Wall Design

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phyl
Posts: 52
Joined: Fri Feb 18, 2005 5:22 am
Location: Layton, Utah

Wall Design

Post by phyl »

I'm converting a basement room to a live room for recording. Al walls and ceiling are already sheetrocked. The attached file show the basement layout.

Two of the live room walls have concrete on the other side. I plan to add another layer of sheet rock to these two walls. Ditto the ceiling.

The other two walls are of concern. I've removed the existing sheetrock from the live room side and plan to build another wall an inch away. I'll put mineral wool between the studs of both walls and use RC and two layers of sheetrock on the live room side of the new walls. My concern is the HVAC ducting that runs between the live room and control room. It's already covered in sheetrock, but I'm worried that all my effort building these new walls will be negated by sound travelling between the two rooms via the ducting.

Is there anything I can do to mitigate this? I have room below the ducting to add one more layer of sheetrock but that's about it.



My
knightfly
Senior Member
Posts: 6976
Joined: Sun Mar 16, 2003 11:11 am
Location: West Coast, USA

Post by knightfly »

The other two walls are of concern. I've removed the existing sheetrock from the live room side and plan to build another wall an inch away. I'll put mineral wool between the studs of both walls and use RC and two layers of sheetrock on the live room side of the new walls. My concern is the HVAC ducting that runs between the live room and control room. It's already covered in sheetrock, but I'm worried that all my effort building these new walls will be negated by sound travelling between the two rooms via the ducting.

First thing; if you are using separate frames, with sheet rock only on one side of each frame, then RC is a PITA for nothing. The wallboard can go directly on the stud frames with the same (or slightly better) isolation.

HVAC - bigger problem. if what's labeled HVAC is your air handler, you will need to figure out a way to make separate, dog-legged runs to each room all the way from the air handler; this is true of both supply and return air. You want separate runs, each with at least 180 degrees of bend, preferably made of Johns Manville Super Duct if you can get it.

The ducts also need to be about twice the cross-sectional area that would normally be used; this lowers the air velocity, which will have a LARGE effect on how quiet the AC is in your rooms... Steve
phyl
Posts: 52
Joined: Fri Feb 18, 2005 5:22 am
Location: Layton, Utah

Post by phyl »

Thanks Steve.

There's no way I can move the HVAC unit or the supply/return ducting.

Am I wasting my time building new walls if the ducting can't be moved? Is there any thing I can do beyond adding one additional layer of sheetrock to the ducting?
knightfly
Senior Member
Posts: 6976
Joined: Sun Mar 16, 2003 11:11 am
Location: West Coast, USA

Post by knightfly »

There's nothing I know of that will solve your problem; the duct, if it's straight between two rooms, and has registers in each room, is a free path for sound to travel. Short of walling the vents up along with the duct and doing without air in one room, there's nothing I know that will help. Even if you DID that, the OTHER room would leak into the rest of the house the same way.

Wish I could be more encouraging, but that's the physics we're forced to live with... Steve
phyl
Posts: 52
Joined: Fri Feb 18, 2005 5:22 am
Location: Layton, Utah

Post by phyl »

I appreciate your candid response Steve.

The heating vent in the live room has been blocked off for some time now; it was a wood shop before I decided to use it for recording. I may have to seal it up permanently and use a room fan to move air into and out of the room periodically.

Sound leaking from the control room through the ducting to the rest of the house is less of an issue. My biggest concern is keeping sound form the live room out of the control room.
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