Subject:Soundproofing: How to build free standing walls for a room within a room?

Posted by: Will_3

Date:3/4/2004 6:11:51 PM

We want to sound proof 2 walls from outside noise for our small video studio... (Studio size about 20 ft wide by 23 ft long by 12 ft high.)

As suggested by others we are considering building two walls, just inside our two our outside walls... to keep outside sounds outside. (We plan on leaving about a 1" air space, if that is adequate.)

We have been advised to not attach the new wall to it's sister wall... and also to not attach it to the ceiling. (The floor is a concrete slab with tile. We will carpet the studio when done.)

But... the ceiling is 12 feet high and the wall will be 12 feet high... how can we keep it vertical, stable and safe? (Since we can't attach it to the ceiling or the wall just 1" away?)

(Our front and back walls need no protection as we have rooms behind them we can control.)

The walls we are trying to protect are the two sidewalls... one has a tenant on the opposite side... the other is the end of the building with AC compressors about 15 feet away... on the next property. (Woops, we didn't notice that until we had signed the lease and started renovations.)

Thanks for any suggestions and comments.

Will

Subject:RE: Soundproofing: How to build free standing walls for a room within a room?

Reply by: vanblah

Date:3/4/2004 7:31:32 PM

You build them the same way the other walls are built. Anchor it into the slab. Use joists across the top just like regular walls and ceilings etc. You can't just build the walls themselves ... you have to build a room within a room.

You could build a giant box that is supported by a few beams and only touches the slab at a few spots.

Doug

Subject:RE: Soundproofing: How to build free standing walls for a room within a room?

Reply by: drbam

Date:3/5/2004 6:30:28 AM

There's a ton of info on the web regarding soundproofing and acoustic treatment. There are also some forums directly related to this. Do some searches and you'll come up with enough information to keep you busy for a year! ;-)

drbam

Subject:RE: Soundproofing: How to build free standing walls for a room within a room?

Reply by: Rednroll

Date:3/5/2004 10:06:53 AM

Like Vanblah said, if your object is to not connect to adjoining walls and ceilings you basically have to build a room within a room. Giving it's own ceiling and such. You will find a lot of information on the web to deaden the sound. Most of these recommendations are very costly. I worked in a studio where they purchased a special accoustic 1/4" black rubber type of material that was layored within the walls. I think they ended up paying close to $40K for the acoustical treatment of the walls when all was said and done and the walls where like 2.5' in thickness. I built my own studio and didn't have that kind of budget. I used double 5/8" drywall on one side, 5/8" and 1/2" drywall on the other side. Inbetween was some insulation, with a 2.5" air gap. My room materials ended up costing about $1200. The end result was, that I found my room more sound isolated than the $40K special acoustic material studio. Drywall is a great sound deadener material and is very economical. The key is to use double layer drywall, the thicker the better. The reason why you use different thinknesses (ie the 1/2") on both sides, is that if the thickness is the same, then certain frequencies can resonate through both sides of the wall. When you have 2 different thicknesses, then what maybe able to get through the first wall, will hopefully be stopped by the second wall because it isn't able to keep resonating through the material at that same frequency. It's also important to keep some air inbetween the walls. Air is actually a good sound deadening material. If you have solid adjoining materials, they may start to resonate together allowing more sound to go through the wall. So what happens is that the sound goes through the first set of drywall, where it loses energy, then hits the air, then get's absorbed by the insulation, then hits the second layer of drywall, where at this time hopefully loses most of it's energy to make it out to the studio. The thicker the wall the bettter. The same thing with your glass, if you're making a window, use at least 2 layers and make sure the thickness of each layer is of different thickness, and each is angled differently. There's some good information on the web for properly choosing the angles of the glass, given the thickness of the wall and glass. Also do the same thing to the ceiling and use double layers of drywall.

Subject:RE: Soundproofing: How to build free standing walls for a room within a room?

Reply by: metrazol

Date:3/5/2004 11:38:36 AM

Good advice Rednroll.

My lab recently ( 6 months ago now...yikes) sound proofed my office during our remodel. My strongest recommendations are to do two of the cheapest things that give you the best reduction, and Red mentioned both:

1. Sheetrock: Double the thickness of a normal construction. Trust me. It costs only a fraction more and has the best bang, or lack of, for the buck. Rednroll couldn't be more right about that. It's cheap, it's solid, and 2 layers will kill a lot of DB.

2. Auralex foam: Buy it, apply liberally. It comes in nice blocks you can glue to the walls of your studio, is easy to install, and is pretty inexpensive. Also provides massive isolation and dampening, while coming in 20 or so stylish colors ( I got stuck with white...I wanted orange.)

Oh, and Rednroll, the black rubbery stuff is called Sheetblok. It is AMAZING. 6db quieter than the equivalent thickness of lead. Oh, and it costs a fortune and a half. It's fabulous, but is insanely expensive to install (unless you're handy with glue and a staple gun), not to mention the cost per roll...