How to reduce noise transmission between homes (apartments)

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How to reduce noise transmission between homes (apartments)

Warnock, A. C. C.

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ISSN 0701-5232

National Research Conseil national

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HOW TO

REDUCE

NOISE TRANSMISSION BETWEEN HOMES (APARTMENTS

A.C .C. Warnock

Division of Building Research National Research Council of Canada

Noise from neighbours i s a common source of annoyance i n multi- family homes. Occasionally t h e annoyance i s s o g r e a t t h a t one occupant decides t o a l t e r t h e s t r u c t u r e t o t r y t o reduce t h e i n t r u s i v e noise. This note i s meant a s a guide t o such people. It d e a l s only with sound transmission through walls and f l o o r s between adjacent homes and not w i t h a i r c r a f t , t r a f f i c o r o t h e r e x t e r n a l noises. I n t h e l a t t e r casee, sound e n t e r s t h e home most o f t e n through t h e windows.

Improvements proposed here can be c a r r i e d out by one tenant a c t i n g alone, but cooperation from t h e neighbour i s usually very useful.

Obviously i n rented accommodation the owner would have t o be consulted before making s t r u c t u r a l changes; although r e p a i r s a r e sometimes minor and inexpensive, e x t r a c o n s t r u c t i o n could r e q u i r e some f a i r l y d r a s t i c and q u i t e expensive changes.

Sound Transmission Claes and Noiee Reduction

The amount of sound energy t h a t passes through

a

p a r t i t i o n depends on t h e frequency of t h e sound;

low

frequencies

are

t r a n s m i t t e d much more e a s i l y than high frequenciee. The sound transmission

cl$ss

(STC) is

a

s i n g l e number r a t i n g system which t a k e s account of these.,frequency v a r i a t i o n s and makes it e a s i e r t o d i s c u s s t h e sound traaerpiss50n performance of b u i l d i n g s t r u c t u r e s . The higher t h e STC vukber; t h e b e t t e r t h e

w a l l ;

l.e., the g r e a t e r

the

n o i s e reduction

it:

X i can provide

between homes.

The amount of noise you hear i n your home depends on t h e amount of n o i s e

your

neighbour makes, t h e sound-transmitting propere'ies

of

t h e

common w a l l o r f l o o r , and the l e v e l of background n o i s e present i n your own home. A l l t h r e e f a c t o r s are important. For example:

;"

-

a q u i e t neighbour may

make

you t h i n k you have a good common wall;

a

noisy neighbour may

make

you t h i n k you have a bad wall;

-

i f you l i v e i n a very q u i e t home, you may be d i s t u r b e d by almost every sound even though t h e common wall

i s

very good;

-

i f your own r a d i o o r

TV

i s played o f t e n , you may not hear your neighbour (but he may hear you).

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F i n a l l y , the degree of annoyance is a personal r e a c t i o n and some people a r e m r e e a s i l y annoyed than o t h e r s .

Building r e g u l a t i o n s s i m p l i f y t h i s complex s i t u a t i o n by requiring a minimum value of STC f o r walls and f l o o r s and accepting t h a t some percentage of occupants w i l l s t i l l be annoyed even when the r e g u l a t i o n s a r e met. In Canada an STC value of

45

has been used i n building r e g u l a t i o n s f o r many years although a c o u s t i c i a n s would p r e f e r t o see values g r e a t e r than 50, such a s a r e common i n Europe. STC values around 60 can be achieved i n t y p i c a l homes and only r e q u i r e a l i t t l e b i t of care and a t t e n t i o n t o d e t a i l during design and construction.

Two-Layer Cavity Walls

The most p r a c t i c a l form of c o n s t r u c t i o n t h a t provides good sound

i n s u l a t i o n

i s

t h e c a v i t y wall o r f l o o r formed from two l a y e r s of non-porous, heavy material. There should be no r i g i d connections between the

two

l a y e r s and t h e c a v i t y should c o n t a i n sound-absorbing material. Each time e i t h e r the t o t a l weight/unit a r e a of t h e w a l l o r t h e d i s t a n c e between the l a y e r s i s

doubled, an improvement of about f i v e STC p o i n t s should r e s u l t .

