RESEARCH AND DEVELOPMENT BULLETIN RD066

Sound Transmission Loss Through Concrete and

Concrete Masonry Walls

by Albert Litvin and Harold W. Belliston

Rcpnnlrd wth perrmsston from the Journalofrhr Amrr~uu~ Conrrrrr lnrrrrurr. No. 12, Proceedings Vol. 75, December 197X

PORTLAND CEMENT ASSOCIATION Research and Development / Construction Technology Laboratories

Sound TransmissionLoss Through Concreteand Concrete MasonryWalls

by Albert Litvin and Harold W. Belliston’

H BUILDINGCODESAND GOVERNMENTALagencieshave, for many years, set limits on the amount ofnoise that can be transmitted through buildingcomponents from one space to another.1-4tIn recentyears, there has been a greater awareness of theadverse effects of excess noise on personal healthand comfort, work efficiency, and privacy. Con-sequently methods of obtaining increased soundinsulation in buildings are needed.

The efficiency of a wall in restricting thepassage of airborne sound is measured in thelaboratory using the procedure outlined in “Lab-oratory Measurement of Airborne Sound Trans-mission Loss of B u i 1d i n g Partitions” (ASTME 90).5 Measurements are made of sound transmis-sion loss (STL) in decibels (db) for a series offrequencies ranging from 125 to 4000 Hz.

“Determination of Sound Transmission Class”(ASTM E 413)8 describes a method for using thetransmission loss values, determined as above, toarrive at a single figure rating for comparing theeffectiveness of walls in resisting the transmissionof airborne sound. This is defined as the soundtransmission class (STC). It is determined by fit-ting the proper STC contour (ASTM E 413) to theplot of sound transmission loss vs frequency(ASTM E 90). The STC is then equal to the trans-mission loss at 500 Hz.

A number of factors affect sound transmissionloss through walls. Weight per sq ft (mass) of thewall has a major effect, and is sometimes used as

*Principal construction consultant and former construction engineer,respectively, Construction Methods Section, Portland Cement Associ-ation.

TSuperscript nu,mbersthat are not part of measurements designate ref-erences at the end of this report.

a guide for determining transmission loss. The“mass law” indicates that transmission loss shouldincrease 6 db when either the weight or thefrequency is doubled.

Other factors that affect sound deadening char-acteristics are stiffness of the wall and presenceof resonant and coincident frequencies. Because ofoverlapping of the effects of the various factorsinvolved, it is difficult to determine by analysisthe transmission loss of a particular panel. Mostdesigns, therefore, rely on STC values determinedin the laboratory.

Most housing codes require minimum STC val-ues of about 45 for partitions where living unitsadjoin other living units. Values of about 50 arerequired where living units adjoin public spacesor service areas. The mass and stiffness of concreteand concrete masonry walls generally put themin a range where they have little trouble meetingpresent day STC requirements.

Tests reported in this paper provide STC valuesfor commonly used concrete and concrete masonrywalls and on walls that were upgraded to improvetheir sound transmission properties. For conven-ience in selecting walls for specific applicationsand STC requirements, selected STC values ob-tained by others on a variety of wail types areincluded in this report.

TEST PROGRAM

Specimens

Three basic concrete wall specimens were fabri-cated for these tests. Two were cast-in-place con-crete and the third was concrete masonry.

Structural concrete panels, 14 ft, 4 in, (4,37 m)wide by 9 ft, 4 in. (2.84 m) high, were cast inthicknesses of 6 and 8 in, (152 and 203 mm). Anair-entrained, sand and gravel concrete, repre-sentative of wall construction, was used. Concretestrengths at 28 days were 5610 and 4580 psi (38.7and 31.6 MPa) for the 6 and 8 in. (152 and 203 mm)thick panels, respectively, Corresponding unitweights of the fresh concretes were 145 and 142pcf (2323 and 2275 kg/m3). The panels were curedfor a minimum of 28 days before sound transmis-sion loss tests were started. In addition to tests onthe bare concrete panels, wall finishing materialswere added to permit determination of their effecton sound transmission.

