RC and Additional Layer of Drywall

[Phyl]

The basement room I plan to use as a live room is already sheetrocked. It sits in a corner of the house, so behind two of the walls is concrete foundation, behind the other two walls are other sheetrocked rooms.

After reading through a bunch of posts, I've decided to put up resilient channel on the walls and ceiling and then add one additional layer of drywall. The goal is to eliminate as much leakage as possible into the control room. I realize that this is not the optimal solution but it's all the budget will allow for now.

I want to make sure this makes sense, and insure that I'm not creating some new sonic nightmare. I've read a few old posts that talk about inadvertantly creating a triple leaf system that hurts rather than helps with sound islolation.

Comments?

 

[Amped]

Anytime you add isolation, (RC) and mass (sheetrock) together, its a good thing. If you could add two layers of sheetrock it would be much better... Just remember to use the correct fasteners, dont screw into existing studwork, dont allow the corner seams to touch and use PLENTY of acoustic grade caulking. Its wont be "optimum" but should help.

 

[Rod Gervais]

Anytime you add isolation, (RC) and mass (sheetrock) together, its a good thing. If you could add two layers of sheetrock it would be much better... Just remember to use the correct fasteners, dont screw into existing studwork, dont allow the corner seams to touch and use PLENTY of acoustic grade caulking. Its wont be "optimum" but should help.

Phyl,

Amped above is mistaken.

You never want to place RC over existing drywall and then add drywall to that.

The cavity is too small for the RC to act properly - and you will lose available insolation not gain it.

For the walls that are up against the concrete - we wouldn't design for RC anyway - so just add your mass to the walls.

For the walls that are now (I assume based on your post) single stud frame walls - I would remove the existing drywall - add 4psf mineral wool insulation and then the RC with 2 layers of drywall.

Or (More ideal) I would remove the one layer of drywall from the outer face of the wall - install a seperate framed wall and the insulation to both walls - and then add one layer in the room and 2 layers on the new wall.

Same thing with the ceiling - you would be better off to just add the mass to the existing ceiling than to add RC over existing drywall - you will just be throwing your money away on the RC.

Best for the ceiling to remove the existing - install insulation - add RC - then 2 layers.

I know this sounds like throwing away a lot of money (loss of all that "good" drywall) - but believe me - it's the best investment of your hard earned cash - what you want to do is really throwing your money away.

Rod

 

[Phyl]

Thanks for clearing that up Rod.

 

[Phyl]

Yehaw - I think I done good...

I just found a contractor supply warehouse in Salt Lake City that will give me the contractor price on mineral wool.

$0.76 a square foot for 8 lb per cubic foot batts, each batt is ~3.5" thick.

 

[Phyl]

I've attached a picture of the space I'll be using.

The control room (aka family room) is sheetrocked and carpeted.

The live room has sheetrocked walls and ceiling. I plan to add another layer of rock to the ceiling and two of the walls (foundation walls). On the other two walls I'll remove the existing rock, stuff with rockwool, add resilient channel, and finish off with two layers of rock.

One problem - In the room containing the HVAC equipment, I cant put any sheetrock on the wall behind the HVAC equipment because the ducting butts right up against the wall. I've considered building a second wall inside live room to negate this.

Any comments?

 

[Phyl]

Updated picture to show where the HVAC supply and return ducting is. It's already covered in sheetrock.