You may have to fit some form of vapour barrier between the wall/rockwool before you fit the plasterboard. This can be plastic sheeting or get the rockwool that comes enclosed in its own plastic. It may be an idea to fit plastic sheeting on the outside before cladding it in feather edge - not sure on this so it may be an idea to find out from a builder or someone in the business.
The ideal way to isolate the sound from outside, is to place some form of isolator on the floor before laying the floor beams - rubber mounts are one method, though I think Wickes heavy duty 30mm slabs can be used for this. Ensure they are kept away from damp though. A plastic membrane may work for this.
I have seen floors filled with sand to act as a method of damping bass travel, so this could be used if the room within a room idea isn't required.
Then build your walls on top of the floor ensuring they don't touch the walls. Lay the roof joists across the walls as normal, but make sure they don't physically touch the ceiling joists.
Once filled with rockwool and two layers of plasterboard, you should be pretty much isolated from the outside world - though the door is always a problem. A good solid door and sealing should work reasonably well though. Bass will always travel through anything it touches, and only mass can really attenuate it. Isolating the room reduces this considerably. However, if the room is detached, then the chances of the vibrations reaching the neighbours is less, so you may not need to go this route.
Don't forget the silicon for all edges. It really is very important to stop air leaks otherwise the sound will leak out.
Ventilation should probably be ducted in and out, so maybe a couple of bathroom steam extraction units could be used. There are probably better fans for this, so look around. Try to find something that is quiet too.
Your ideas of soffits is a good one - columns and soffits are used to break up standing waves IIRC, and are often a feature of Dennis Erskin designed theaters, so for more bedtime reading, go to
www.avforums.com and lok in the home theater builder part of the forum for ideas. Try using the search for Dennis's posts, and see what he has said in the past. What he doesn't know about soundproofing isn't worth knowing.
Other than the rockwool and plaster board, I don't know about the tiles or felt being better for noise reduction. The tiles will have more mass, so may have a better absorbing effect for bass. My loft has plasterboard, vapour barrier, rockwool, roofing felt then roof tiles. Sound leakage is barely perceptable at ground level at normal volumes. I also have some extra 'walls' at lower levels, so this may be helping though.
I used some of the above methodology in my loft 'conversion', and it works very well. I tackled the echoey accoustics merely by placing carpet on the lower walls and all of the screen wall. It sounds considerably better too. I used a Behringer Feedback Destroyer to smooth out the bass response too. The room is far from ideal, but works well considering the budget that was spent on it.
As for building regs, it wouldn't hurt to ask your local council for guidance - the last thing you want is to build the room and have some neghbour whinge to the council, and have them tell you to pull it down.
AFAIK, 'temporary' buildings such as sheds or similar don't need planning permission, so you should be fine (given the size constraints mentioned earlier). I would still ask first though.
Gary.
Linear Mode
