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The drywall panels used in many modern homes are not an effective way to soundproof a wall. This is because the paneling is normally affixed directly to a metal or wooden frame and will vibrate when struck by sound waves from the other side of the wall which are transmitted through the rigid frame. Sound waves may also be picked up from the ceiling or other walls and be radiated into a room because there is nothing there to dampen them. Sound waves may also vibrate through to adjoining floors and also through ceilings. Noise radiates quite easily through structures as there is little there to restrict it.
A sound dampening layer can be constructed by affixing specially formed metal channels known as hat channels, because their shape is like a top hat, to the existing wall then attaching sound proof material to the channels. The hat channels reduce direct contact with the walls and offer a way to dissipate sounds entering the dead air space.
Step 1 – Attach Hat Channels to Wall
The hat channels, made of either aluminum or galvanized steel can be attached with screws to an existing wall or to furring strips equally spaced and running vertically up the wall. The hat channels are mounted at right angles to the furring strips with the larger of the two flanges uppermost. To add an extra degree of soundproofing, isolating sound clips, the so called whisper clips, may be used. These are attached to the wall or to the furring strips and the hat channels are then clipped in to these stand-off type clips to further isolate the channels from the wall. The channels may be cut to the desired length using a hacksaw. Ensure that the opening of the ground or bottom channel is facing up. The opening in the other channels should face down.
Step 2 – Fix Sound Absorbing Material Between the Channels
A soundproofing barrier material can be used to cover the wall like wallpaper using contact adhesive applied with a roller, before the furring strips or hat channels are fixed. The thickness of the soundproof barrier will depend on the level of control required. Sound absorbing insulation material may then be applied to the wall between the hat channels or may even be held in place by the hat channels. Sound absorbing tape may then be applied along the length of the hat channels. When the dry wall is attached to the channels, the tape acts as a sound absorbing cushion. Adding mass between the channels will improve the wall’s sound absorbing qualities. Its thermal insulation will also be improved by adding blanket insulation. Ensure when fixing the sound absorbing material that it is rigid. This is so that it remains vertical when installed between the supporting channels.