3-leaf wall query

Dear all, After having posted a few times last year, and then having disappeared to do other things, I am now about to embark on a modest studio build. The first problem I have come up against is about walls. I have read and understood the theory regarding 2-leafs being optimum for STC rating, and I planned to follow a design similar to one on the SAE site. My problem comes from the fact that I have two rooms ; and the dividing wall between them is an existing red brick wall - a very common building material in the UK. On both sides of the wall I propose : Red brick wall 40mm airgap 50mm Rockwool or similar in stud frame, occasionally 'tied' back to red brick wall 15mm acoustic drywall And so my question - What happens when I do this to both sides of the same wall ? Does it become a 3-leaf system of concern, or does the fact that the middle leaf is a brick wall mean that I shouldn't worry? Are there any other, possibly better, designs bearing in mind the wall can't move ? I attach a word document showing the proposal on one side of the wall. There is a red layer immediately against the wall - this is part of a waterproofing system that is going in first. Many thanks for any comments, and please keep up the great work on this site. Peter

Aloha and welcome back, Peter :D For ease of review, I've attached your plan. :wink: Aloha 8)

Is there any reason you HAVE to put drywall on both sides of the wall? Couldn't you just cover one side with cement (I think they call it rendering on your side of the pond), and eliminate the 3rd leaf? Also, I'm not to sure about mounting the dry wall directly to the brick anyway. I think on at least one side you want to build a completely free standing stud wall with as much gap between it and the brick wall as possible. len

Kendale, Thanks for putting the plan up for me - must work out how to do that. It would be possible to render over one of the walls, but that would mean using a different method for that one wall compared to the drywall which is being used for the rest. I really like the idea of a completely separate stud wall if this is feasible. I guess it would have to be secured at the floor and ceiling which could introduce acoustic couplings of a different kind. Also, it still be a 3-leaf design, would it not ? Anyway, I'm still intrigued about the effect of the brick in a 3-leaf wall, so if anyone has knowledge of this construction type, please let me know. Thanks for the help here. Peter

The design with gypsum supported on either side of a brick centre leaf IS A 3 LEAF SYSTEM. The suggestion to render one side is the most practical way to get the same appearance on both sides. Andre