It is very important t o have sound-absorbing m a t e r i a l i n the c a v i t y . Common e f f e c t i v e m a t e r i a l s include g l a s s f i b r e , c e l l u l o s e f i b r e o r rock wool thermal i n s u l a t i o n . A thickness of approximately 75 mm

is

enough except i n very deep cavity walls o r f l o o r s , where more can be added. The a d d i t i o n of sound-absorbing m a t e r i a l s such as cork o r carpet t o t h e o u t s i d e s u r f a c e s of - a wall reduces t h e sound transmission only s l i g h t l y and only a t high

frequencies.

To i l l u s t r a t e these b a s i c p o i n t s , Fig. 1 shows t h e l a r g e changes i n STC caused by q u i t e small changes i n c o n s t r u c t i o n of a simple

.

. wood stud and

gypsum board wall. - - - -

The wall i n Fig. l b uses staggered .studs to. avoid , &id connecti ons between t h e l a y e r s of gypsum wallboard. Figure

2

shows

',id

more - d e t a i l and

.

two other cornon' methods of ! avoiding. r i g i d c o n n e c t i o w bestwee* the w a l l

s u r f a c e s .,- R e s i l i e n t channels- a r e f o m e d f

roo

thin. , s t r i p s @.

i3t,eel,'

have

a

+ "2' cross s e c t i o n and

are ~ o m e t i r s

:ciClled ?Zedybars, ,(Qg.,

**,P>*.b-**

.They ?bexi commonly used i n n o i s e control'

work)

and

are

usually, .ava%lable @ l"ding',r

- - 5 < 7

supply s t o r e s . .i -.

-:c '

-.

,

Flanking Transmission

.

..

't

Sound t r a v a l s -between hbmea not only thtough t h e comkon wil<but

also

along more roundabout' r o u t e s such

as

those shown i n Figs,

3

and 4; This5!Ys known ae flanking transmission,

and

can make it very d i f f i c u l t a t

time;

t o

f i n d t h e r e a l reason f o r poor sound i s o l a t i o n .

,In

some,

cases, these f l a n k i n g paths transmit more sound than the d i r e c t ,path through :the - . corndPoaiwall. _,'

3 L.

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1) out through a window and back i n through a neighbouring window; 2 ) out through, under or around t h e edges of a door i n t o a hallway

and then i n by way of a neighbouring door;

3 ) through v e n t i l a t i o n o r h e a t i n g ducts t h a t a r e not f i t t e d with sound a t t e n u a t i n g devices.

Flanking paths a r e not always obvious, so a warning i s necessary a t t h i s point:

I f s i g n i f i c a n t sound transmission is occurring along paths o t h e r than through t h e common w a l l , then improving t h i s w a l l alone may make only a small improvement. I n some c a s e s it might be necessary t o improve o t h e r w a l l s and f l o o r s i n t h e home t o reduce noise i n t r u s i o n t o an acceptable l e v e l .

Inspection of building plans i f they

are

a v a i l a b l e , may reveal p o s s i b l e f l a n k i n g paths; i f n o t , c a r e f u l l i s t e n i n g t o i n t r u d i n g n o i s e might. Sound Leaks

Before dealing with methods t o improve walls i t i s u s e f u l t o t a l k about p o s s i b l e c o n s t r u c t i o n f a u l t s t h a t can cause a w a l l t h a t ought t o be a good sound b a r r i e r t o t r a n s m i t excessive amounts of noise. An ordinary w a l l o r f l o o r appears a t f i r s t glance t o be

a

f a i r l y . s o l i d s t r u c t u r e , without obvious holes. Stopping sound transmission however,

i s very m c h l i k e c o n t a i n i n g water. As a r u l e of thumb, i f t h e w a l l i s

