Clearing up Concepts

Scott Waz · Post by **Scott Waz** » Sat Oct 01, 2005 6:21 am

Hello all!

I want to understand a few topics that I have read here. I have spent the last several days reading about half of all the threads created that I found relevant. Let me first say that my understanding of what it takes to build a first class sound isolated environment is 100% better than just a week ago. Thank you to all who have contributed.

Before I continue, would you please clear up some of the techniques below:

1. All electrical outlets and light switches should be mounted on the outside of the wall so that only the cable is coming through? And then caulk heavily to fill the gap? Just like an audio harness between control room and studio?

2. An ideal wall consists of wood/metal framing with 5/8" gypsum, mud and taped, 1/2" MDF caulked at gaps, 1" fiberboard (please explain this) and one last 5/8" gypsum, mud and taped. Framing is stuffed with Rock Wool, the 3lb. variety or is it 8lb? Or is stuffed with OC 703. Acoustic caulk (many varieties) should be applied to all layers at any gap or seam including around the initial framing; floor to ceiling. TIMES TWO for double wall containment, leaving a 3", 4", 6", 12" gap of air? AND, how would you fasten all of this together? Could be a lot of screws and the danger of screwing a layer in where you have already screwed? And yes, run the Gypsum vertical and thenhorizontal never having two layers of seam in line.

3. If two control rooms are churning out Film like decibels (up to 100db) would the above described wall meet standard isolation? They would share a common 12" concrete floor and a ceiling structure that is over 6" concrete and is also the roof. There is only one shared wall, 20 feet long.

4. Should everything be on 24" centers or 16"? No wall would be a load bearing wall in the entire place. Does Rock Wool come 24" wide?

5. If ceiling hard deck height is 15', and I do a drop ceiling with "acoustic 2x2 black celing tiles" at 12 or 13 feet, can I lay 12" standard insulation on top of the grids or should I again use Rock Wool? Or something else?

6. When bringing AC into the control room and studio, a direct line from the unit should have two or three 90degree turns before you cut a rectangular hole for the metal ductwork? Should the feed remain metal to feed vents in the ceiling or should it become flex duct at that point? If you are cutting a 12" hole into the double wall containment structure, I would assume the closest to the ceiling hard deck the better, AND never run duct work between studio and CR. Each room should get it's own feed. And the return duct? I understand about not dumping air in between monitors and mixer.

7. In a semi-rectangular room, the outer wall should run the full perimeter and the interior wall should or should not be 6degree angled walls. I read conflicting opinions on whether I am builing the interior wall with angles or am I just building angled Bass traps and RFZ's after I have built an interior wall that mirrors the exterior wall. Or should I say outside leaf and inside leaf of double wall contaiment?

As you can probably tell, I have about 70% of the stuff down. I have looked at dozens of window and wall building links, I have read the SAE website and have read hundreds of threads. But I'm still a little fuzzy on concept. I hope you can tackle some or all of these little questions/affirmations so that I can seriously get to work on some design.

Kindly,

-scott

Post by **Aaronw** » Sat Oct 01, 2005 6:54 am

Greetings and Welcome to the site Scott.

An ideal wall consists of wood/metal framing with 5/8" gypsum, mud and taped, 1/2" MDF caulked at gaps, 1" fiberboard (please explain this) and one last 5/8" gypsum, mud and taped.

Depending on isolation requirements, usually you will find w/ just 2 layers of 5/8" gypsum is the typical construction that you'll need.

Framing is stuffed with Rock Wool, the 3lb. variety or is it 8lb? Or is stuffed with OC 703.

From a cost stand point as well as most construction I've seen (and have done w/ mine) is to use Rock/Mineral Wool (3 PCF).

Acoustic caulk (many varieties) should be applied to all layers at any gap or seam including around the initial framing; floor to ceiling.

Yes. Including when you stagger joints (corners), be sure to caulk between each layer before the next.

leaving a 3", 4", 6", 12" gap of air?

The more space, the better the isolation (but many variables here).

Could be a lot of screws and the danger of screwing a layer in where you have already screwed? And yes, run the Gypsum vertical and thenhorizontal never having two layers of seam in line.

Typically w/ each additional layer, you use a longer screw, being sure to use the PROPER type of screw depending on if you have wood or steel framing.

And the vertical/horizontal...Yes.

3. If two control rooms are churning out Film like decibels (up to 100db) would the above described wall meet standard isolation? They would share a common 12" concrete floor and a ceiling structure that is over 6" concrete and is also the roof. There is only one shared wall, 20 feet long.

More than likely, if you had to rooms sharing the floor, and one is not at least floating or similar, you will have flanking. There was a studio in Seattle I use to work in that had this issue. But was resolved w/ some type of epoxy rosin being more or less "mopped" on to the concrete. (Do a google search for Stepping Stone Recording or Mike Foss).

Should everything be on 24" centers or 16"? No wall would be a load bearing wall in the entire place. Does Rock Wool come 24" wide?

Each will have it's own resonate frequency. I used a combination with my construction where I had double walls. 24" & 16". And yes, Rockwool comes in 24" and 16" x 48" x what ever thickness you need.

I'm outta time to answer any others at the moment, and a few out of my expertise. Hope this helps.

Aaron

Post by **sharward** » Sat Oct 01, 2005 10:35 am

For the best isolation, surface mounting the boxes instead of making penetrations would be the best way. You may even consider running conduits on the surface (or in the walls and making a small penetration). And yes, seal them up.

Not disagreeing with that... But if you'd rather flush mount your outlets/switches, use putty pads.

--Keith

AVare · Post by **AVare** » Sun Oct 02, 2005 2:55 am

aaronw wrote:For the best isolation, surface mounting the boxes instead of making penetrations would be the best way. You may even consider running conduits on the surface (or in the walls and making a small penetration). And yes, seal them up.

Aargh! This NRC document is referenced in the links area.

Charged:
Andre

Post by **Aaronw** » Tue Oct 04, 2005 12:22 am

I don't currently have the time to read the NRC pdf, but it seems that I'm not correct on this matter. I'll edit and remove the info I posted.

AVare · Post by **AVare** » Tue Oct 04, 2005 1:03 am

Thanks Aaron. For what its worth, I have done some major boobs in the past also, and have cleaned them up as much as possible. Mind you, I haven't done any lately so...

Andre

Scott Waz · Post by **Scott Waz** » Tue Oct 04, 2005 1:30 am

Aaron, thanks for your responses. The NRC document is pretty straight forward and discusses several ways of preserving sound isolation. It's a very good link.

I'm replying quickly so that others might chime in and answer some more of my questions in my original post.

Kind Regards,

-scott

knightfly · Post by **knightfly** » Tue Oct 04, 2005 6:29 pm

Hard to improve on Brian's contributions, especially this one -

http://forum.studiotips.com/viewtopic.p ... 280e1d399c

Steve

Scott Waz · Post by **Scott Waz** » Thu Oct 06, 2005 9:01 am

Wonderful Steve. Thanks for the link!

-scott