Hi there "A.H.I.", and welcome to the forum!
Sorry about the delay, but somehow your thread slipped though the cracks, and I didn't even have it lined up for a reply! So I'm glad you bumped it...
He plays drums (quite loud rock) and wants to be able to practice with his band without disturbing too much the rest of the house.
Tall order! Not impossible, but not as easy as you would hope. Drums easily put out 115 dB, and for most people in a residential setting "inaudible" means less than 40 dB. That's 75 dB of transmission loss you need!
Most home studio builders are pleased to get more than about 45 dB of isolation, really happy to get over 50 dB, and ecstatically, screamingly exuberant if they manage to achieve 60 dB isolation. 70 is about the realistic limit for the average house. So hopefully you'll be able to live with something in the above range. Don't forget that each time you go up 10 dB in isolation, it means you are stopping then times as much energy, which makes it ten times harder (not to mention more expensive....).
So realistically, I would suggest that you set a goal of 50 dB, which is do-able and should attenuate the drum sounds enough so they are still audible, but just faintly, distantly.
To keep the drums level tamed we want to build a kind of floating booth
Hmmm.... are you SURE you want to try floating it? Take a look at this:
http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173
made out of Roxul
Contrary to popular belief, insulation does not stop sound. It cannot be used alone to isolate. It can be used as PART of an isolation system, yes, by by itself it isn't very useful for isolating a room.
5/4" X 6 Cedar planks
Sounds expensive! 5/8" type X drywall is probably a lot cheaper, and much more dense. Are you planning to use those only because you can get them very cheap? But trying to seal all those joints is not going to be easy....
with plexiglass insert
Plexiglass isn't much use for that. Yes, drums shields for stage work are made of plexiglass, and they work fine to do what they are designed to do, but plexiglass simply does not have enough density to be useful for the type of isolation you are talking about.
A portable room within a room sort of thing.
"Room in a room" is most definitely the way to go, but I very much doubt it will be portable! You need huge amounts of mass to get even 50 dB of isolation.
The windows in the basement will be "filled" with wooden frames with Roxul in them,
Once again, that won't make any difference at all, for the same reason as above: mineral wool does not stop sound, it jus absorbs it, which is NOT the same thing.
Think of it this way: if you take a kitchen sponge, it is really great at mopping up water that spilled some place you didn't want it. But if you hold that same sponge over the end of the tap and turn the tap on, water pours right through, unimpeded: the sponge does not stop water, and insulation does not stop sound. Insulation is used in acoustic
treatment, which is totally different from acoustic
isolation. And it is also used as part of an isolation system, but on its own, it does very, very little to isolate. Think of it like this: air is great for holding up cars! Provided that you put it inside a tire.... Air by itself, without the tire, is pretty useless for supporting your car. It only works as part of a system. Same with insulation: it needs to be used correctly within an isolation system, not by itself.
but the outdoor leakage is less of a concern in this case.
Actually, that isn't the case: isolation is "all or nothing". Sound travels in weird and wonderful ways that aren't intuitive, at first, but consider this: if sound gets out through your basement window, then it can get in just as easily through the bedroom window right above it.... or across the street... or the window of the cop car parked outside, as he comes to shut you down for violating the loca noise regulations...
we plan to do a suspended ceiling (2 X 1/2" gyprockdrywall suspended with ceiling hangers or resilient channels).
That will work, and will get you somewhere in the mid 40's of isolation, provided that you do the rest of the room to the same level (including windows, doors, HVAC and electrical),and provided that you seal the sub-floor above you really well.
remove existing floating floor (built on concrete with 2X3 covered with 3/4" plywood) down to concrete, and lay compressed Roxul mats covered with 2 layers of MDF or Plywood.
That's not a floated floor. Not the original nor the one Rod describes. Rod's is more of a partly decoupled, partly damped floor. It isolates somewhat, but isn't strictly speaking a floating floor. It would be much easier to just build a drum riser using that same concept (see Glenn's design for that), rather than attempting to do the entire floor. Much cheaper, too!
3) We are planning to build an independent wall around the bedroom (see the attached plan please). Right now it is a 2X3 structure with drywall, so we are going to strip it down to wood on the practice room side and fill it with Roxul and then build another wall in front of it with double 5/8" drywall and Roxul.
Right! That is, indeed, the way to do it.
Or the concrete wall with earth on the other side can dampen the sound?
Concrete is extremely massive: About 3 to 4 times as dense as drywall. It is also much, much thicker. Dirt is a fantastic acoustic damper. So yes, concrete with earth behind it is really, really good at stopping sound. So those concrete walls certainly can be your outer leaf. All you need to do then is to build the inner leaf.
The walls are not attached to the concrete walls of the basement and have about 1" of air gap between them (between the 2X3 structure and the concrete that is).
How are the attached at the top? If they are nailed to the floor joists above, then you have a problem. If they are free-standing and support their own ceiling, then you are in luck!
We were thinking about leaving the 2X3 structure in place, replace the fluffy pink fiber by Roxul, to install a resilient channel and to top it off with some a double layer of 1/2" drywall.
If the inner-leaf frame is already fully isolated from the outer-leaf, then you do not need resilient channel. The purpose of RC is to decouple, but if hte framing is already decoupled, then you don't need to do it twice.
For the ceiling, we are planning to use the Genie Clips with a hat channel and two layers of 5/8" with GreenGlue between them.
Why the difference between the inner-leaf walls and the inner-leaf ceiling? For the ceiling you are planning to do it with lots of rigid mass (2 x 5/8) and also Green Glue, which is great, but the walls you plan to do with only flimsy, flexible, low-mass 1/2" drywall, and no Green Glue? Why the difference? It would be better to do it all with 2 x 5/8" fire rated drywall and Green Glue.
We are about to start rebuilding very soon (after weeks of demolition) and it would be awesome to hear your suggestions before we start wasting supplies
Before you start building, I'd suggest that you do a complete design of the room in SketchUp and post it here, along with pictures of the basement where you plan to build this, so that we can take a look at the details. After all, you are planning to spends thousands of dollars here, so it is important to make certain that everything is in place before you start! For example, you haven't mentioned anything about your HVAC plans, or your electrical plans, and those are both absolutely critical for good isolation, just as much as your plans for doors and windows. So I'd suggest that you take the time to do a full and compete design, then post it here, then build.
I'm looking forward to following your thread, as it sounds like an interesting space you have there. Plus, I really like Canada!
- Stuart -
Would you happend to know a good tutorial for idiots?