TABLE OF CONTENTS The TL of a wall can be increased by separating the wall layers with an airspace to form a double-wall construction. For the wood stud constructions shown below, TL increases as the width of the cavity airspace increases. Further increases in TL can occur if sound-absorbing material is added to the airspace because absorption reduces the buildup of sound in the airspace. Shown below are example double-wall and double-stud constructions. The double-stud construction breaks the direct sound transmission path through the studs from layer to opposite layer because there are two independent framing systems separated by 1 in or more. This construction technique widely separates both sides of the wall, so the full benefit of the cavity absorption can be achieved.
| Note | TL performance of the double-wood-stud construction can be greatly improved when the weight of the gypsum board is doubled by adding a 1/2-in layer to both sides. Do not attach the additional layers to the inside of the wood stud framings because a small air gap between these two gypsum board inner layers ( < 2-in separation) can be a significant short circuit through the wall acting as a "bridge," which reduces TL by more than 10 dB at sound frequencies below 250 Hz. |
