Triple leaf question...it won't go away...pro advice needed.

Hi everyone, Firstly, I have another thread that I started ages ago regarding a big studio complex on a farm. You can find that here http://www.johnlsayers.com/phpBB2/viewtopic.php?t=6827&highlight=ireland You can find details about me there but as this is a different topic I will try to give as much detail here too.. I will be starting work on this studio early next year...fingers crossed...but in the meantime I have a couple of really important jobs coming up that will involve recording drums. At the moment I have setup a control room on the top floor of my 5 bedroom house...and am using another bedroom(empty) as a live room for vocal, guitar etc.. I cannot record drums there as I have neighbours 10 yards away and a fiancé who although extremely supportive and understanding...still needs to be able to watch TV and sleep without bouncing around the room... I need to buid a drum booth and have decided that it would be best to do this in the existing control room as it has just enough room and it is on the opposite side of the house to where the neighbours are. I also want it dead as it is quite a small space (open to advice here though) I have been reading this forum for ages ( I now dream in sketchup!!) and have read Rod's book several times but I am still in need of advice around a very specific matter. As you can see from my initial design, I wanted to build a booth within the room (decoupled) consisting of inside out walls (for deadening) and maximum isolation. However I have come across a couple of posts with conflicting information regarding the triple leaf system and I am a bit confused... I can understand that if I build a 1 leaf room within a 2 leaf room(drywall - air - drywall) with everything sealed then this would constitute a 3 leaf sytem and would be bad for low frequency TL. However is this the case for a non sealed system like mine, where, for 3 of the walls I have [1 layer drywall-air-1 layer drywall - framing - 50mm rockwool] and are obviously not sealed, as the rockwool layer is presented to the rest of the room? You need to look closely at the picture or the sketchup file to see this clearly...it's difficult to put into words. I suppose the main question is this... For maximum isolation, should I : 1. Remove the inner existing drywall and use it to increase the mass of the existing exterior drywall from the inside as so many people here suggest. Then build my booth with inside out walls as per the design. A definate 2 leaf system. I know this is probably the best solution but I really don't want to do this as its only really a temporary measure ( 6 months or so...) 2. Use the extra 4 layers of drywall on the existing inner drywall and not decouple the booth...just throw loads of mass at it?...eg. all the new booth walls will be inside-out but with four layers of drywall and not decoupled. 3. Go crazy and have 4 layers of drywall on the existing inner leaf and also 3/4 layers of drywall on the decoupled booth. I reckon with this I could afford to lose the 100 mm all the way round...just about....but in theory it's still a 3 leaf system...(didn't Sharwood do something similar to this?..http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8572&highlight=triple+leaf+system 4. Something else entirely?? Also the existing floor is poured concrete (don't know what depth) with 1" plywood on top. Should I float the floor as per this idea... http://www.saecollege.de/reference_material/images/My%20Wall%202.gif or could this cause more problems... Alternatively, I could always add another layer of 1" ply and I have been given a tongue and groove wooden floor which I could lay on top of this. This would give me 3" of wooden floof plus the concrete... There is no real budget but as it is a temporary solution I don't want to spend a lot on it. I have all the framing already and can get as much drywall as I need relatively cheaply. I have tried to be thorough with my information, but it's highly possible I've missed something so don't hesitate to let me know... I need to get this sorted as soon as possible...so if you can help...please do... I'd appreciate any advice on this but my main concern is a clarification on the triple leaf question...does it need to be a sealed system to be considered triple leaf?? If I got rid of the insulation layer between the existing inner drywall and the new booth drywall, would it be less of a 3 leaf system..ie. the air could move more easily(not act as a spring)??? Can you tell I'm confused?? Thanks in advance, Declan Legge, http://www.BigSpaceStudios.co.uk

one thought for the floor under the kit: http://www.dtxpressions.com/platform/ a third leaf is constituted by having a sealed air space acting as a spring - so if you build a 2-leaf isobooth in the middle of a 1-leaf room, you still don't really have a third leaf situation (or much of one - depending on the spacing between the walls of the isobooth and the exterior walls). the problem with building an isolation booth in the CR is that you'll loose precious volume in that space and change the room geometry. - I think you're better off building a proper isolation booth outside the CR. you should do some tests to determine what kind of isolation you need - check for flanking with a metal and rubber hammer on the floors and possibly walls and ceiling. also put on some low frequency sine waves and with a sound level meter determine the levels around the house and next door. this will give you a place to start.

Hi Gullfo, thanks so much for your quick reply. I like that tennis ball platform design. I think I'll give it a go and see if it works... I take it this would mean I wouldn't neccesarily have to float the floor on neoprene blocks as per John's design and just add mass to the floor instead? On that point, would a raised floor, say 1" plywood on 2" joists with 2" rockwool in between provide much more isolation than just the 1" plywood screwed to the existing 1" plywood floor? I had thought about the consequences of building in the control room and if it does cause too much of a problem I do have another room on the same floor that I can use as a control room. The reason for building the booth in this room is that it has that extra little area to the left when you come in the door which the other room doesn't and it's the furthest room away from the neighbours. Also the area under the floor of the booth in this design is our landing, which is fairly large and open so shouldn't cause as much of a problem as if it was a bedroom... The other room opposite is symmetrical so would probably make a better control room anyway. Moving the control room isn't a big deal as I will be moving it all out to build anyway. Thank you for clearing up the 3 leaf question. As long as I know that it has to be a sealed system then I think I'll be ok. I'll obviously carry out the tests you advise as well and I'll keep you posted on how it goes. Could you clarify this test -

"check for flanking with a metal and rubber hammer on the floors and possibly walls and ceiling"

Is it a case of tapping the hammer on various areas to see where the sound travels to by vibration? I will be taking photos of the process so will post them up here as I progress and obviously I'll report back on how successful it's been. Thanks again, Declan

Big Space wrote:

I take it this would mean I wouldn't neccesarily have to float the floor on neoprene blocks as per John's design and just add mass to the floor instead? On that point, would a raised floor, say 1" plywood on 2" joists with 2" rockwool in between provide much more isolation than just the 1" plywood screwed to the existing 1" plywood floor?

i think you have to do the testing first to determine what you need... adding mass might not be the only solution if the sound is tranferred directly through the floor or framing... the tennis ball bit is really a finishing touch to isolate the kit from the floor but you'll still have to deal with the sound levels in the room making its way out. and also consider even if the room is further from the neighbors, sound can still make its out through the roof and be heard... hence the testing...

Thanks for the advice Glenn, I will be doing the testing today and I'll let you know how I get on. Declan