A masonry wall, 14 ft (4.26 m) wide by 9 ft(2.74 m) high, was constructed using nominal

2 Sound Transmission Loss 7hrough Concrete and Concrete Masonry Walls

TABLE l—SOUND TRANSMISSION CLASS (STC)-PCA TESTS

Constructionof wallsTest

Descriptionof wall 4fppro:

wallweight,

psf

71.0

fleasuredSTC

57

59

62

63

No.I Side 1 Side 2

6 in. castconcretewalls

76-66

76-68

76-69

76-70

76-71

Plain Plain

Plain “Z” furring channelsplu% in. gypsumboard

72,5

Plain “Z” furring channelsPIU1 in, 6 pcf rockwool plus% in. gypsumboard

75.5

vertlcmy,24“OC. ‘ackw””’ ‘“’’h’d

~x 2 in. wood furring

?lUS1% in. 4 pcf rock-woolplus ?4 in. gypsum~oard

78.5“Z” furring plus 1in.B pcf rockwool plus % ingypsumboard

2X2,:;: \#Y,

V2°.qYmimnwollkard

24”0, C, ,Ockwool

?lain 2 x 2 wood furring plus1% in, 4 pcf rockwoolplus % in. gypsum board

73,0

96.6

101.6

63

58

——

59

/ IV;, 4 pcf ,Ock.wcol2 “2,VWtlcolly,24” O.c.

8 in. cast concrete walls

?lain

76-77 Plain

,?” Chormels, bwti.xl!y, 24” O,C /92” annum76-78 “Z” furring plus 1 in.8 pcf rockwool plus %in. gypsum board

! x 2 in. wood furring)lUS ?4 in. gypsum board

\2x2 , W,!lcally, \V,- gyp,.m wol(bowd

24” O.C

PCA Research and Development Bulletin 3

TABLE 1 fCont.140UND TRANSMISSION CLASS (STC)-PCA TESTS, ,

Description of wallTest

No,Side 1 Side 2

kpproximatewall

weight,paf

&easuredSTC

Construction of walls

I

8 in. cast concrete walls97.0 59

Plain 2 x 2 in. wood furringPIUS % in. gypsum boi

76-79\2x 2, Wrticolly, 11~~~ gyp,,m

2.?” O.c. wllb.m,d

Plain 2 x 2 in, wood furringplus 1%. in. 4 pcf rockwool plus % in, gypsuboard

76-99 97.2 63

II

8 in. lightweight concrete block walls

32.0 44

PlainPlain

Plain

76-7[

76-7(

76-7S

76-73

76-74

76-104

2 coats acrylic latexpaint

32.0

35.0

48

59

\ 2 costsIofex point

1 in. air space plus 1%Plainmetal runner with stuwith 1% in, 4 pcf rockwool plus % in, gypsuboard

38,0

89.0

57

58

1 x 2 in, furring at 16:plus % in. gypsum boi

2 x 2 in. wood furringvertically at 24 in. plusresilient channels hori-zontally at 18 in. plus 1?4in. 4 pcf rockwool plus% in. gypsum board

/I k’ . 4 M rockwool

2 x 2 in. wood furringvertically at 24 in. plusresilient channels hori-zontally at 18 in. plus 1?4n, 4 pcf rockwool plus% in. gypsum board

2ores of block grouted,)ainted

PlainIly,

Cores of block groute(plain 56

4 Sound Transmission Loss 7hrough Concrete and Concrete Masonry Walls

Refer-ence

8888888

8888888

8888

888

888

8

99

99

TABLE 2—STC VALUES REPORTED IN THE LITERATURE FOR WALLS

Description of wall

4 x 8 x 16 in. concrete masonry units, both sides plain4 x 8 x 16 in. concrete masonry units, both sides plain4 x 8 x 16 in. concrete masonry units, both sides painted4 x 8 x 16 in. concrete masonry units, both sides % in. plaster4 x 8 x 16 in. concrete masonry units, both sides % in. plaster4 x 8 x 16 h. concrete masonry units, both sides % in. gypsum wallboard4 x 8 x 16 in. concrete masonry units, both sides % in. gypsum wallboard

6 x 8 x 16 in. concrete masonry units, both sides plain6 x 8 x 16 in. concrete masonry units, both sides painted6 x 8 x 16 in. concrete masonry units, both sides painted6 x 8 x 16 in. concrete masonry units, both sides ?4 in. plaster6 x 8 x 16 in. concrete masonry units, both sides 72 in. plaster6 x 8 x 16 in. concrete masonry units, both sides % in. gypsum wallboard6 x 8 x 16 in, concrete masonry units, one side $4 in. gypsum wallboard, other

side painted

8 x 8 x 16 in. concrete masonry units, both sides plain8 x 8 x 16 in. concrete masonry units, both sides plain8 x 8 x 16 in. concrete masonry units, both sides painted8 x 8 x 16 in. concrete masonry units, both sides painted, cores grouted and

