in. plaster

thickness and for structural clay tile are for thickness inside and %-in. portland-cement stucco

outside.

9. Discussion and Summary

No failure of the ties was observed in the structural tests listed in table 4. However, tests on

wall-tie assemblies, described in BMSlOl [6], indicated the importance of the mortar in determining the type of the failure and under what

conditions it would occur. Thus, for 1,000-lb/in.^

mortar, a typical assembly tested in compression

failed by buckling of the ties; for 270-lb/in.^

mortar, specimens failed by crushing of the mortar

against the ends of the ties. Assuming a tie spacing of one per 4)^ ft^ of wall area, any of the 6-, 8-, or 10-gage steel or copperweld Z -shaped or rectangular ties provided

adequate bonding between the two wythes to maintain the relative positions of the wythes

against the usual lateral loads to which such walls

may be subjected. Ties in cavity walls are in- tended to connect the two tiers and to serve as

Table 8. Estimated fire resistance of cavity walls

Interpolated results taken from BMS92. All the walls have 2-in. wide cavities; all are loading-bearing. Where plaster is indicated, it is assumed to be not less than yi-'m. of 1 :3 sanded gypsum plaster. For the tile, ?4 in. of plaster or stucco outside and ^/i in. of plaster inside were applied

Nominal

wall thickness

Description

Proportion of cored

spaces in units No plaster

Fire-resistance period

Incombustible members framed

into wall or no framed-in members

Plaster on

one side ^ Plaster on two sides

Combustible members

framed into wall

No plaster Plaster on

exposed

side

10

10

10

10

Clay or shale brick Structural clay or shale tile QH-in. tile) Cored concrete-masonry units (expanded slag or pumice aggregates) Cored concrete-masonry units (expanded burned clay

or shale, crushed limestone, air-cooled slag, or cin- ders) Cored concrete-masonry units i (calcareous sand and

gravel)

Percent

0

60

38

4

3>,2

38

hr

74

hr

2 hr

2\<i

21%

' Coarse aggregate, 60 percent or more calcite and dolomite. ' No plaster on fare-exposed side. 14
struts or tension members between them. Wall

ties of the types tested did not have sufficient

flexural rigidity to transmit shearing forces across

the cavity. Consequently, when one wythe was

subjected to a vertical load, only a small part of

the load was transmitted to the other, and the

two tiers did not exert common action under such

loading.

Exact comparison between the structural tests on cavity walls and similar tests on^ solid walls or

walls with continuous masonry bridges [8, 21] was not possible because of the difficulty of

adequately reproducing mortar and workmanship

and, for some of the tests, conditions of curing.

For most of the compressive-strength tests, too, the distribution of the load over both wythes was

not completely typical of conditions to be met in

service. Rough generalizations that could be

made by comparing these test results, however,

lead to the conclusion that for compressive loads

with both wythes loaded, for concentrated loads,

for racking loads, and for impact loads, the per- formance of the cavity walls was approximately

equivalent to that of walls without cavities, using

the same type and quantity of material; for transverse loads the performance was inferior to that of conventional walls for similar materials

and workmanship. The tests indicated that

cavity walls built according to accepted specifications [4] and having adequate workmanship will withstand reasonable impact and the usual floor and roof loadings of a two-story dwelling.

Results of tests indicate that while the outer

wythe may be highly permeable to wind-driven

' rain, the proper inclusion of flashing and weep

I holes gives adequate protection against leakage

I througli the inner wythe. When highly permeable

j concrete-masoniy units were used in the facing

! wythe, it was necessary to apply a protective

coating, consisting of portland-cement paint, to the exterior surface. The thermal-insulating properties of a cavity

wall depended upon the construction, air permeability, ventilation allowed, etc. In general, an improvement of over 25 percent in insulating

properties was found for unventilated cavity walls

com.pared with solid walls of the same material.

