You seem to contradict yourself

I understand you say to only have two leafs of mass and an air gap. But, I was looking at some of the work in progress pics on your main site and they all show that the outer wall is framed, filled with rockwooll and plaster boarded. They then have inner walls. Surely this gives 3 leafs of mass and 2 air gaps. Outer wall - air gap -plaster board - air gap - inner wall I'm confused! Please explain

It's not that having 3 leaf systems are really bad; it's just not nearly as cost-effective... you don't get your money's worth out of adding the extra leaf. There are a lot of John's projects that are remodeling jobs, built into existing structures. The outer walls on some of them are pretty flimsy looking, and won't stop much sound from getting thru. In these cases, he wall-boards the inside of these existing outer walls, then builds the inner walls as the second leaf. Are these the projects you're looking at? Kase www.minemusic.net

Yeah mabey, so if the outer structure is brick you just need to build the inner room. There won't be any advantage of boarding of the outer brick wall before we start?

puretones wrote:

Yeah mabey, so if the outer structure is brick you just need to build the inner room. There won't be any advantage of boarding of the outer brick wall before we start?

yeah, that's right puretones.I was a bit of a disbeliever on this 2 vs 3 leaf system, but I'm convinced now that you're better off with two leaves and one gap. I'm doing double brick walls on the outside (230 mm, no gaps b/ween bricks :wink: ) and then building the inner plastered walls. cheers

Yes Kase is correct - I assume you are looking at left bank. The outer wall was full of air gaps due to the shrinking and warping of the outer cladding (1/2" x 6" hardwood) I just ignored it as a viable wall structure. Note I didn't even line it with insulation as the cost far outweighed the benefit. cheers john