Eric has done some very serious installations with 100dB attenuation in one if I remember from the Acoustics egroup. I also recall him talking about short-circuiting two 180 metric tonne concrete steel sprung floating rooms by jamming a piece of wood in between them !he says that the isolation between the two rooms was so compromised you could hear a radio playing in the other when before you couldn't hear a 9mm blank , the isolation was that good. This is way way on from most studios unless your thinking of the Hidley Tracking room type places. I think his reference to butyl caulk would be for concrete to concrete gaps or wood raft type floating floors sat on 2" elastomer pads.I think pads of 13mm neoprene like most of us have here offer such a reduced performance that the caulking is less critical. I've never seen anything comparing noise attenuation of various caulks and I have looked, has any seen anything? I would like to know more on this but it seems to be a build it and measure it yourself scenario .Downsides of butyl - not paintable AFAIK and may stain drywall boards (it's quite like roof repair mastic).
It's all about balancing the isolation you require to the weakest component used. Now I thought that my drum room raft type floating floor,my wall are separate, of double 18mm chipboard/blockboard on 2X4"s on the flat on 13mm neoprene, with compressed rockwool in the void to reduced resonance, was gonna be way better for me than 30mm compressed rockwool that the floor originally rested on but things like door seals, wall construction have really meant that it hasn't made any real difference. I have used acrylic and silicone caulks for wall/ceiling junctions, some electrical holes and gaps filled with compressed rockwool (ripped into small pieces and pushed to a cable run). The compressed rockwool works really well provided you have enough thickness. This option was mentioned by Eric for use between raft floors and walls.
Cheers