reinforced8 x 8 x 16 in, concrete masonry units, one side plaster, other side plain8 x 8 x 16 in. concrete masonry units, both sides plaster8 x 8 x 16 in. concrete masonry units, both sides plaster, cores grouted and

reinforced

Composite wall, 4 in, brick, 4 in, concrete masonry units, block side plaster8 x 8 x 16 in. concrete masonry units, one side $+ in. gypsum wallboard8 x 8 x 16 in. concrete masonry units, both sides +!! in. gypsum wallboard, cores

grouted and reinforcedComposite wall, 4 in. brick, 4 in. concrete masonry units, % in. gypsum wall

board on block side9 in, brick wall, both sides % in. plasterDouble wall of 4% in. brick leaves separated by 2 in. air cavity, no ties, ?kz in.

plaster on exposed surfaces4 x 8 x 16 in. concrete masonry units, both sides ye in. sanded gypsum plaster6 in, thick cast concrete, both sides % in, plaster

—

Wallweight,

psf

182’72230422632

21283931543527

30533073

386779

614077

60

100100

3680

ReportedS!rc

40454348504748

44464846524953

45524655

525656

535660

56

5254

4653

8 x 8 x 16 in. (203 x 203 x 406 mm) lightweight Test procedureconcrete masonry units. The units were laid usingASTM C 270 Type N7 masonry cement mortar.The mortar joints were 3A in. (10 mm) high andwere tooled on both sides of the wall. After thewall was assembled, sound transmission loss testswere made on the bare wall. Next, wall finishingmaterials were added and the tests were repeated.

The test walls and details of the surface varia-tions are listed in Table 1.

Sound transmission loss measurements weremade by the Riverbank Acoustical Laboratoriesfollowing procedures outlined in ASTM E 90-75.Measurements were made using a one-third octaveband of “pink” noise from 100 to 5000 Hz, asrecommended in ASTM E 90-75. The sound trans-mission values were tabulated at 18 specifiedstandard frequencies. All STC values were com-puted in accordance with ASTM E 413-73,

PCA Research and Development Bulletin 5

Each of the three walls was tested without anysurface treatment. Tests were next made on thewalls to determine the effect of additions to thewall surfaces. Gypsum wallboard, acoustical in-sulation, paint, and resilient fastenings wereadded.

TEST RESULTS

PCA tests

The tests are summarized in Table 1. As indi-cated in Table 1, bare concrete and concrete ma-sonry walls commonly meet current STC require-ments of 45 to 50 for buildings, However, to pro-vide data needed to obtain higher STC values,concrete walls were acoustically upgraded to de-termine values that could reasonably be achieved.The tests indicate that STC values in excess ofthose obtained would be difficult and costly toachieve. Consequently, requirements for highervalues would significantly increase the cost ofconstruction.

With the addition of wall finishes, sound trans-mission class values up to 63 were obtained onboth the 6 and 8 in, (152 and 203 mm) cast con-crete walls. It should be noted that the 6 and 8 in.(152 and 203 mm) plain walls had STC values of57 and 58, respectively. These are considerablyhigher than most current code requirements.

The plain masonry wall had an STC of 44. Mostof the normal wall finishing techniques providedSTC values that significantly exceeded presentday require men ts. Even application of paintbrought the masonry wall above the minimumrequirement of 45. The grouted wall with one sidepainted had an STC of 56, very close to that of thecast concrete walls. Based on the increase in STCobtained by the addition of furring, gypsum wall-board, and acoustic insulation, it is apparent thatthe addition of these materials to the grouted wallwould have resulted in an STC of 60 or greater.

Tests by others

Sound transmission measurements have beenmade on a wide variety of wall constructions. TheSTC values obtained from these measurementshave appeared in the literature or been reportedby governmental agencies, trade associations, andprivate companies. Table 2 lists STC values fora variety of wall types as reported by some of theabove sources,

SUMMARY

Concrete and concrete masonry walls generallymeet minimum STC requirements for partitionsin living units. Tests reported in this paper weremade on walls treated to upgrade their soundtransmission loss properties. Results indicate thatsignificant sound insulation can be obtained evenwith relatively inexpensive procedures.

Sound transmission loss tests were made on6 and 8 in. (152 and 203 mm) thick cast concretewalls and on a wall constructed of nominal 8 x 8 x16 in. (203 x 203 x 406 mm) lightweight concretemasonry units. Sound insulation was changed bythe addition of several combinations of furring,sound insulation blankets, and gypsum wallboard.Tests to determine sound transmission loss weremade in accordance with ASTM E 90. Sound trans-mission loss (STC) was determined using the pro-cedures of ASTM E 413.