A small amount of ventilation, not exceeding 1 in.^ of opening at the top and bottom, per linear foot

of wall, did not materially increase the thermal

transmittance of the walls. The &-e resistance of unventilated cavity walls was not much different from that of walls having

the same quantity of solid materials except for the load-bearing ability. In the fire tests of those

1^ walls on which the loads applied were within the

I limits given in "Tile Engineering" [3] and table 1

': of this report, structural failure was not observed

before failure by rise of temperature on the unexI posed face. The condition of loading favorable

" to structural stability during fire occuired when

the load was applied eccentrically toward the

exposed (inner) wythe, a condition that would

occur in most applications.

i.

Acknowledgment is made my associates on tlu; staff of the Biiilding Technology Division for their

helpful advi(^e in the preparation of this |)apci' and

especially H. E. Robinson and S. If. Ingbcjg foi- the use of hitherto unpublished data.

10. References

[1] R. Fitzmauricc, Principles of inodcrn V)iiildinf;, I chap. Ill, p. 1.59-172 (1939). Iliis Majesty's Sta- tionery Office, London.

[2] H. C. Pluniiner, Brick and tile engineering (19.50), Structural Clay Products Institute, Washington,

D. C.

[3] H. C. Plummer, Tile engineering (1946), Structural Clay Products Institute, Washington, t). C.

[4] American Standard Building Code Requireinenis for Masonry (A41. 1-1944). (Tentative revision, 19,52.)

[5] Metal wall ties, British Standard 1243:1945, British Standards Institution, London, p]ngland.

[6] C. C. Fishburn, Strength and resistance to corrosion

of ties for cavity walls, NBS Building Materials and Structures Report BMSlOl (1943).

[7] Tentative specifications for mortar for unit masonry, ASTM Designation C270-51T, American Society

for Testing Materials, Philadelphia, Pa.

[8] A. H. Stang, D. E. Parsons, and J. W. McBurney,

Compressive strength of clay brick walls, BS J. Research 3, 507 (1929) RP108.

[9] D. E. Parsons, Watertightness and transverse strength

of masonry walls (1939), Structural Clay Products

Institute, Washington, D. C.

[10] H. L. Whittemore, J. B. Cotter, A. H. Stang, and

V. B. Phelan, Strength of houses, NBS Building

Materials and Structures Report BMS109 (1948).

[11] H. L. Whittemore and A. H. Stang, Methods of de- termining the structural properties of low-cost house constructions, NBS Building Materials and

Structures Report BMS2 (1938).

[12] H. L. Whittemore, A. H. Stang, and D. E. Parsons,

Structural properties of a concrete-block cavity

wall, NBS Building Materials and Structures Report BMS21 (1939).

[13] H. L. Whittemore, A. H. Stang, and D. E. Parsons, Structural properties of a brick cavity-wall construction, NBS Building Materials and Structures Report BAIS23 (1939).

[14] H. L. Whittemore, A. H. Stang, and C. C. Fishburn,

Structural properties of a reinforced-brick wall construction and a brick-tile cavity-wall construction,

NBS Building Materials and Structures Report

BMS24 (1939).

[15] C. C. Fishburn, Water permeability of walls built of masonry units, NBS Building Materials and

Structures Report BMS82 (1942).

[16] Insulated cavity wall. Technical notes of the Structural Clav Products Institute 2 (Mav 1951).

[17] H. D. Foster, E. R. Pinkston, and S. H. Ingberg, Fire

resistance of walls of lightweight-aggregate concrete masonrv units, NBS Building Materials and Structures Report BMS117 (1950).

[18] H. D. Foster, E. R. Pinkston, and S. H. Ingberg, Fire

resistance of walls of gravel-aggregate concrete masonry imits, NBS Building Materials and Structures Report BMS120 (1951).

[19] S. H. Ingberg and H. D. Foster, Fire resistance of hollow load-bearing walls, BS J. Research 2 (1929)

RP37.

[20] Fire-resistance classifications of building constructions, NBS Building Materials and Structures Report BMS92 (1942).

