Is my dream of a cheap rehearsal room just that, a dream?

I need to do this as cost effective as possible. My house is half of a duplex. my family room is 12.5' x 16' (3,85m x 5m) and I want to build a sound proof(ish) rehearsal room in it. If I were to build a 2x4 structure and double sheetrock the walls and ceiling but not do anything to the floor would that be enough to keep the sound inside the house. all my windows are recently installed double panes and the structure would have a 2" gap from any wall and the ceiling of the house. I dont care if some sound escapes the room into the house, just not too much. Here's the kicker. I share a slab with my neighbor, but the only wall we share is the one car garage on the other side of the house. Is this do-able or am I dreaming? I'll throw egg crate foam or carpeting on the walls for deading. Thanks for your guidance ahead of time.

uh, if it matters, im in Southern California and I play loud hard rock.

It's not a dream...just cheap. If I had a nickel for every time someone has mentioned egg crates and carpet on the walls...I would have like, well, maybe 30 bucks. Not a lot of cash...but divided by a nickel...it is really a lot of times and is really ineffective. It is not isolation and has limited acoustical treatment. And I guess for the code guys...it is always a fire hazard....always...and the smell of chicken eggs is difficult to remediate.

I'll throw egg crate foam or carpeting on the walls for deading.

:shock: Totally agree with Brien: egg crate and carpeting is not the solution, and will do absolutely zero to isolate your room. Contrary to popular belief, these things do not and cannot stop sound getting in or out. They are not intended for "soundproofing". You can no more stop sound getting out of a room with carpet and egg-crate foam that you can stop water coming out of your kitchen tap bu putting a sponge in front of it: it simply does not work. That isn't the purpose of either foam or carpet. In general, common house / office carpet has practically no acoustical uses anyway. To isolate your room, you need mass, and lots of it. "Mass" means things like multiple layers of 5/8" drywall, all around your room, on separate stud frames separated by an air gap. That's the kind of mass you need. The laws of physics can work in your favor if you use mass wisely. But the same laws of physics rate carpet and egg-crate foam as zero usefulness for isolation ("sound proofing"). - Stuart -

Thanks guys for your input. The carpeting was solely for deadening the interior sound. It WILL be a stand-alone structure double sheetrocked. And yes, it is intended to be as cheap as possible while being effective. Im not out for a "best design" award. But by reading into your comments I think im on the right path. I'll let you know how it works out.

Two things. Update your profile so we know for a fact where you are. and 2...let's read, talk about this, and get you going in the right direction. Dead is not a quality you want in an acoustic environment, what you want is flexibility...and a dead room offers no flexibility. You suggest what seems like a double walled assembly, but you mention eggcrates and carpet. To me, you are working on limited INTERNET bs, and you have the opportunity to get this right. So from me to you, do not think it is as easy as they (those places that do not know anything about acoustics) fool you into a false sense of security...we know the enemy...we have stared it in the face and won.