drywall underneath the basement ceiling/Bolt system

Thank you John and all the contributors for your incredibly informative forum. I've been watching for a couple of weeks, and this site has really been informative. I won't go too much into detail about the space itself since I have two specific questions. First is in regards to sound isolation for a standard basement ceiling. A gentleman at the local hardware store suggested a plan for the ceiling that could help cut down on the noise from upstairs: adding a layer of drywall directly to the bottom of the ceiling in between the joices leaving a slight gap on each side. I think this option sounds like a lot of work and not worth the time or money. Is this a good idea, or should I concentrate my time and money on other things? Secondly, This studio will just be a recording space for solo and duo classical guitar recordings. Because of the huge lack of space, I don't intend to build a listening room... I'll just have to dream about that. The area I have available is 343cm (l) x 218cm (w) x 211cm (h). Using the Bolt system, it looks like the most I can get out of this space is 250cm (l) x 180cm (w) x 205cm (h) which makes a really tiny studio space. My question is should I design the recording studio around the Bolt dimensions or should I focus on using the space I have. An answer to this question will greatly help me draw up the room. Thank you all for your time and attention! Randall http://www.randallavers.com

There is an announcement at the top of the forum about what to do to assure getting as many responses as possible. The announcement leads to this post (click here). Actually, several people, who are experts on this forum, will most likely not reply if you don't do what is written in that post. Many others who are very helpful, will most likely not reply out of respect for the moderators' wishes. Regarding the advice you were given: It is basically correct, but incomplete. It is only half of the story. It is called "beefing up" here, and is a small part of the full treatment that you need to do. If you want to isolate your room (sometimes incorrectly called "soundproofing") then adding mass to the sub-floor above you will help, but only if it is part of a properly designed and built "room-in-a-room", based on the MSM principle. So what you'd have to do in addition to adding that mass to the floor above, is firstly to seal it all airtight with caulk (the gaps around the edges), and then to add another ceiling below that, fully decoupled from that floor, plus you'd build another set of walls around the room, a few inches away from the existing ones, but taking care that you do not create any three-leaf walls. That would be the basic idea, but its a bit more complicated than that.

Using the Bolt system, it looks like the most I can get out of this space is 250cm (l) x 180cm (w) x 205cm (h) which makes a really tiny studio space.

Bolt, Louden, Sepmeyer, Boner, whoever... It doesn't really matter which one you use, there just isn't much you can do with a nearly square section like that, without giving up a lot of space. Is there any chance you can move one of your side walls? Or gain some height somehow? - Stuart -

You say you will be using the space mostly for recording classical guitar; are there much noise coming from the outside? Otherwise I don't see the point in "soundproofing"! Make yourself a nice sounding room instead and save yourself a lot of work and money... Best of luck. HOOK

Soundman2020 wrote:

There is an announcement at the top of the forum about what to do to assure getting as many responses as possible.

Thanks for the guidance, Stuart. Got it, did a lot of reading - also got Rod Gervais book in the mail, and finally know how to spell "joist"... Evolution.

Soundman2020 wrote:

adding mass to the sub-floor above you will help, but only if it is part of a properly designed and built "room-in-a-room",

Thanks. I just noticed that the Gervais book had a very nice image of how this beefing-up works. On that note, there was a passage in the book that talked about structural limitations for applying additional layers of gypsum directly to the ceiling and under the resilient channel. In my basement, I have joists that are all 2x8 inches with a space that is 21-24 inches from center. How many layers of gypsum (on the top leaf and bottom leaf) can this sustain with no problem?

Soundman2020 wrote:

Is there any chance you can move one of your side walls? Or gain some height somehow?

The two surfaces that I cannot adjust are the two that have almost the same dimensions: Pardon my going into metric - 218cm (w) x 211cm (h) - I can extend the length of the room by a meter (from 343cm to around 450cm) but will that fix the problem?

HOOK wrote:

You say you will be using the space mostly for recording classical guitar; are there much noise coming from the outside?

Pretty quiet here. It is a residential area next to Sandvika, south of Oslo - the occasional car passing by. This space will be used as a practicing room, and isolated (hopefully) to the point of making a passable recording sound. I have a couple of Brauner mics, DAV, Merging, Quantec etc. and I know that this equipment will be able to pick-up bad isolating and awful design. I'm not asking for miracles, but at least something that doesn't sound horrendous. Thanks, Randall

Frankly, I would make myself a nice sounding rehearsal room,(studying the acoustic forum, build what ever treatment necessary ) and skip the beefing up and sound proofing all together.; the isolation doesn't make your room sound good in and of it self, the acoustical treatment does... two different things. If I´d be to much bothered by the cars passing and had to do some serious recording I´d find another venue to record in. I suspect that your room wont be ideal for recording classical guitar no mater what you do due to the limitations in space; acoustical guitar needs a rather big and "live" room to "breathe". That is my experience anyhow.... just my two cents... HOOK

HOOK wrote:

acoustical guitar needs a rather big and "live" room to "breathe".

Music in general right? This is one of the few places were bigger is actually better ;)

How many layers of gypsum (on the top leaf and bottom leaf) can this sustain with no problem?

That depends on many factors, such as the span, type of wood, and how much load the joists are already carrying. Probably your best bet is to get a structural engineer to look at it, and tell you if your "beef-up" plans are feasible or not.

(on the top leaf and bottom leaf)

If yo build a fully decoupled MSM room-in-a-room, then you don't have to consider the weight of the inner leaf, since it would be supported by the new inner-leaf walls, not by the existing floor above you. In that situation, you only need to consider the mass of the "beef". But of you go the other route, and hand your inner-leaf on RC, clips, springs, or whatever, then yes, the inner-leaf ceiling would be part of the load on the floor above.

The two surfaces that I cannot adjust are the two that have almost the same dimensions: Pardon my going into metric - 218cm (w) x 211cm (h) - I can extend the length of the room by a meter (from 343cm to around 450cm) but will that fix the problem?

Metric is fine! In fact, I prefer it! In any case, your only real option is to loose height, or make the room very narrow. Neither of those is very good. I doubt that making the room longer is going to solve anything, since the issue is with the two other dimensions, which are practically the same. - Stuart -