[21] H. L. Whittemore, A. H. Stang, and D. E. Parsons,

Structural properties of six masonry wall constructions, NBS Building Materials and Structvu-es Report BMS5 (1938). Washington, December 4, 1952.

O 15
i


BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page ii] BMS39 Structural Properties of a Wall Construction of "Pfeifer Units" Sponsored by the Wisconsin Units Co 10)5 BMS43 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 2 * BMS44 Surface Treatment of Steel Prior to Painting * BMS47 Structural Properties of Prefabricated Wood-Frame Constructions for Walls, Partitions, and Floors Sponsored by American Houses, Inc 20f5 BMS48 Structural Properties of "Precision-Built" Frame Wall and Partition Constructions

Sponsored by the Homasote Co 15^ BMS50 StabiUty of Fiber Building Boards as Determined by Accelerated Aging * BMS51 Structural Properties of "Tilecrete Type A" Floor Construction Sponsored by the

Tilecrete Co 10^ BMS52 Effect of Ceiling Insulation Upon Summer Comfort 150 BMS53 Structural Properties of a Masonry Wall Construction of "Munlock Dry Wall Brick"

Sponsored by the Munlock Engineering Co lOjS BMS54 Effect of Soot on the Rating of an Oil-Fired Heating Boiler 10^ BMS55 Effects of Wetting and Drying on the Permeability of Masonry Walls * BMS58 Strength of Soft-Soldered Joints in Copper Tubing 100 BMS60 Strength, Absorption, and Resistance to Laboratory Freezing and Thawing of Building

Bricks Produced in the United States 300 BMS62 Structural Properties of a Precast Joist Concrete Floor Construction Sponsored by the Portland Cement Association 150 BMS63 Moisture Condensation in Building Walls 150 BMS65 Methods of Estimating Loads in Plumbing Systems 150 BMS66 Plumbing Manual 350 BMS67 Structural Properties of "Mu-Steel" Prefabricated Sheet-Steel Constructions for Walls,

Partitions, Floors, and Roof, Sponsored by Herman A. Mugler 150 BMS68 Performance Test for Floor Coverings for Use in Low-Cost Housing: Part 3 200 BMS69 Stabilitv of Fiber Sheathing Boards as Determined by Accelerated Aging 100 BMS70 Asphalt-Prepared Roll Roofings and Shingles 200 BMS71 Fire Tests of Wood- and Metal-Framed Partitions * 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 SheetSteel Constructions for Walls, Partitions, and Roofs Sponsored by the Tennessee

Coal, Iron & Railroad Co 200 BMS76 Effect of Outdoor Exposure on the Water Permeability of Masonry Walls * BMS77 Properties and Performance of Fiber Tile Boards * BMS78 Structural, Heat-Transfer, and Water-Permeability Properties of Five Earth-Wall

Constructions 250 BMS79 Water-Distributing Systems for Buildings 200 BMS80 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 4 150 BMS81 Field Inspectors' Check List for Building Constructions (cloth cover, 5x7% inches) 300 BMS82 Water Permeability of Walls Built of Masonry Units 250 BMS83 Strength of Sleeve Joints in Copper Tubing Made With Various Lead-Base Solders 150 BMS84 Survey of Roofing Materials in the South Central States 150 BMS85 Dimensional Changes of Floor Coverings With Changes in Relative Humidity and

Temperature * BMS86 Structural, Heat-Transfer, and Water-Permeability Properties of "Speedbrik" Wall

Construction Sponsored by the General Shale Products Corporation 150 BMS87 A Method for Developing Specifications for Building Construction—Report of Subcommittee on Specifications of the Central Housing Committee on Research,

Design, and Construction 200 BMS88 Recommended Building Code Requirements for New Dwelling Construction With

Special Reference to War Housing * BMS89 Structural Properties of "Precision-Built, Jr." (Second Construction) Prefabricated

Wood-Frame Wall Construction Sponsored by the Homasote Co 150 BMS90 Structural Properties of "PHC" Prefabricated Wood-Frame Constructions for Walls,