not w a t e r t i g h t o r a i r t i g h t , then i t i s very 1 i k e l y . t h a t sound w i l l l e a k through it. To ensure maximum performance from a w a l l o r f l o o r , a l l f i s s u r e s and cracks, no matter how small, must be well s e a l e d using a non-hardening caulking compound. A p l a c e where l e a k s a r e very comonly found is at t h e bottom of t h e wall, where t h e baseboard may.concea1 a

l a r g e uncaulked gap where t h e gypsum wallboard meets t h e floor. ,This is

one of t h e f i r s t p l a c e s t o look f o r sound leaks. A thin-bladed k n i f e can o f t e n be used a s a probe t o i d e n t i f y a l e a k i n t h i s reglion,but i t may be necessary t o remove the baseboard t o be s u r e t h a t

'thete'Ts

enough caulking behind it. Sound l e a k s c a n a l s o be h i d d e n behind

>f.$r>er

A+ t l e t

covet p l a t e s ,

TV

antenna o u t l e t s , l i g h t switches, l i g h t fixture$,,

,or

o t h e r s e r v i c e o u t l e t s . They can a l s o occur around duct and pipe

p e n e t r a t i o n s and sometimes through i n s e t c a b i n e t s i n ~ t a l l e d ~ b a c k - t o - b a c k between bathrooms. Many of t h e s e p l a c e s

are

hidden from viey.and can be d i f f i c u l t t o f i n d , but once a l e a k o r f l a n k i n g path has been , $ d e n t i f l e d , i t rmst be plugged w i t h non-hardening caulking i f t h e h o l e

.is

small o r some s o l i d m a t e r i a l i f the hole

is

large.

The importance of t h e thorough use of caulking t o seal p e r i p h e r a l cracks and f i s s u r e s cannot be emphasized t o o strongly. Figure 5 shows some examples of where continuous beads of caulking should be applied.

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.\ Steps t o Improvement

When noise from a neighbouring home is annoying, one of the following cases a p p l i e s .

1) The wall design i s inadequate (STC l e s s than 45) and t h e c o n s t r u c t i o n i s f a u l t y a s w e l l .

2) The w a l l design is inadequate although i t has been c o r r e c t l y constructed.

3 ) The w a l l design

is

adequate (STC more than 50) but t h e c o n s t r u c t i o n

i s

f a u l t y .

.

4 ) T h e w a l l design is adequate and t h e c o n s t r u c t i o n properly c a r r i e d out.

I n the l a s t case, annoyance u s u a l l y r e s u l t s because aeighbours a r e unusually noisy, t h e people who a r e annoyed a r e very s e n s i t i v e , t h e home where annoyance i s experienced i s unusually q u i e t , o r any combination of these. I n t h i s l a t t e r c a s e t h e r e may be l i t t l e t h a t can be done except t o move, or e x t e n s i v e l y r e b u i l d t h e house.

This n o t e provides help when improvements a r e t o be made. The f i r s t s t e p

Is

t o f i n d o u t , i f p o s s i b l e , h w t h e common w a l l o r f l o o r i s

constructed and then, from t h e information i n Tables 1 t o 3, t o e s t i m a t e i t s STC.

Once t h e p o t e n t i a l STC of t h e w a l l has been estimated, Table 4

g i v e s a rough guide f o r e s t i m a t i n g t h e a c t u a l STC based-on voice transmission between homes. This t a b l e i n c i d e n t a l l y .expresses t h e d i f f e r e n c e i n privacy provided by d i f f e r e n t c o n s t r u c t i o n s i n everyday

terms. (It may be necessary t o get h e l p from t h e neighbours t o apply t h i s table.)

A 'large discrepancy between t h e two STC values means s e r i o u s sound l e a k s o r f l a n k i n g paths.

These

should be looked i f o r and r e p a i r s drade. I n many

cases

t h i s . w i l l - eolve t h e problem and may be a l l t h a t

is

- - , reasonable t o do..

When a l l obvious l e a k s and f l a n k i n g paths have been d e a l t with and n o i s e i n t r u s i o n

i s st111

a problem, then t h e common

wall

o r f l o o r has t o be improved. The following s e c t i o n s g i v e some guidance on how-to do it.

