Building a sound insulated room. DIY Advice?

Background: I've got a new job at a new school that's starting up next year. It's going to be a small alternative school and the building used to be a small office place. As the music teacher, I've been given the job of designing and building the music room. So, insulation and acoustic treatments here we come. I've worked in and around enough recording studios and performance spaces to know a little bit about what goes on in the construction of rooms like this but I've never done it myself. So if any of you geniuses has experience with this kind of thing I'd love advice and DIY tips.

I get an unfinished room on the end of the basement to work with. This is good because I don't have to worry about insulating one of the walls and the floor. Also, since the room is unfinished I can start from the beginning. It's also the room that has the furnace and water heater in the corner so that might present some unique challenges.

I'm going to come up with two proposals: One with no expense spared, building the room like an iso room in a studio. Sandwich walls, floating floor and all that. And a second (more realistic) proposal. I need to get this planned fast so we can put a budget on the project so we know what kind of donations we need to look for.

My next door neighbor has a recording studio in his house. He built a room inside a room, with a space of maybe 8 inches between the inner and outer walls, and then filled the space with sand. I don't know details, but it's regular wood stud construction and I assume he used some heavy plywood for the walls to withstand the weight of the sand.

In reply to stuart in mn:

Sand? Seriously? Standard construction?

Is he so desperate for the companionship of several million termites that he built them their own high rise condo?

In reply to BlueInGreen44:

Before we get into the acoustical ideas, what kind of school is this?

Furnace and water heater in an high risk occupancy (school), subterranean space (without fire exits or windows?) could have a mountain of code issues LONG before you get to make anything soundproof.

Are you asking us for hypothetical fun ideas with egg cartons, or are you looking for legitimate feedback for a small educational facility?

Is this school so small that it is better known as a home school?

In reply to SVreX:

Small school. Comparing it to a homeschool wouldn't be too far off. It's actually an pretty interesting educational concept but that's another thread in itself.

This won't be so much a classroom as it will be a glorified practice room. And I'm looking for legit feedback rather than egg carton ideas. I'd like to do this right and have it look nice as much as I can.

OK, but if it is a school (accredited or not, for profit or not, and I doubt it matters how many students there are) you can't have a furnace in a music room.

If you ever have to submit permits for anything, there won't be any such thing as "grassroots" or "DIY".

And ALL work in a school requires permits.

So, honestly, you're gonna have to have an architect. He's gonna make most of the decisions about construction techniques.

And I can't tell you how MN works, but only licensed General Contractors without any license restrictions can pull permits for work in schools in GA.

In reply to SVreX:

I honestly haven't thought too much about that aspect of the project so I'm glad you're bringing it up. I'm not the one in technically charge of the construction I just get to make the plan and then do most of the labor. I was assuming the regulations were all sorted.

I'll ask about all that tomorrow to make sure we aren't making plans that we won't actually be able to do.

for the buiding he will probably need a GC.. for the finishing, he can do it himself.

Having worked in many performance spaces.. fabrics are your friend. Open core "eggshell" foam on the walls will absorb a lot of sound and proper use of heavy fabric will absorb even more.. just be sure it is all fireproofed.

SVreX wrote: In reply to stuart in mn: Sand? Seriously? Standard construction? Is he so desperate for the companionship of several million termites that he built them their own high rise condo?

Too cold up here in Minneapolis for termites.

mad_machine wrote: for the buiding he will probably need a GC.. for the finishing, he can do it himself.

Maybe.

Laws vary by State.

stuart in mn wrote:

SVreX wrote: In reply to stuart in mn: Sand? Seriously? Standard construction? Is he so desperate for the companionship of several million termites that he built them their own high rise condo?

Too cold up here in Minneapolis for termites.

Hmmm. Right.

Dry rot?

I've spent most of my life working with many, many different alternative building techniques. I have never heard of one that blended standard wood techniques (prone to rot, etc.) with sand (prone to holding moisture).

I'd like to learn more, but it sounds pretty fishy.

I have a set of English speakers that are about as old as I am. I have to check who made them.. but they have about 50 pounds of sand in them. I have never taken them apart, so I do not know how it is encapsulated, but I have not found any rot in them.

In reply to BlueInGreen44:

The key to isolating sound is distance, and sealing up gaps and cracks. You definitely want a 2-wall build with an air-gap in between, with offset studs, insulation in each wall, and 2-layers of drywall(offset so their seams don't align) on the inside of the inner wall, and outside on the outer wall. 2x6 studs are better than 2x4, 5/8" drywall is better than 1/2", etc.

If you have the hight, build the ceiling like the walls - open up the existing ceiling and insulate up above, then drop another ceiling...again preferably 2x6 studs with 2 offset layers of 5/8" drywall and a layer of insulation in it.

Make sure all the electrical boxes and any other holes are insulated and sealed. Of course, you'll need 2 doors, one for the outer wall, one for the inner. Make them as air-tight as possible and don't use hollow-core doors.