Floors, and Roofs Sponsored by the PHC Housing Corporation 150 BMS91 A Glossary of Housing Terms * BMS92 Fire-Resistance Classifications of Building Constructions 300 BMS93 Accumulation of Moisture in Walls of Frame Construction During Winter Exposure.- * BMS94 Water Permeability and Weathering Resistance of Stucco-Faced, Gunite-Faced, and

"Knap Concrete-Unit" Walls 150 BMS95 Tests of Cement-Water Paints and Other Waterproofings for Unit-Masonry Walls 250 BMS96 Properties of a Porous Concrete of Cement and Uniform-Sized Gravel 100 BMS97 Experimental Dry-Wall Construction With Fiber Insulating Board * BMS98 Physical Properties of Terrazzo Aggregates * BMS99 Structural and Heat-Transfer Properties of "Multiple Box-Girder Plywood Panels" for Walls, Floors, and Roofs 150 BMSlOO Relative Slipperiness of Floor and Deck Surfaces 100

•Out of print.

[List continued on cover page iv]
BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page iii] BMSlOl Strength and Resistance to Corrosion of Ties for Cavity Walls * BMS102 Painting Steel 100 BMS103 Measurements of Heat Losses From Slab Floors 15^ BMS104 Structural Properties of Prefabricated Plywood Lightweight Constructions for Walls,

Partitions, Floors, and Roofs Sponsored by the Douglas Fir Plywood Association. . * BMS105 Paint Manual with particular reference to Federal Specifications $1. 25 BMS106 Laboratory Observations of Condensation in Wall Specimens lOfi BMS107 Building Code Requirements for New Dwelling Construction * BMS108 Temperature Distribution in a Test Bungalow With Various Heating Devices 150 BMS109 Strength of Houses: Application of Engineering Principles to Structural Design $1. 50

BMSllO Paints for Exterior Masonry Walls 150 B MSI 11 Performance of a Coal-Fired Boiler Converted to Oil 150 BMSI 12 Properties of Some Lightweight-Aggregate Concretes With and Without an Air- entraining Admixture 100 BMS113 Fire Resistance of Structural Clay Tile Partitions 150 BMS114 Temperature in a Test Bungalow With Some Radiant and Jacketed Space Heaters 250 BMSI 15 A Study of a Baseboard Convector Heating System in a Test Bungalow 200 BMSI 16 Preparation and Revision of Building Codes 150 BMSI 17 Fire Resistance of Walls of Lightweight Aggregate Concrete Masonry Units 200 BMS118 Stack Venting of Plumbing Fixtures _ 150 BMS119 Wet Venting of Plumbing Fixtures 200 BMS120 Fire Resistance of Walls of Gravel-Aggregate Concrete Masonry Units 150 BMS121 Investigation of Failures of White-Coat Plasters __ 250 BMS122 Physical Properties of Some Samples of Asbestos-Cement Siding 150 BMS123 Fire-Tests of Wood-Framed Walls and Partitions With Asbestos-Cement Facings 160 BMS124 Fire Tests of Steel Columns Protected With SiUceous Aggregate Concrete 150 B MS125 Stone Exposure Test Wall _ __. 300

BMS126 The Self-Siphonage of Fixture Traps 200 BMS127 Effect of Aging on the Soundness of Regularly Hydrated Dolomitic Lime Putties 150 BMS128 Atmospheric Exposure Tests of Nailed Sheet Metal Building Materials 200 BMS129 Fire Endurance of Shutters for Moving-Stairway Openings 100 BMS130 Methods and Equipment for Testing Printed-Enamel Felt-Base Floor Covering 150 BMS131 Fire Tests of Gunite Slabs and Partitions 150 BMS132 Capacities of Plumbing Stacks in Buildings 200 BMS133 Live Loads on Floors in Buildings 200 BMS134 Fire Resistance of Concrete Floors 150 BMS135 Fire Tests of Steel Columns Encased With Gypsum Lath and Plaster.. 150 BMS136 Properties of Cavity Walls 150

•Out ot print.