METHODS

FOR

_IMPROVING

_WALLS _AND _F'LOORS

The b a s i c i d e a

is

t o make t h e c o n s t r u c t i o n a s s i m i l a r a s p o s s i b l e t o one of t h e b e t t e r c o n s t r u c t i o n s i n Tables 1 t o 3.

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Stud Walls

With stud walls containing a t l e a s t 75 mm of sound-absorbing m a t e r i a l i n t h e c a v i t y and constructed with e i t h e r staggered s t u d s , separate s t u d s , wood studs with r e s i l i e n t channels, o r metal s t u d s , a l l t h a t is required

i s

t o caulk a l l leaks and add e x t r a l a y e r s of gypsum wallboard to build one of the b e t t e r c o n s t r u c t i o n s i n Tables 1 o r 2. It does not matter much t o which s i d e t h e e x t r a gypsum board

is

applied. Thus, i f a design c a l l s f o r a t o t a l of four l a y e r s of wallboard, and the e x i s t i n g wall has only one on each s i d e , two more can be added t o one s i d e only. It is good p r a c t i c e , however, t o s t o p leaks on both s i d e s of the w a l l , which obviously requires t h e

cooperation of your neighbour.

I n some homes, e s p e c i a l l y o l d e r homes converted t o apartments, t h e s e acceptable types of s t u d systems w i l l not have been used and there m y not be any sound-absorbing m a t e r i a l i n the cavity. I n t h i s case the best procedure i s t o remove t h e p l a s t e r o r wallboard from one s i d e and convert the wall t o one of the p r e f e r r e d types. R e s i l i e n t channels can be used o r , preferably, a s e p a r a t e s t u d s t r u c t u r e can be constructed.

The maximum number of l a y e r s of gypsum board shown i n the t a b l e s f o r s t u d walls, is four. There would st1 11 be some b e n e f i t i n adding one mre

i f desired. Thus, i f t h e o r i g i n a l c o n s t r u c t i o n has one l a y e r of board on each s i d e , another t h r e e o r f o u r l a y e r s could be added t o one s i d e .

Concrete Walls

*

Table 3 shows t h a t i t is r e l a t i v e l y easy t o get good sound i n s u l a t i o n from a block o r s o l i d concrete wall. The most common problem with concrete block walls i s missing o r inadequate caulking where the gypsum wallboard meets t h e f l o o r . This allows sound t o leak through t h e porous blocks. I f no leaks o r flanking p a t h s have been i d e n t i f i e d and i f the sound i s o l a t i o n

i s

not adequate, then t h e b e s t procedure

is

t o add e x t r a l a y e r s of wallboard using t h e techniques shown i n Figs. 6 t o 8. . .

The method i l l u s t r a t e d i n Fig. 6 can be used on any w a l l no matter how i t is constructed. A frame t h a t does not contact t h e e x i s t i n g w a l l

is

constructed from woodz o r metal s t u d s , e'ound-absorbing m a t e r i a l

as'

plae'kd:

i n t h e c a v i t y and two l a y e r s of gypsum board a r e applied, taped, cau1ked:bnd f i n i s h e d i n t h e usual way. The disadvantage of t h i s method

is

t h e l o s s of approximately 120 mm from t h e length o r width of the room. The s t u d s i z e

.

and a i r space

can

be reauced, but t h i s reduces t h e e x t r a sound i s o l a t i o n provided p a r t i c u l a r l y a t low frequencies.

Less space

is

used by t h e two methods i l l u s t r a t e d i n Figs. 7 an'd 8. I n Fig.

7,

wood f u r r i n g s t r i p s a r e n a i l e d o r screwed t o t h e e x i s t i n g w a l l and r e s i l i e n t channels a r e then secured t o the f u r r i n g s t r i p s t o give a '-

r e s i l i e n t connection. I n Fig. 8, t h e r e s i l i e n t channels a r e screwed d i r e c t l y t o the wall surface. This l a s t method i s not as good a s t h e previous two because t h e a i r space is smaller. There might be no improvement a t low frequencies

.

