Overall STC to shoot for

Ok well, now that I have to plan my whole project out to submit for permit, ( :roll: ) its got me wondering on exactly what I should be planning for to achieve the desired result. My plans are to build one big room: in my basement that I will practice, track, and mix in. Its just for me and friends, not any type of commercial facility. I would like moderate sound isolation from upstairs, but its not all that much of an issue. I also want to room to sound good. So, my plans are to build 2x4 framed walls with two layers of drywall on the "ouside" of the frame on RC. Then wood slats on the inside covering cloth/rockwool. FOr the ceiling I was planning on hanging two layers of drywall on RC from the joists. My plan was to use unfaced r-19 over the studio ceiling, under the subfloor upstairs. r-10 faced in the joists outside the "studio" in the rest of the basement. And glue unfaced r-19 to the outside of the drywalled walls. All of the STC ratings that I can find are all using two walls or a wall with drywall on BOTH sides. Since I only plan to do ONE leaf, how can I know what the STC rating would be to upstairs? Meaning the wall would have open basement then the ceiling/joists above that has some r-19. I don't want to overbuild/underbuild anything. Is the ceiling going to have comparable isolation to upstairs as the walls will have? Do I need more or less in the ceiling and or the wall? Is my question clear? Thanks.

For further clarification, look in Rod's book on page 67. Should I not both with drywall between the joists, or put up 1,2, or 3 layers, THEN two more for the ceiling?

V, my first question to you is this - why are you throwing money away on RC channel when building an isolated wall assembly - you gain nothing from it - and probably loose a little bit in the low end....... Next - you have to explain a little more about your ceiling assembly in order for anyone to answer the question - I would also have to know exactly how you are dealing with the top of wall conditions at the outside where wall meets the ceiling. Next - I would point out to you that you probably aren't ready for permit if you haven't figured out the answers to these questions yet - this because they are important to the permitting process. Sincerely, Rod

Hi Rod, thanks for taking the time.

rod gervais wrote:

my first question to you is this - why are you throwing money away on RC channel when building an isolated wall assembly - you gain nothing from it - and probably loose a little bit in the low end.......

It was my understanding that it would decouple it from the framing/floor adding STC value. But now since you've questioned it, I realize that as long as I decouple the frame wall from the floor and ceiling then it wouldn't really matter. Is that your point?

rod gervais wrote:

Next - you have to explain a little more about your ceiling assembly in order for anyone to answer the question .

Gladly: The current "ceiling" in my basement is typical construction. (from the bottom) 2x8 joists 16o.c., 3/4" subfloor, underlayment, then hardwood at the mainlevel. My plan was to us RC to decouple the studio ceiling from the floor joists/house above. Then to use r19 unfaced insulation in the cavity, damping the drywall. Then a layer of 1/2", then 5/8" drywall. Then treat for acoustics with clouds of 703.

rod gervais wrote:

I would also have to know exactly how you are dealing with the top of wall conditions at the outside where wall meets the ceiling.

I was planning on having a small 3" row/header of two layers of drywall on 2 - 2x4 top plate, and then using backer rod and caulk where they meet the ceiling.

rod gervais wrote:

Next - I would point out to you that you probably aren't ready for permit if you haven't figured out the answers to these questions yet - this because they are important to the permitting process. Sincerely, Rod

I agree that I'm not ready for permit. I actually wasn't going to get a permit at all.. Well, that is until I was coaxed into by Sharward! :evil: :D Thats why I'm trying to figure it out to the end now so I can submit for one. Does it sound (pun intended) like the walls are on even keel with the ceiling as far as isolation? Or do I need to beef up one or the other? Thanks again, I appreciate it. Ron

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