Speaking of air-tight, that also means you'll want ducting for both cold-air return as well as your inlet side - these can be a huge source of noise, both from the HVAC system, and sound passed through from other rooms. The flexible fiberglass ductwork offers quite a bit more sound dampening than the foil-backed fiberglass panels, and forget about using sheetmetal. Also, putting 90-degree bends in the lines will cut down on more sound than you'd expect, although they also reduce flow.

If you can put down carpet, use shag and put 2-layers of padding underneath(unless you'll be rolling in/out heavy gear frequently). If that won't work, the sticky-back commercial carpet squares are great(but expensive), or if nothing else rely on area rugs and replace as needed.

That will get you a pretty quiet room, and keep your students from bothering others outside much. Now, tuning the room for standing waves, etc. is another story. The short version: egg-crate foam is nearly worthless, although true acoustic foam is quite expensive. The good news is there are some very grassroots solutions that can work effectively.

If you are going to do double layer drywall, consider 2 different thicknesses.

5/8" has mass, but 1/4" has density. They bounce different length soundwaves.

Also, a staggered stud wall as Pete described should not have a common top or bottom plate (sometimes people stagger 2x4 studs on a 2x6 plate- no good). The plate will reverb sound through the wall. They should be entirely different.

The sound walls I've built have all been assembled with glue and screws, then the screws are pulled after the glue drys (so there is only glue holding the drywall). The nails/ screws transmit sound through the surfaces.

Don't forget to use acoustic caulk to seal the plates to the floor and ceiling.

The insulation should not be standard thermal insulation. You want density, and air gaps. There is such a thing as acoustic insulation (hard to find), but some of the readily available insulations do better than others. IIRC, sprayed cellulose is much better than fiberglass.

In reply to SVreX:

Good points Paul!

We did one for a home theater that used double drywall that were two different thicknesses. You can buy a metal strip that is designed to separate the two layers and hold the drywall off the studs. We did the double drywall on both sides of a 2X6 wall with foam in between the studs. It worked real well even with the big surround sound on. When we finished the job, we all sat and watched the Matrix, drank beer and ate snacks in big comfy leather chairs.

In reply to tr8todd:

The metal strip you are referring to is typically called Z-bar. It is available from commercial drywall suppliers (but not Home Depot)

BTW, commercial performance spaces do not use stud construction for acoustical walls.

Let's see... Framework defining a hollow space with skins attached on the surfaces... Oh yeah! That's the same way you build a drum. It's a resonance chamber.

Acoustic halls are typically built of masonry (for mass), with sound absorbent fabrics, etc applied to the surface (to catch high frequencies). Anything built with stud construction is a compromise. There are, however, some pretty good compromise materials and techniques. Commercial spaces often use them for conference rooms, executive offices, etc.

Your wall doesn't matter if you don't control the ceiling plenum space and the ductwork.

Thanks guys. All your info will help a lot.

I'm assuming the design goal is to keep sound from escaping more than anything?

Then Petegossettes' suggestions are the best start, especially the point about servicesboxes and the ceiling. Also look into a drywall product called Quiet Rock instead of double panels of regular stuff. they also have sealing accessories designed around sound control.

mad_machine wrote: I have a set of English speakers that are about as old as I am....they have about 50 pounds of sand in them. I have never taken them apart, so I do not know how it is encapsulated, but I have not found any rot in them.

I'm an english speaker, but I doubt I have 50# of sand inside me. Impressive.

Most of what I was going to reply has already been stated. At my previous job life in TV production, we built a combination TV Studio / Recording Studio within our building. It was quite the learning experience. My boss was a musician and had previously worked at Muscle Shoals Sound, a very historical and respected recording studio.

Anyway, we had some of his buddies he met through there design ours, and it turned out great. As said many times above, the double wall route is the way to go, and there was much consideration about the spacing between the walls. The inside of the walls were lined with material, with a gap open between them. Inside the studio, we did the sound tiles, but not completely covering the walls. They had them laid out in a pattern that had been calculated to maximum effect. I'd love to tell you how they did this, but I have no idea. The end result was a great sounding studio. People would even drive down from Nashville to use it.

I would think there are plenty of books about this out there already. Good luck!

studs transmit sounds.. double the studs up in your walls.. but only for each side of the drywall. In other words, drywall on one side is attached to one set of studs. Drywall on the backside is attached to the other

Long shot: what about using the double wall method with insulation etc, but before the insulation is put in use something like spray bedliner to dampen out the vibration of the wood? Sorta like Dynamat but on a much larger scale?

Also: the master bath in my house backs onto the kitchen. When the tearout was done for the bath remodel, I found that the common 2x4 stud wall had been filled with regular old insulation, i.e. the pink fuzzy stuff. I can attest that with the water running full blast it can be heard in the kitchen, but just barely; normal conversation will drown out the sound. The other wall backs up to my laundry room and has no insulation, the washer/dryer are audible in the bathroom although to me it's not objectionable.

I strongly doubt Bedliner would do anything at all.

It's ok. There are typical methods to utilize. This one doesn't need a weird answer.