With the addition of furring, insulation, andwallboard, STC values up to 63 were obtained onboth the 6 and 8 in. (152 and 203 mm) thick con-crete walls. The highest value obtained on themasonry wall was 59. However, the data indicatethat a somewhat higher STC would have beenobtained from a grouted wall with furring, insu-lation and wallboard attached,

STC values, obtained by other investigators, fora variety of concrete wall constructions are in-cluded,

ACKNOWLEDGMENTS

All sound transmission tests were performed by theRiverbank Acoustical Laboratories, Geneva, Ill., undercontract to the Portland Cement Association.

Assistance on planning the test walls and interpretingthe test results was given by Allen H. Shiner, AcousticalEngineer, Skokie, Ill., and Keith Walker, U. S. GypsumAcoustical Laboratory, Round Lake, 111, E. A. Valko,Senior Technician, assisted in preparing the walls fortesting, W. G. Corley, Director, Engineering Develop-ment Department, reviewed the text of this report andsuggested valuable changes,

REFERENCES

1. “Sound TransmissionControl in ResidentialBuild-ings,” BOCA Basic Building Code, Building Officials andCode Administrators International, Inc., Chicago, 1976Supplement, Section 522.

2. Southern Standard Building Code, Southern Build-ing Code Congress, Birmingham, 1976, Appendix E.

3. National Building Code, American Insurance Asso-ciation, New York, 1976, Section 380.13.

6 Sound Transmission Loss Through Concrete and Concrete Masonry Walls

4, “Sound Transmission Limitations,” Minimum

Property Standards for Multifamily Housing, Depart-ment of Housing and Urban Development, Washington,D. C., Apr. 1977, Table 4-4.1.

5. “Standard Method for Laboratory Measurementof Airborne-Sound Transmission Loss of BuildingPartitions,” (ASTM E 90-75), 1976 Annual Book ofASTM Standards, Part 18, American Society for Testingand Materials, Philadelphia, pp. 667-679.

6. “Standard C 1ass i f i c a t i o n for Determination ofSound Transmission Class,” (ASTM E 413-73), 1976Annual Book of ASTM Standards, Part 18, AmericanSociety for Testing and Materials, Philadelphia, pp.819-821.

7. “Standard Specification for Mortar for Unit Ma-sonry, ” (ASTM C 270-73), 1976 Annual Book of ASTMStmdamts, Part 13, American Society for Testing andMaterials, Philadelphia, pp. 243-247.

8. “New Data on Sound ReductionWith ConcreteMa-sonry Walls,” NCMA-TEK 69,A, NationalConcreteMa-sonry Association,McLean, Va,, 1978,4 pp.

9. “A Study of Techniquesto Increasethe Sound In-sulation of Building Elements,”W~le Laboratories Re-port No. 73-5, Department of Housing and UrbanDevelopment, Washington, D. C., June 1973, 216 pp.

For certainapplications, the use of sound transmissionclass(STC) valuesisnot sufficient.For thosewho requireadditionaldata,soundtransmissionlossvaluesversusfre-quency wereplotted.Figures for each specimen tested arepresented here. Test numbers shown correspond with testnumbers in Table 1of the text.

70

60

~ 50

S-y

40sGg~

~ 30K1-az

; 20

10

0

FREQUENCY, HERTZ (cycLEs PER SECOND)

J 160 I 250 I 400 [ 630 I CO

2 51000

,

I

FREQUENCY, HERT2 (CYCLES

II Erc ContourSTM E413)

Eest No. 76-68TC = 59

KZ@lm

2 510000

PER SECONO)

80

70

60

g 50

ig 40

$

~

~ 30a1-az

; 20

10

0

FREQUENCY, HERTZ (CYCLES PER SECOND)

PCA Research and Development BulIetin 7

80

70

60

g 50

10

0

FREQUENCY, HERT2 (CYCLES PER SECOND)

80

70

60

g 50

99

406G~~

~ 30E1-nz

.3 20m

10

0

FREQUENCY, HERTZ (CYCLES PER SECONO)

70

60

g 50

$9z 40Qm~~

$ 30m1-0z

; 20

10

0

FREQUENCY, HERT2 (CYCLES PER SECONO)

80

70

60

~ 50

g“

940

6g

g

~ 30akaz

~ 20z

10

0

FREQUENCY, HERT2 (CYCLES PER SECOND)

