Hi, ive been lurking on the boards for maybe 6 months or so... Anyway, I have the option of building a detached theater room, nothing too large, maybe 12x18x9 or so. My question has to do with the exterior wall materials. Basically I want the walls as "soundproof" as possible, so I have the option of watching a movie with decent volume at night without waking up the neighbors.

The theater room itself will have no windows, the entrance door will be solid core, leading into a small entertainment room, which then has another SC door that leads outside. I figure the entertainment room will act as a buffer in case any sound from the theater leaks out through the door way. Again, this is completely detached from the main house.

Heres the catch though - my budgets not unlimited haha... I would guess 8x8x16" filled cmu blocks, with furring strips and drywall inside would be one of the BEST options. May be a little pricey though. How do you guys think a double stud design would work? or any other ideas?

Im not necessarily looking for the BEST option, but I guess a middle ground between performance and cost?

Thanks guys :D

Welcome to the forum. CMU block wall, then just build a 2x4 stud wall an inch inside the filled concrete clock wall, not touching the walls. Use multiple layers of drywall (cheap) and think about using Green Glue. You need to read the library of articles at Soundproofingcompany.com

Double stud is an option, study up on room within a room construction. You need to address the ceiling as well as the walls.

Thanks for the response bro.

Yeah, solid concrete seemed like the best idea to me, its just such a hassle to work with (for me anyway), and more expensive. I was thinking about doing a double stud construction for the opposite reasons, cheaper and easier to work with.. but I was wondering if anyone has "heard" a double stud wall in person. How well, audibly, it reduces the transmission of low-high frequencies.

I dunno, maybe I will just go with a cmu build.. better safe then sorry

CMU would likely take up too much space. Using double wood studs, standard drywall, fiberglass insulation and Green Glue can yield a wall in the high 60s easily. And this wall would have excellent low frequency isolation.

There's a reason you don't see CMU walls in these builds.

Thanks Ted. I could go larger on the footprint to make up for the size of the blocks but if you think double wood studs would work well I think I'd rather go with that option.

Much easier and cheaper. You can build massive walls with cheap drywall.

Sounds like a plan! Thanks bro. I guess I'll be back on the boards when everything gets rolling.

A significant key to low frequency isolation is cavity depth. Actually the big drivers are mass and cavity depth, assuming the system is already decoupled and insulated. So the heavier and deeper the wall, the lower the frequencies that you can isolate.

I see. what would you suggest as far as the spacing between the 2 walls? Like I said, I can go bigger on the footprint to make up for wall thickness, so thats not really a problem.

Well, can you consider three sheets of 5/8" on one side, attached to one row of 2x4s. R13 insulation. Then a 12" gap. Then another 2x4 wall frame with three sheets of 5/8" drywall also? So almost 2' overall depth wall

Well, can you consider three sheets of 5/8" on one side, attached to one row of 2x4s. R13 insulation. Then a 12" gap. Then another 2x4 wall frame with three sheets of 5/8" drywall also? So almost 2' overall depth wall

Ted - are you suggesting 3 sheets of drywall on the exterior, exposed to the elements? Wouldn't the last sheet be OSB instead?

Pretend wall. I wouldn't put drywall outside no matter what it was covered with

Thats a pretty beefy wall design haha. I gotta take measurements later but im pretty sure I could fit a 2' perimeter wall design in. How well would a 6" air cavity perform?

Well, more is better. More = better ability to isolate low frequencies. 6" air cavity is still excellent

great, thanks for the info. I have to jump on sketchup and see what i have to work with.