June_1970 — Page 13

• DOOR JAMBS SEALS

ACTIVE LEAF

(SADDLE

ASTRAGALS

AUTOMATIC

DROP SEALS

• DOOR BOTTOMS

SEALSY

To seal doors all round requires a soft type of weather stripping, and a bottom door-closer must be fitted to make the door as air-tight as reason- able.

III. Installation. A flat door, care- fully and solidly installed is important in order to achieve a good result. If the door with seals is installed too tightly or out of line, it can place great pres- sure on the latchset and hinges as well as making closing difficult.

Noise control is best achieved by

-MIN. SPACE 4*

• DOUBLE DOOR WITH CASKETS G

• SOUND LOCK =

containing the noise at its source wherever practical. Equipment rooms should be provided with properly fit ted doors with seals. In some cases a two-door unit or sound lock should be employed.

Windows

e) As with doors on interior walls, windows are the weak link in external walls, but with one difference win- dows can provide an acoustical ad- vantage by allowing a controlled *masking sound' to enter and help cover up noise from adjacent spaces. The advent of air-conditioning as a common feature in new buildings al- lows the windows to be sealed to reduce noise problems.

Two items should be taken into account: Location and selection.

windows (not two glasses in one frame); a minimum of 4in. air space, preferably 8in., between glazing; two glass panes of different thicknesses, say in. and 5/16in.; opening units over or in tracks and pressure-sealed when closed; felt or vinyl weather- stripping to both sashes; and absorbent reveals (fibreglass, carpeting, etc.)

NEOPRENE

OR VINYL

CHANNEL

CONCRETE

- WOOD -

I. Location. On the noisy sides of the building keep the number and size NEOPRENE of windows to a reasonable minimum.

FRAMING Attempt to keep opening sashes as far apart as possible, to reduce cross-talk and avoid cross-reflection. Over court- yards, windows transmit noise in both directions; use sealed windows to courtyards.

apphapple

Arrange windows to open in same direction to avoid cross-reflection.

As a general rule, the larger the pane of glass the greater the vibration and thus a lesser ability to stop noise. This can be partly offset by making the glass thicker.

II. Selection. As with doors the single, most important factor in im- proving window performance is air- tightness. This requirement can be met readily in most fixed window units, but is often not met properly at the 'fixing in' points to the window open- ing and is rarely met in most opening windows of cheaper manufacture.

In single glazed opening windows, employing even 3/8in. glass, the noise reducing ability is at best inferior and should be considered inadequate for rooms requiring above-average noise protection, or marginal for average conditions (windows when closed).

Double-glazed windows have much greater noise reducing ability. Maxi- mum ability is obtained by employing the following features: Two separate

SEAL

NEOPRENE -

Setting glazing in resilent mountings increases its noise control ability.

around the frames between the glass panes.

Window units with all these fea- tures may be considered adequate for most rooms requiring above-average noise protection and very good for average conditions (windows when closed).

Single-glazed fixed windows with 3/8in. glass and thicker can be con- sidered to have a similar ability to the double-glazed opening windows.

~50UND ABSORBER

·SILICA GEL

TI

Fixed windows double glazing mounted resiliently, with sound absorbent material in reveals - inner glass removable for cleaning.

Double-glazed fixed windows with 2in. or 3/8in. thick panes, an 8in. air space and absorbent reveals are equal to or better than the normal wall con- structions housing them.

In this comparison of windows the outside noise level would be average city noise.

Far East BUILDER, June 1970

13