*

- Sound Transmission Loss Through Concrete and Concrete Masonry Walls

80

70

60

50

40

30

20

10

0

FREQUENCY, HERTZ (CYCLES PER SECOND)

80

70

60

50

40

30

20

10

0

FREQUENCY, HERTZ (CYCLES PER SECOND )

70

60

50

40

30

20

10

0

FREouENcy. HERTZ [cYcLEs PER SECONO)

70

60

m. 50

%9

405Gg~

z 30g

nz

; 20

10

0

FREQUENCY, HERT2 (cYcLEs PER SECOND)

PCA Research and Development Bulletin 9

70

60

: 50

g-

940

zg

g

~ 30

E0z

; 20

10

0

FREQUENCY, HERTZ (cYcLEs PER SECOND)

70

60

g 50

$-

9g 40

$

%o

5 30a+0z

g 20

10

0

FREQUENCY, HERTZ (cYcLEs PER SECOND)

70

60

g 50

~g 40

~

s(n~ 30

Enz

; 20

10

0

FREOUENCY, HERT2 (cYcLEs PER SECOND)

FREOUENCY, HERTZ (CYCLES PER SECOND)

Portland CementAssociation MemberCompanies(as of Aprtl 1980)

United StatesAetna Cement CorporationAlamo Cement CompanyArkansas Cement CorporationAsh Grove Cement CompanyAtlantic Cement Company, Inc.California Portland Cement CompanyCapitol Aggregates, Inc. (CapitolCement Division)Centex/Nevada/TexasCitadel Cement CorporationCoplay Cement CompanyCyprus Hawaiian Cement CorporationFlintkote Cement Company

Florida Mining & Materials Corp.Giant Portland & Masonry CementCompanyGifford-Hill Portland CementCompany (a subsidiary of Gifford-Hill& Company, Inc. )Ideal Basic Industries, Cement Divisionindependent Cement CorporationKaiser Cement CorporationLehigh Portland Cement CompanyLone Star Industries, Inc.Louisville Cement CompanyMarquette CompanyMartin Marietta CementThe ,Monarch Cement CompanyMonolith Portland Cement CompanyNational Gypsum CompanyNorthwestern States PortlandCement Co.OKC Corp.Oregon Portland Cement Company

Rinker Portland Cement CorporationRochester Portland CementCorporationSantee Portland Cement CorporationThe South Dakota Cement PlantSouthwestern Portland CementCompanyWyandotte Cement Incorporated

CanadaCanada Cement Lafarge Ltd.Ciment Quebec, Inc.Federal White Cement Ltd.Genstar LimitedLake Ontario Cement LimitedMiron Inc.North Star Cement LimitedSt. Lawrence Cement Co,St. Marys Cement Limited

This publication is based on the facts, tests,and authorities stated herein. It isintended for the use of professional personnel competent to evaluate the sig-nificance and limitations of the reported findings and who willaccept respon-sibility for the application of the material it contains. Obviously, the PortlandCement Association disclaims any and all responsibility forapplication of thestated principles or for the accuracy of any of the sources other than work per-formed or information developed by the Association.

------------------------ ------------------------ ----IIII E2II

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III

II KEYWORDS: acoustic insulation, acoustic properties, building codes, concrete

I

II

I panels, furring, masonry walls, noise reduction, residential buildings, sound trans-1

II

I mission, wallboards, walls. II

1I1IIIIItIIII1

ABSTRACT: Many building codes require minimum sound transmission 10SS II

values, expressed as sound transmission class (STC), of 45 to 50. Tests of sound I

transmission loss were made on 8-in. -thick (203-mm) concrete masonry walls and onII

6- and 8-in. -thick ( 152- and 203-mm) cast concrete walls finished with materials in- 1I

tended to increase sound transmission loss. Using furring, acoustic insulation, and I

wallboard attachments, STC values up to 59 and 63 were obtained for the masonryII

and cast concrete walls, respectively. Selected STCvalues, reported by other investi- 1I

gators, for a variety of walls are included for reference. II

iI REFERENCE: Litvin, Albert, and Belliston, Harold W., Sound Transmission LOSS I

II

1 Through Concrefe and Concrete Masonry Walls (R D066.O1M), Portland Cement I

I Association, 1980. Reprinted from ACl Journal, December 1978.I

II

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II

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PORTLAND CEMENT mlII ASSOCIATION

An organization of cement manufacturers to improve and extend the uses of portland cement and concrete through scientific research, engineering ficfd work, and market development.

5420 Old Orchard Road, Skokie, Illinois 60077

Printed in U.S.A. RD066.OIM