soundproofing a wall, part 1

Today, I bring you a post outlining how to start the process of soundproofing a wall.

I got a lot of help and advice on this part from the good folks at Super Soundproofing here in San Diego — I’m trying to do my best to follow their direction, but I may be missing something here and there. With that said, though, here’s how I’m doing soundproofing for the first wall between two bedrooms.

On this wall, I only pulled the drywall off of one side, so it’s not getting the full double-sided soundproofing treatment that the living room to bedroom wall is getting. But for sound transmission between two bedrooms, I think this’ll do OK.

The steps to complete the wall are basically:

  • Seal all holes and butter any boxes with acoustical caulk
  • Install cotton insulation batts between studs
  • Lay and attach mass-loaded vinyl across the studs
  • Seal mass-loaded vinyl edges with acoustic caulk, and butt joints with lead tape
  • Lay green foam tape over each stud
  • Install 5/8″ sound deadening board (like GP HushRock) on wall
  • Seal seams with acoustical caulk
  • Install 5/8″ drywall, with seams running perpendicular to sound deadening board seams
  • Seal seams with acoustical caulk, leaving room for joint compound and taping

I used an SPL meter to measure the difference sound level after adding the various pieces, with the stereo in the next room turned to 25, playing The Puppini Sisters’ “Mister Sandman”. (Not quite pink noise, but it was something fun to listen to.)

So here are the steps I followed:

First, any wall penetration on the other side needs to be sealed with acoustical caulk that dries very flexible and rubbery (and stinky for the first week), to prevent sound transmission from air gaps. As well, any box (like the electrical boxes for power and ethernet/coax) needs to be buttered up with the stuff in order to reduce vibrations and resonances of the box.

The electrical boxes:

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