Great thread. It addresses many of the same questions that I am wrestling with at the moment and it does seems like the answers are scattered all over the place. So, without trying to hijack the thread, and in the spirit of consolidation, here are a few more questions/comments/suggestions which hopefully have general interest and relevance.
Some background: I have 3 concrete blocks walls (some of which appear to be unfilled (gulp)), a concrete slab, and a poured concrete ceiling in my basement/soon to be HT. One wall, the screen wall, adjoins a tenanted flat so I do want to make sure I can crank the sound up in the wee hours without having to worry about disturbing the tenant. A fourth wall will divide the basement into an office/study and will for sure use staggered stud wall construction and an exterior door. I am located in New Zealand. No permit is required for non-structural alterations which I am assuming is the category a room-within-a-room would fall under.Questions:
- Is it even necessary to do the sound isolation thing given the concrete walls and ceiling ? I suppose I had better go through with it to justify the money I have already spent restocking on tools (mitre saw, compressor, etc) after having to leave my old ones in the US.
- What do people do for windows ?. The basement currently has an existing (single pane) exterior window. If the exit through the office is blocked by fire, I am probably going to wish I still had egress through that one window. But the current widow seems like a prime path for noise to escape..... I am thinking that a removable "plug" in front of the existing window might be in order.
What about doubling (sistering) a pair of 2*4 joists to in order to preserve height ? Actually, the ceiling is going to be black so I think a bit of sag would be acceptable aesthetically. And I can't imaging the structure based on 2*4's would actually fail.
What about going with 2*4 joists but putting a single dangling support in the centre ? Cut up a RSIC clip or something similar. Any more details on the "rubber isolating hangers from the hardware section of lowes"
What would the loss in sound isolation of RSIC clips/hat channel attached to the concrete ceiling be compared with full room-within-a-room (ie: ceiling joists sitting on the inner studs) ?
More details on options for isolating the bottom plate please.... Up until now I thought everyone just screwed, glued, or nailed (via PAT) their bottom plates directly into the concrete slab.
, Green Glue is not available here in NZ. Also 10 mm (3/8 ") drywall is standard although 13 mm (1/2") is available at a premium. In any case, regardless of thickness, do I just double-up the bare dry wall or is there something else that could substitute for the GG under the "not as good as GG but better than nothing category" ? What about good old RTV sealant ?
If one is going to build a false screen wall anyway, it seems like there is the opportunity to put the center channel above the screen. The false wall can easily be framed strong enough to take the weight of even the heaviest center. So, psycho-acoustically, is it better to locate the center above the screen or below ? Since people talk out of their heads rather than their feet that would seem to favor locating the center above the screen. Although, come to think of it, for some people, the source often seems to be half way inbetween.....Suggestion :
I was initially looking at an isolated floor but now think I will see how it goes first just having pad/carpet. Then I will try isolating the sub if necessary. Then, if that fails, I will go fully isolated floor. The point being that, apart from the hassle of ripping up an re-installing the carpet, this is one aspect of the construction that can be addressed later as needed. Like others, preserving every last inch of height is an important consideration.
Well, we are all packed and ready to go camping. That is the problem with having xmas holidays in the middle of summer. Other things to do besides working down in the basement. Did the white christmas thing the year before and I am thinking it is a bit over-rated. So, it will be a few days before I get a chance to check back in.