Studio Construction Question

[woliver]

I am trying to build a small (one room) studio (primarily a practice space, but with recording equipment) in my backyard, but live in a heavily residential section of town. The city law says that no sound can be above 5db above ambient, which is about 65 db, and I have been around to quite a few of the practice studios around here and measured a lot of bands (including my own) at around 120 db and some up around 130!

I have been reading the forums on this webite and the John Sayers website, as well as many of the books recommended, and all the construction techniques, while good and VERY helpful, are tips on how to soundproof wooden structures, and even when people start from scratch a wooden studio seems presupposed and that's what most people end up building. It seems like concrete would soundproof much better, at least as one of the leaves, so why don't people build out of concrete block or brick? Is it a cost issue, or an aesthetic issue, or a sound quality issue, or what?

If concrete is actually better (I could be wrong, I can't find much information about it) what would be a good way to approach a concrete studio, very basically? i.e. use concrete for one leaf, or two? What to do about the ceiling? etc.

Thanks,
-Will

[bpape]

Building a wood structure inside and decoupled from a concrete outer shell (poured concrete or block filled with sand) can be very effective. Concrete can pass bass frequencies so you'll still want to have the other structure inside.

As for doing both of them that way, I wouldn't. You'd drive yourself nuts inside the room as you'd lose any give the wood/drywall would give that helps a bit with absorbtion.

Bryan

[clownjuggles]

I actually have a bit of experience with concrete walls. The best thing that I would suggest using is a product called AARX ICF. I used this in a former life so to speak to work with building Hotels. We had 12" Insulated Concrete Forms. 8" of reinforced concrete with 2'' of Styrofoam on either side of the wall with drywall on both inside and out (Fire commissioner never had used the product and was worried about concrete getting burned. Needless to say kinda overkill. But with 3/4'' drywall we were in the high 60's STC rating. I am shocked people don't build with ICF in this industry more often. It is far more efficient in STC, R, and speed of building. If you used sound channel inside you could easily be in the 70's and 80's with acoustic drywall and the like kind of materials.

STC RATINGS for AARX

[woliver]

Thanks guys, I read the ARXX report and will look at the website next. I have contacted a few contractors in the meantime to see how economical concrete block might be compared to wood, I will post with the results. I also asked (in response to a post some time ago by Steve (knightfly) on the John Sayers website) about the cost, and, more importantly, speed in finishing and planning, of just building a structure with 3 foot thick concrete walls. I figure that the simplicity of a structure like this, and then just having to treat the inside (which most people would do anyways) might be worth the extra few thousand dollars or whatever. But again, thanks for taking the time to reply with information!

[clownjuggles]

There is no reason why you need a 3' concrete wall.

The 8" concrete in an insulated for plus acoustical drywall will be all you need. Use a docks plank if you want a really good ceiling. spray it down with expansion foam insulation great stuff for ceilings.

[Disjointed]

3' concrete walls!!!!!!

youre a frickin wild man!!!!



seriously.. im sure there are also many other kinds of ICF available in your area...

floating room, wilthin a concrete structure seems like the best bet, --- dont forget the roof!


gl

[woliver]

There is actually a AARX dealer fairly close... I will check them out, and as a bonus AARX is supposedly a 'green' building material. In the meantime, I am seriously considering a concrete shell with a wooden interior, maybe using that green glue (or, pending some research... butyl caulking that some people say works just as well?) to help with bass frequencies. Incidentally, does anyone know (not important, just curious) why concrete passes bass frequencies? This seems counter-intuitive, and I would be interested to know the science behind it. I will try and look it up also, if anyone else is interested.

Since it seems that much (93%, according to steve) of soundproofing IS completely counter-intuitive, for example, how a 3 or 4 leaf wall will tend to hurt STC, I have another question. In a room within a room setting, the distances between the 2 walls is usually fairly minimal, in the inches range. But distance between the walls increases STC, so I assume that most people are limited by space restrictions and build out as muc as they can. But, say space wasn't a factor. Is there an 'ideal' distance between the walls? At what point, if any, does cost of building materials to build a bigger and bigger structure outweigh the gained STC? Does amount of STC gained (as intuition might suggest) decrease in proportion to distance (i.e. 6 inched will gain 10db, 12 inched will gain 15 db, 18 inches will gain 17.5 db, 24 inches will gain 18.75, etc) in any way? Is there a point at which too much distance will hurt STC?

A lot of questions, thanks in advance everyone.

[Zeitgeist]

I am seriously considering building a studio in a concrete shell too. Here in Germany one can buy precab room modules (typically used as garages) which come (and are poured) as a whole. These objects are made from 3.9" reinforced concrete. I think an inner construction with double or triple drywall as a second leave should work well. Can anyone tell me which results to expect?

I am interested in more facts about the acoustics specs and physics behind concrete.

woliver: Do you have any updates?

Thanks!