info for soundproofing my garage

hi everybody i'm writing from italy sorry for my bad english!!! i have a garage and i want to create an home studio for recording my drums (no separate control room!) my question is about sound isolation to the outside I have no people who live around me, only other boxes, down nothing, i'm in the basement over there is a car parking so I can consider this a good starting situation the size of the room is 4,8x4 meters and 2,75m high my question is about two ideas i received for building the walls: 1) the first person suggest a "light" version: 5cm airhole from the original brick wall 5 cm of rockwoll glued to a single or two ply drywall 2) the original idea 2cm hi density rubber with 1 ply of drywall directly glued to the brick wall + 5cm of rockwool and another ply of drywall I consider the second solution a better one more isolation on bass frequencies...and I think better stc values... but the first person says that gluying something on the brick wall is not so useful, and prefer leaving some space.... what do you think? is air space better? is the layer of high density rubber not so useful if glued to the brick wall? is there another method of construction that let me utilize that material? thank you everybody MARCO

Welcome! Please update your profile with your location. In general, for isolation, having the air space is desirable. If you're just looking to finish the walls, then direct attachment is usually ok.

hi thank you for the fast reply I updated as you requested! i know air space is good but we are trying to save space because the room is not so big! so every cm is important obviously without making mistakes in construction!!! and the fact that we need no super super isolation is helping us but drums can produce 110db so don't you think that hi density rubber+ drywall, even if attached to the brick wall, is a better solution in reducing low frequiencies and volume passing outside than airspace + rockwool e drywall??? I know that it also will cost a lot more.... but that person say me that the result will not justify the money!!!! thank you MR

maybe you could post some more details such as the size of the space, photos etc so we can examine what you might do. one option may be to use inside-out walls - check out simo's build in this forum as he is doing a great job of building an inside out room. also check out lilith envy studio build and others.

hi moderator thanks for the patience I did't read the rules of the forum the first time I wrote .... I was only trying to obtain a little information by someone more expert....! but now I'm reading your manual about that specific wall construction you suggest.... and only after that I try to post some more serious information about my situation, and probably some other questions :) in the meanwhile I apologize! thank you Marco

Hi Marco, About your questions:

I consider the second solution a better one more isolation on bass frequencies...and I think better stc values...

No, the STC value of the second idea would be much worse than the first idea. In fact, it would be about the same as the STC value for the existing brick wall, as it stands right now!

what do you think? is air space better?

Yes. It is the ONLY way to build a good isolating wall at low cost.

but the first person says that gluying something on the brick wall is not so useful,

The first person is right! Brick is MUCH more dense than drywall. Gluing rubber and drywall to it will not add any useful mass to the wall, so it will not help to isolate. You would need to add about sixteen layers of 15mm drywall just to increase the isolation by 6 db!!! so one layer is not useful.

is the layer of high density rubber not so useful if glued to the brick wall?

Nope! Not useful at all. It will make very little difference to the isolation that you already have.

1) the first person suggest a "light" version: 5cm airhole from the original brick wall 5 cm of rockwoll glued to a single or two ply drywall

Well, that's kind of the idea, but not really. First, you need to seal the brick: just paint it with something that closes up all the tiny little "pores" (air holes), so that the entire wall is airtight. You could also use plaster (stucco), which would be better. Then build a wooden frame at least 10cm away from that brick wall, and nail two layers of 15mm drywall to that frame, with both layers ON THE SAME SIDE of the frame (in other words, one layer, then another layer right next to it. Fill the entire gap between the brick and the drywall with mineral wool or fiberglass insulation. You have to do that on all four sides of the room, and also the ceiling. The new frame that you build must NOT touch the brick wall or the old ceiling anywhere, not even one nail. - Stuart -

hi stuart thank you so much for the reply so I abandoned that rubber - solution and now the projects I have are in the direction you suggest! but I'm also thinking about the inside-out wall construction that is often suggested in this forum and that I know gives really good results!!! what do you think? what advantages can I obtain with the inside out walls? my friend that used it for is studio tells me that it's a more difficoult way of contruction, and so I don't know if it's even more expensive!!! really really thank you Marco

but I'm also thinking about the inside-out wall construction that is often suggested in this forum and that I know gives really good results!!!

IT gives very good results when done properly! And it is exactly the same principle as I mentioned above: you have the existing brick wall, then an air gap that is filled with insulation, then one or two layers of 16mm drywall, then the stud frame. The only difference with "inside out" construction is that the stud frame faces the room, instead of the cavity, but the concept is exactly the same.

what advantages can I obtain with the inside out walls?

"Inside out" is very useful when you don't have much space, and it saves you money on wood, since the framing faces the room and can be used to attach the acoustic treatment, instead of building additional frames (as you would with "normal" construction).

my friend that used it for is studio tells me that it's a more difficoult way of contruction, and so I don't know if it's even more expensive!!!

Yes, it is a bit more difficult to do, because you have to build the walls lying down on the floor, with the drywall on them, then lift them into place, and they are very heavy! Cost should be a bit cheaper with inside-out, if you plan carefully. - Stuart -

ok so I'm glad that I have understood more or less these wall constructions!!! One thing that I didn't understand when I was reading the john's recording manual in this section, or in other posts of the forum is: how and where the wood stud structure that we create for the new walls is fixed???? I don't know the appropriate english word....sorry How does it support itself? how does it hold up??? I think it needs something as a support to prevent collapse :) I suppose we cannot do it on the original brick wall! so is this structure connected to the floating floor? with special screws or how??? I hope the question is clear!

the lower plate is secured into the floor using decoupled anchors and the upper plate uses isolation brackets to stabilize the top. optionally, if this is not stabilized from an adjoining structure, then isolation structure needs to be self-supporting through bracing let-in to the framing or sheet material (plywood, OSB etc) to ensure that lateral (side-ti-side) shifts do not occur and the structure assemblies act to prevent inward or outward movement. typically this latter approach also uses decoupled anchors to ensure the bottom plate is stable.