John Sayers' Recording Studio Design Forum

Sorry if this wasn't clear. Building a room inside a room with an outside only leaf on the inner building. These pre made 2x4 with 2 layers of 5/8 drywall + greenglue would be pre made on the floor and nailed to the inner room's ceiling joists as they go up. They would be the inner ceiling.
My other question was about the concrete floor. Would I be alright isolation wise with it being the only slab in the building eve though it is connected to the walls that support the upper floor. And, would the drum iso room need to be on a separate floor system?
thanks
Bill

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Bill
www.billpillmore.com

The house is finally at a point where the builder is loaning me his assistant to start the studio. This is day one where we are building the drum room (live room) in the back corner of the space.
We built the first wall and it was too heavy to lift so we pulled it up with a wench. The rest of the walls we put only one layer of 5/8 drywall before we lifted.


Day two



Day three ceiling and front wall

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Bill
www.billpillmore.com

Great pics Bill

... I love the first pic one of Day Two (it takes me at least 1hr and the help of a friend to do the same job)


Good work and best of luck with the rest of the build !

Here is a picture of the firestop on the first wall. We got the ok to use the foam so we built out the dry wall to 1/2".

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Bill
www.billpillmore.com

I'm coming to the party a bit late, and trying to understand what you are doing there. From the pics, it looks like you have a concrete wall as the outer leaf? And that you have now put up an inner-leaf consisting of three layers of 5/8" drywall on a 2x4 frame? Is that correct so far?

Question: Why is the air gap so tiny? It seems like you only have a half inch or so of air gap between your leaves! I guess you don't need much isolation, and that the inner-leaf is just for treatment, but hten why the three layers of drywall? That's rather confusing!!!

Question: I don't see any insulation in the pictures: No fiberglass or rockwool went into the air gap, from what I can see. From the last picture, it looks like you are already sealing the top of the air gap with fire rated cualk. So how are you going to get the insulation into the gap???

Sorry, I'm just having a hard time understanding the design concepts here. To me, it looks like you built a resonant cavity, not an isolation wall, and I don't understand why you would do that.


- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.

Yes


Actually it's an inch of space, there is just a strip of drywall to fill it out to a 1/2 inch for the fire stop, and I do need the isolation - thus 3 layers of drywall.



I left the 1" space so the walls wouldn't be touching. How important is insulation in that cavity? Both ends are still open and I can blow in some fiber if it's important. Just really didn't want anything against that concrete wall. Even though the exterior of the wall has waterproofing I didn't want any dampness to come in contact with the drywall wall.

I went with the 1" space because I need all the width in the room I can get.

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Bill
www.billpillmore.com

The problem is that with a very, very thin air gap, such as yours, the resonant frequency of the MSM system will be very high, thus reducing the isolation of your room at low frequencies (drums, bass).

Theoretically, the MSM resonance of your wall is about 45 Hz, which means that it will not isolate much below 90 Hz, so bass and kicks will shine through. Isn't that supposed to be a drum booth? It is not going to isolate drums very well with a thin air gap like that.

Adding insulation to that cavity would theoretically drop your MSM resonance from 45 Hz to around 32 Hz, meaning that your wall will start isolating at about 64 Hz, instead of 90 Hz. Much better for bass and drums, but still not good. Ideally, the MSM resonance of a studio wall should be below 10 Hz, if you want full spectrum isolation. You can't do that over a 1 inch air gap. With three layers of 5/8" drywall, an 8 inch gap with insulation would get you down to about 11 Hz, which is fine, and a 4" gap would get you 15 Hz, which is OK. Once your gap gets below 4 inches, the frequency just shoots up really fast.

The normal recommendation here is for 4 inches, minimum. That's why Lilith told you, on page one of your thread "Leave a 100mm gap (filled with wool)", and you said that you understood! But you didn't follow that advice, and now you have a problem.

You seem to have 8 inch air gaps on your side and front walls: You could sacrifice a couple of inches on those (and add an extra layer of drywall to compensate), to gain the space that you need for the gap on this rear wall.

Yes it is important, but I wouldn't blow in anything. I would use rock wool or fiberglass, hung from spikes on the drywall side. Blown in insulation can clump up and create flanking paths.

Did you seal that concrete before you put up the wall? You should always seal concrete or brick in MSM walls. If not then not only do you have the possibility of issues with damp, you also lose isolation, since the wall itself is porous. It compromises the "spring" part of MSM.

If you hang your rockwool only from the drywall side of the cavity, then it should not contact the concrete wall at all. EG. if you have a 4" gap there and use 3" of insulation, then you should have 1" of clear space between concrete and insulation.

But if you have a damp problem in that concrete wall then it is going to be a major problem anyway., regardless of whether or not anything touches the concrete. Damp is damp. If the air in the cavity is humid then you have a problem anyway, with or without insulation.

To be honest, I would drop that wall down again, seal the concrete properly, hang 3" of insulation on the drywall, and raise the wall again, 3" in from where it is now. To compensate a bit for the lost space, move the inner leaf of the opposite wall 3" out towards the outer leaf (reducing your gap from 8" to 5" gap) and add an extra layer of drywall to those leaves (one extra layer on each leaf to compensate for the reduced gap).

That's what I would do, if isolation is important to you. But others might have different opinions....

- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.

Thanks for this helpful information Stuart. I went back and reread the thread after your first post and saw the 100mm gap filled with wool also - embarrassing. It will be too much to remove that wall because it is tied into the rest of the room. The only thing I can think to do is to cut out holes in the outside drywall, put insulation in the wall and put new drywall on the inside of the room. I could make that wall a reflective wall and only loose 2" of floor space. Would that achieve the needed isolation results?
The builder feels confident in the waterproofing so that is probably not an issue.

Here are some more pictures and one more question. Do I need insulation touching the ceiling drywall? There is about 18" of space in the rafters with two 6" bats already.


Also here is a floor layout of the space.

Thanks

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Bill
www.billpillmore.com

Contractor had some tome to put up some more walls.





Is this too much firestop foam? Will this cause a flanking path?

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Bill
www.billpillmore.com

House is finally done and we are moved in. I have been able to work more on the studio.
All dry wall done - finally no more dust!



Starting insulation

These men did the floor in 4 hours - and did a great job.

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Bill
www.billpillmore.com

I saved the scarps from the hickory flooring for the house and some pine from the ceilings and made a slot resonator out of the ceiling in the drum room.

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Bill
www.billpillmore.com

2nd day
Building soffit closets

The speakers can slide in on these trays

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Bill
www.billpillmore.com

Got the front of the studio done. Well almost.

Ceiling done.

Wood pile going down - (what messy pictures.)

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Bill
www.billpillmore.com

Nice looking place Bill.

Hey, are you up around where Madmax is...?

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Brien Holcombe
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Sound: You can't stop it, you can only try to contain it.

I believe he's east of Greensboro - about 2 hours east of here.

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Bill
www.billpillmore.com