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Floors

Excessive noise transmission through f l o o r s can be p a r t i c u l a r l y

d i f f i c u l t t o d e a l wlth because i n a d d i t i o n t o a i r b o r n e sound, there is a l s o the problem of f o o t s t e p s and o t h e r impact noise. Fortunately, changes made t o reduce airborne noise w i l l a l s o reduce the transmission of impact noise. It i s common knowledge t h a t adding carpet and underlay t o the walking s u r f a c e w i l l g r e a t l y reduce f o o t s t e p noise but t h i s only s l i g h t l y reduces airborne noise transmission. If the occupant i n an upper apartment does not wish t o use c a r p e t s , t h e r e I s l i t t l e t o be done t o a l l e v i a t e f o o t s t e p noise problems except t o improve the c e i l i n g .

As with w a l l s , t h e p r i n c i p l e involved with f l o o r s i s t o improve t h e c o n s t r u c t i o n by a l t e r i n g i t t o more c l o s e l y resemble t h e i d e a l , i.e., two l a y e r s of m a t e r i a l r e s i l i e n t l y connected, with sound-absorbing material i n t h e cavity.

J o i s t Floors

Figure 9 gives t h r e e examples of good f l o o r c o n s t r u c t i o n using s o l i d wood j o i s t s . The use of s t e e l j o i s t s o r wood t r u s s e s would not change t h e sound transmission s i g n i f i c a n t l y . These t h r e e f l o o r s a r e the sane i n p r i n c i p l e . M~st of t h e weight of the assembly

is

i n t h e f l o o r . This is because it is not p r a c t i c a l t o have any more than two l a y e r s of gypsum board suspended from r e s i l i e n t channels and i t is p h y s i c a l l y e a s i e r t o add heavy m a t e r i a l s on top.

Y

I f a j o i s t f l o o r is judged inadequate and i f a l t e r a t i o n s can be made from both s i d e s , then i t is a s t r a i g h t f o r w a r d task t o a l t e r the c o n s t r u c t i o n so t h a t it resembles one of those shown i n Fig. 9. I f t h e c e i l i n g i s

d i r e c t l y attached t o t h e j o i s t s , then i t should be removed, r e s i l i e n t

channels i n s t a l l e d and sound-absorbing m a t e r i a l added i f necessary. Gypsum wallboard

is

a f a i r l y heavy, r e l a t i v e l y inexpensive m a t e r i a l t h a t

can

be used t o add weight on f loore, but i t should be protected with a new wood s u b f l o o r on top t o avoid damage.

With f l o o r systems where t h e f l o o r and c e i l i n g are r e s i l i e n t l y

connected but t h e r e

is

no sound-absorbing m a t e r i a l i n t h e

j o i s t

space,

i t might be p o s s i b l e t o have sound-absorbing m a t e r i a l blown i n t o the c e i l i n g c a v i t y through small holes.

I f a l t e r a t i o n s t o a j o i s t f l o o r can only be made from below, t h e b e s t approach

is

t o remove t h e e x i s t i n g c e i l i n g and a l t e r t h e f l o o r using t h e technique shown i n Fig. 9b. The gypsum board can be added t o the underside of t h e f l o o r above i n pieces conveniently s i z e d t o make working e a s i e r . Once e x t r a weight has been added t o t h e underside of t h e f l o o r , t h e c a v i t y can be p a r t i a l l y f i l l e d with sound-absorbing m t e r i a l and then up t o two l a y e r s of gypsum board can be attached t o r e s i l i e n t channels t o form t h e c e i l i n g . The assembly should be thoroughly caulked i n t h e usual way.

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F l o a t i n g F l o o r s

I f t h e r e i s a s o l i d connection between t h e f l o o r and c e i l i n g and a l t e r a t i o n s can only be made from above, then a d i f f e r e n t approach using a f l o a t i n g f l o o r i s necessary.

