Help in soundproofing unusual setup (1 Viewer)

[jaidog]

I searched through the forums for soundproofing threads and found
several. But, I didn't come across any that addressed my specific
situation. I read a lot about sound channels, green glue, quiet rock,
insulation, etc, but am not sure which of these techniques or combinations
will work the best for my situation.

I am converting an existing room into a home theater. The room currently
has a vaulted ceiling. The room is in the corner of the house. Two walls are
to the exterior of the house, one wall is to a laundry room and garage. I am
not concerned about soundproofing these three walls.

Walls in home theater room:

+-------------Exterior Wall-----------------+
|................................................. ..........|
|................................................. ..........|
|................................................. ..........|
|................................................. ..........|
Wall.............................................. ..........|
Shared w/ Mbdrm .................................Exterior
|................................................. .......Wall
|................................................. ..........|
|................................................. ..........|
|................................................. ..........|
+------------------------------------------+
Garage....................Laundry Room

The wall shared with the master bdrm is my concern. A cross-section of
this wall is shown below. Behind the upper portion of this wall is our master
bedroom. This fourth wall is drywall on either side of the studs, and
also filled with sprayed-in insulation. A ceiling will be installed in this room at
a height of 8'. So, the upper portion of the wall that is adjacent to the
master bedroom will not be visible from the home theater room, and sound to
it should (I hope) be somewhat blocked by the 8' ceiling.

Cross-section of Wall Shared w/ Mbdrm:


|
|...
|.....
|........
|...........

 

[chris.big.money]

Wow I can't believe you took the time to make the drawings with dots and slashes. haha. But anyway, If you want to keep the existing drywall, then i'd suggest building a second wall that only reaches the ceiling in the theater, anywhere from a half foot or foot and a half away from the first. This begins the "room within a room" concept that is very soundproof. I'm not an expert with wall materials and such, so you'll have to look to someone else for that. But i'd say building a second wall is your best bet.

 

[David-Wright]

I agree with the above post. A double wall is a good way to go. But the seperation can be as little as 1/2". Just enough to keep the two walls from touching.

Filling the wall with rock wool will also add extra soundproffing. (well not filling it, just a layer in the new wall.

You can check my profile and posts for picutres of me putting in a double wall).

This of course assumes you have 6" to spare.

 

[chuckg]

Are you saying that you only need to soundproof the upper part of the wall? Is there no need to soundproof the lower portion?

If so, then just the ceiling will help some. Putting an extra layer of drywall on the new ceiling will help more. Piling insulation on top the new ceiling will help even more. Adding drywall layers to the upper part of the wall will help even more. Puttinga second wall on the upper portion will help even more.

There's really no such thing as soundproofing, there is only sound reduction.

 

[jaidog]

Chuck,

Exactly -- I only need to soundproof the upper part of the wall since a
bedroom exists behind the upper part. I'm not worried about the lower
section.

Based on your reply and after some phone conversations, I've decided to
add two layers of 5/8" thick drywall to the upper part of the wall with
green glue between the original drywall and the first new layer, as well as
green glue between the first new layer and second new layer. I recall
reading somewhere on this forum that I may be better off with using
one layer of 5/8" and the second layer of 1/2" drywall. Is this true?

I will probably stick with one layer of drywall on the new ceiling, but will
insulate the ceiling (both for noise reduction and to keep the heat in
the room).

Thanks to everyone for the advice.

 

[John Hile]

Hi jaidog,

The answer to your question is that it is true to use 2 different thicknesses of drywall (5/8" & 1/2") if you are not using Green Glue. This would allow the two panels to resonate at different frequencies as opposed to the panel resonating all at the same frequency. When you use Green Glue you would be damping the panel so that it does not resonate. At this point Mass is what you need so you would want to go with 2 x 5/8"

Take care,

John