How to Increase the Soundproofing of an Existing Wall
- 1). Determine if existing walls have any insulation between the studs. This can be done by cutting a small hole in the plaster or drywall and looking in. If no insulation is present, you will need to fill in the walls with foam insulation.
- 2). Use a stud finder to locate all studs in the wall. Mark on the wall where each stud is located. At the top of the wall, between each stud, cut out of the drywall or plaster a small hole about 3 to 4 inches across. Using an insulation sprayer like you would use to spray insulation into an attic, fill the spaces between the studs with cellulose insulation up to the ceiling of the room. Use sheetrock and joint compound to fill in the holes. Repeat for all walls you want to be soundproof.
- 3). Using 1x2 furring strips, build a second wall against the first wall. Sound is basically waves or vibrations. Ways to reduce the intensity of these waves are by air, mass and distance. Building a second wall will create more distance for the waves to travel, more mass through a second layer of sheetrock, and air as you will leave the space between the 1x2 strips empty. Build the wall by taking two of the furring strips and attaching the the top and bottom of the wall horizontally. When attaching the 1x2 furring strips to the existing wall, use the silicone caulk between the wood and sheetrock. This will help reduce the transmission of vibrations. Use nails to hold the strips to the wall. Finish by attaching furring strips vertically about 18 inches apart. Run these strips between the top and bottom furring strips.
- 4). Complete the second wall by attaching sheetrock to the furring strips. Between the joints use the silicone caulk as a sealant to prevent any sound waves from penetrating. Repeat building the second wall for all walls you want soundproofed.
- 5). Replace all hollow-core doors with solid wood or steel doors as the increase in mass will help deaden the sound waves. Complete with a rubber weatherstripping around the entire door.
- 6). Finish the effort by caulking all electric boxes, wall plates and light switches with the silicone caulk. Remember, every crack or seam gives sound a path where it can travel so the more of these you can eliminate the more soundproof your room will be.
- 7). Repeat all steps on the ceiling.