The b a s i c p r i n c i p l e of a f l o a t i n g f l o o r

is

shown i n Fig. 10. The r e s i l i e n t l a y e r reduces t h e d i r e c t t r a n s m i s s i o n of sound from the upper l a y e r s t o t h e s t r u c t u r e below. The s t i f f n e s s of t h e r e s i l i e n t l a y e r i s important. Glass o r rock wool f i b r e s h e e t s w i t h a d e n s i t y of about

100

kg/$

( 6 l b / f t 3 ) g i v e a c c e p t a b l e f l o o r d e f l e c t i o n s (about 2 mm) and reduce t h e impact transmission. Other r e s i l i e n t m a t e r i a l s , such a s rubber, could be used t o g e t h e r with d i f f e r e n t sound-absorbing materials. The new s u r f a c e l a y e r should be r e l a t i v e l y heavy; f o r example, a wood subf l o o r r e s t i n g on t h e b a t t e n s , two l a y e r s of gypsum wallboard and then an upper l a y e r of wood t o p r o t e c t t h e gypsum.

Concrete F l o o r s

Concrete f l o o r s are u s u a l l y t h i c k enough, and heavy enough, t o p r o v i d e r e a s o n a b l e sound i s o l a t i o n , e.g., a 1501nm s o l i d c o n c r e t e s l a b provides about STC 52. I f a n o i s e t r a n s m i s s i o n problem e x i s t s with

a

concrete f l o o r , t h e n e i t h e r a f l o a t i n g f l o o r should be added on top (Fig. 10) o r a

r e s i l i e n t l y suspended c e i l i n g should be added below u s i n g t h e techniques shown i n Figs. 6 t o 8 f o r walls.

Conclusion

It is not d i f f i c u l t t o o b t a i n high values of sound i s o l a t i o n between homes. It only r e q u i r e s reasonable design and a t t e n t i o n t o d e t a i l .

Although i t is u s u a l l y more troublesome t o improve a c o n s t r u c t i o n a f t e r i t is b u i l t , i t can u s u a l l y be done, as d e s c r i b e d i n t h i s note. The c o s t , however, may be considered too high.

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TABLE 1: Wood Stud Walls

(A11 walls have a t l e a s t 75 mm of sound-absorbing m a t e r i a l i n t h e c a v i t y )

STC Construction Description 49 Staggered wood s t u d s , s i n g l e l a y e r

gypsum board each side.

53 Staggered wood s t u d s , double l a y e r

gypsum board one s i d e , s i n g l e l a y e r o t h e r side.

56 Staggered wood s t u d s , double l a y e r gypsum board each s i d e .

56 S i n g l e wood s t u d s , r e s i l i e n t channel, double l a y e r gypsum board each s i d e .

56 Double wood s t u d s , s i n g l e l a y e r gypsum board each s i d e .

60 Double wood s t u d s , double l a y e r gypsum board one s i d e , s i n g l e l a y e r o t h e r side.

63 Double wood s t u d s , double l a y e r gypsum board each side.

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9

TABLE 2 : Metal S t u d Walls

( A l l w a l l s have a t l e a s t 7 5 mm of sound-absorbing material i n the c a v i t y )

STC Construct i o n Description

46 metal s t u d s , s i n g l e l a y e r gypsum board each s i d e .

49 metal s t u d s , double l a y e r gypsum board one s i d e , s i n g l e l a y e r o t h e r s i d e .

-- - -

56 metal s t u d s , double l a y e r gypsum board each s i d e .

