How to Soundproof a Wall Using Hat Channels Part 2 How to Soundproof a Wall Using Hat Channels Part 2
This is Part 2 of a 2 part series. To return to Part 1, click here.)
Once the hat channels have been fixed and the sound dampening material applied to soundproof a wall, the soundproofing needs to be covered up and the room returned to normal. When noise vibrations are introduced into a structure from sources such as outside traffic noise, air conditioning ducting, loud music and machinery, the noise spreads easily throughout the structure because there is nothing to dampen the vibrations. To minimize these effects and absorb the vibrations, the hat channels, or resilient channels as they are commonly known, may be erected between the furring and the outer drywall. These channels work like shock absorbers dampening the vibrations being picked up by the wall and preventing them from passing through it.
Step 1: Attaching the Drywall
After the hat channels have been attached to the wall and the appropriate sound dampening materials have been fixed in place, the drywall boards should be attached to the hat channels. This is an extremely crucial part of the process and should be carried out very carefully. If care is not taken at this stage, it could negate all the work that has been done up until now. Two layers of drywall are required for the maximum soundproofing effect. The first layer is 12 mm (1/2 inch) thick. This is attached to the hat channel with countersunk screws. Great care must be taken that the screws only go into the channel and do not under any circumstances touch the inner wall, any of the furring strips or any other fixed support as this will tend to transfer any vibration being picked up by the structure onto the wall. The second drywall layer should now be attached. This layer is 9 mm (1/3 inch) thick. This layer should be affixed over the first layer, care being taken to stagger the sheets so as to cover the seams of the first drywall layer. Leave a gap of about ¼ inch all the way around the drywall panels. This is to keep them from touching the floor, ceiling or other walls thereby picking up their vibrations. The bottom of the drywall should rest on vibration absorbing neoprene pads. The gaps can now be filled with non-hardening flexible caulking material to make the wall air-tight as is possible. The wall should flex slightly and not be too rigid which would make it easier to transfer any vibrations.
Step 2: Finishing
Once the drywall is in place, the cracks where the panels adjoin each other should be taped over with acoustic tape and all dents and imperfections filled with plaster. The drywall may now be painted making sure that the caulking that was used to isolate the edges of the wall is also painted. Make sure that the entire wall is covered leaving no gaps anywhere. Gaps which make up 2 to 3 percent of the wall covering may reduce the job's effectiveness by as much as 50 percent.