As we all know, the best way to avoid compromising our hard-earned isolation walls is to use surface-mount electrical boxes. Unfortunately, for reasons I won't go into, I was forced to use in-wall boxes.
My walls are of staggered-stud construction with 2x6 top and bottom plates with 2x4s staggered 8" on center. I was able to use the extra depth to construct wooden isolation boxes with 2x4s and 1/2" plywood. I cut three small sections of 2x4 and nailed them together in a "C" shape (one vertical, two horizontal and nailed to the first piece and then sealed with acoustical caulk). I then nailed the ends of the "C" shape to the wall to surround the electrical box with at least a 1" clearance all around the side, top and bottom and sealed it to the original stud with acoustical caulk.
Then I cut a piece of 1/2" fire resistant plywood to cover the entire back of the wooden isolation boxed, applied caulk and secured it with nails to the back, blocking all air paths through the electrical box into the wall cavity. Next, I packed rigid, fire-rated acoustic insulation into the cavity between the isolation box and the electrical box. Finally, I applied caulk to the face of the box before the drywall went on (the face sits flush with the drywall) to completely seal it.
After reading about the putty packs in the reference area, I decided that this was comparable, but I must have missed one key bit of information. Upon reviewing the reference area again (I like to sharpen up before I move on to the next phase of a project), I found this statement:
Sourcez60611 said: "If you can get at them, cover the back/outsides with putty packs. Or use plastic boxes instead of metal.
Do not fill them with rockwool -- the parts get warm in there and are designed to air cool. There's electrical code restrictions on how much room is in there (# wires, etc)."
My electrical boxes aren't filled with insulation, but they are surrounded by insulation. The safety inspector didn't seem to have a problem with them, but, as we all know , a mistake on the safety inspector's part doesn't absolve us of the responsibility of sticking to building codes (and it certainly COULD absolve the insurance company of any responsibility to pay up in the case of an accident, not to mention worse possibilities(?)).
Thanks for any responses. I'd hate to have to rip holes in my nice new isolation walls
, but safety is obviously the most important thing here.Thanks, guys!
-Dany
Here's a jpeg to clarify exactly what I did.