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TABLE 3: Concrete Block Walls

Approximate

S i d e 1 ' S i d e 2 STC

Gypsum board d i r e c t l y

a p p l i e d As S i d e 1 Gypsum board on wood

f u r r i n g s t r i p s A s S i d e 1 52

Sound-absorbing m a t e r i a l and gypsum

board on wood f u r r i n g Gypsum board d i r e c t l y

s t r i p s a p p l i e d 5 5

Sound-absorbing

material and gypsum

board on r e s i l i e n t Gypsum board d i r e c t l y

channels a p p l i e d 5 8

-

25 mn a i r space, 40 ann

m e t a l s t u d s , sound-

a b s o r b i n g m a t e r i a l and Gypsum board d i r e c t l y

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1 I

TABLE 4 : Estimating Sound Transmission C l a s s

Rat l n g Privacy A£ _forded

Normal speech e a s i l y understood

Normal speech a u d i b l e but not i n t e l l i g i b l e Loud speech a u d i b l e and f a i r l y understandable

40

_{Loud speech audible but not i n t e l l i g i b l e}

45 Loud speech b a r e l y a u d i b l e 5 0 Shouting barely a u d i b l e 55 Shouting not a u d i b l e

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STC

Fi

STC

(a

F I G U R E 1

C H A N G E S I N S O U N D T R A N S M I S S I O N CLASS

CAUSED

BY C H A N G E S I N C O N S T R U C T I O N

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S O V N D A 8 S O R B I N G M A T E R I A L GYPSUM B O A R D RE G Y P S U M G Y t S U ) B O A R D . S I L I E N T C H A N N E L M A T E R I A L P S U M F I L L E R STRIP S O U N D A B S O R I I N G M A T E R I A L

\

F I G U R E 2 T n t E E M E T M O D S OF OBTAINING S T R U C T U R A L S E P A R A T I O N I N W O O D S T U D W A L L S

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--+ F L A N K I N G T R A N S M I S S I O N

-

D I R E C T T R A N S M I S S I O N F I G U R E 3 F L A N K I N G PATHS IN B U I L D I N G S A T T I C SPACES C FIGURE 4 F L A N K I N G I N A T T I C OR BASEMENT SPACES E R E X T E N D WALL T O R O O F OR D I V I D E A T T I C SPACE W I T H F.ULL-HEIGHT BARRIER

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HEADER PLATE

ATT INSULATION

GYPSUM BOARD

(a) CAULKING AT EDGE OF CEILING

GYPSUM BOARD

CAULKING

,

FLOOR

(b) .CAULKING AT BASE OF WALL

F I G U R E 5

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.AYERS

LLBOARD

OR

STUDS

S O U N D

A B S O R B I N G

M A T E R I A L

FIGURE

6

M E T H O D FOR I M P R O V I N G A N Y WALL

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RESILIENT CHANNEL WOOD FURRING 2 LAYERS OF EXISTING GYPSUM BOAR WALL \ S O U N D A B S O R B I N G MATERIAL FIGURE 7

METHOD FOR I M P R O V I N G A WALL U S I N G FURRING A N D RESILIENT CHANNELS. N O T QUITE AS G O O D AS METHOD I N FIGURE 6 AT LOW FREQUENCIES

J-

E X I S T I N G WALL +2 LAYERS OF G Y P S U M BOARD ,RESILIENT F U R R I N G C H A N N E L

.SELF -TAPPING SCRE

tifi1

FIGURE 8

M E T H O D FOR I M P R O V I N G A WALL U S I N G RESILIENT C H A N N E L S O N L Y . N O T AS G O O D AS M E T H O D I N FIGURE 7 AT L O W FREQUENCIES

(20)

2 x 2" WOOD FURRING

_/

rl

SAND

SOUND ABSORBING MATERIAL

RESILIENT CHANNEL 2 LAYERS OF GYPSUM BOARD ATTACHED TO UNDERSIDE OF FLOOR

MATERIAL

\

"RESILIENT CHANNEL

F I G U R E 9

S O M E EXAMPLES O F J O I S T F L O O R C O N S T R U C T I O N S P R O V I D I N G G O O D A C O U S T I C A L PERFORMANCE

(21)

,CAULK / F I N I S H F L O O R SOFT M A T E R I A L 2 LAYERS G Y P S U M BOARD A R O U N D EDGES T O PREVENT C O N T A C T F I G U R E 10 E X I S T I N G F L O O R A B S O R B I N G LAYER EXAMPLE OF A F L O A T I N G F L O O R