On Dec 29, 3:10*pm, Boater wrote:
wrote:
On Dec 29, 1:43 pm, Boater wrote:
wrote:

I'd like to build a house, I have some ideas that I'd like to see
built into one. *Soundproofing certain rooms / walls is one thing.
2x6 top and bottom plates with staggered 2x4 studs. *That way the two
sides of the wall aren't coupled with a common 2x4 stud, but are free-
standing with an air gap between them. *Add insulation (even if it's
an interior wall) and you have a "soundproof" wall.
Uh, no...you don't. Sound will transmit over the common top and floor
plates.

No ****, sherlock... as it will between the decoupled wall surfaces,
as well as through the floor. *But this method is very effective on
reducing the amount of sound transmitted through the wall. *No one is
talking about a truly soundproofed room; that's why I called it a
"soundproof" wall (notice the "quotes"). *Everyone caught that except
for you.

What you want to do is split the top and bottom plates along the long
axis. I'd use a pair of 2x4's for the plates to isolate sound
transmission from one interior wall to another. You have to order your
door trims in a way that accommodates the thicker walls, though. I did
this to isolate laundry room sounds, and I also spec'd a Pirelli rubber
tile floor.

That would give you, at best, a minimal improvement over 2x6 plates.
The major coupling is the flat wall surfaces for music, street noises,
etc. After all, those split plates you describe are still both
attached to the same structure on the floor and in the ceiling, so
they are ultimately still tied together. And now you have an 8+" wall
instead of a 6" wall... much harder to get those door facings for
that.

In your laundry room example, the major noise is actually low freqency
vibrations being transmitted directly into the floor structure.
Beefing the floor up, with piers directly under the laundry room, is
the best way to minimize those sounds.