[badger]

I have read for a few hours about ht room contruction and had a few questions about ceilings. Later this week I will be building fiberglass insulated staggered stud walls with double 5/8 drywall sheets in my 1 car garage to turn it into a ht room.
The dimensions are 17L x 12w x 7.75h for before the walls. The floor is tar (driveway material) and will be framed in with an air space directly above tar, insulation, plywood, and carpet pad then carpet. This garage is touching the house with one wall and the ceiling. It is outside the house's foundation and the wall touching the house is insulated and has a layer of plywood, drywall and will have the false wall built next to it. The ceiling has my bedroom above it and is bare studs atm.
I was reading the best ceiling to have would be double drywall utilizing clips and furring channels with insulation above it. I was thinking why not run 2 x 6s across the top of the staggered studded walls so the drywall is an inch away from the studs in the floor above. I was thinking this would decouple the ceiling from the studs above and reduce the transfer of sound. Pls let me know if this is a viable option or I’m just building a room that will fall on my head. thank you for your input

 

[bpape]

That's absolutely a viable and excellent way to provide great isolation (and save money as you then don't need clips and channel).

Just be careful that 2x6's are sufficient. With double drywall and a 12' span, I'd personally play it safe and use 2x8's.

Also, if you really want good isolation, make sure that the walls are not connected directly to the joists above except via DC-04 clips

Bryan

 

[badger]

That would be sweet but from the spec sheet I just read I would need one about every 4ft and within 8" of intersections. So I would need about 36 of the clips? Not sure if I am calculating it correctly. 36 clips at 6$ a pop is about $200. Is that about right? or do I need more/less clips.

forgot to mention there is a 6L x 3d x 6h space at the end of room.

 

[bpape]

That's about right though you can get the clips for less than that.

Also, for any wall that's not directly shared with another space, you don't need staggered studs, just a plain wall will work fine inside another wall so there's a lot of money saved there - likely more than enough to pay for the clips.

Bryan

 

[badger]

sweet, thank you for the great info!

 

[bpape]

The trick to make that work is that you don't want to drywall the 2 faces of the 2 walls that are in the cavity between walls. Just drywall (or outer sheething) the outside of the outer wall and the room side of the inner wall. Fill both walls and the cavity between with insulation.

Bryan

 

[Ted White]

http://www.soundproofingcompany.com/library/articles/room_within_a_room/

This may help.

 

[bbieger]

First things first, on your floor, I don't see why you would need to frame and insulate. Just get yourself some 1" pink foam board (that's extruded foam, not expanded foam). Lay that down and seal all the seams with foil tape. Now you have an insulated vapor barrior. Then you can lay down some tounge and groove plywood and lay your carpet right over the top of it.

In regards to your ceiling, while framing another set of ceiling rafters will benefit your isolation, in terms of cost benefit you might as well just run clips and channel on your existing joists and do the double drywall thing. Clips and channel for that room will run you about $250. You will spend at least that much on 2x8's. The person I spoke to on the phone about my basement said STC's of lower 60's with channel and double drywall. That's pretty good, and probably higher than just double drywall and decoupled framing. Just a guess, but seems fairly logical to me...

 

[bpape]

You can do pretty well with clips and hat channel as long as you still do double drywall and green glue. The completely isolated framing though will still do a better job as there is zero contact with the framing above.

Bryan

 

[Ted White]

It's just as Bryan says. Decoupled "floating ceiling" joists will do a better job than clips as long as the framing is stable. Standard lumber can twist as is acclimates. The ideal material would be I Joists 9 1/2". No twisting after installation and they can span wonderfully.
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