Fastening multiple layers of gyprock(drywall)

We're about to do the gyprocking (drywall) on the OUTER wall of the tracking room and I just wanted to confirm the method with which to attach multiple layers. I've read and re-read the 'complete section's description of this and just wanted to make sure I have it clear. I'm planning on using 2-3 layers, of 'gyprock soundchek' (above average density), depending on what the guy thinks the walls will hold. Either 2 layers, one layer of 13mm and one of 10mm, or 3 layers, one layer of 13mm, a layer of 10mm and then another layer of 13mm. I was going to screw the first layer into the wood studs, with the normal glue, and half schedule fastening (Should I apply something before putting the next layer up?) The put up the second layer, with half schedule, screws going through the first layer and into the wooden frame. Then the outer layer with full schedule screws going all the way through the 3 layers into the frames. No sheet should touch the floor, right? (I'll use sealant below the sheets) How can you tell where the studs are after putting up the first sheet? What should I put between the sheets and how? It'd be better to have no joins in adjacent layers right next to each other, am I right? Is this method a good way to do it? I basically just want a detailed description on fastening multiple wall layers, as it is not a normal thing to do and the gyprock guy gave me a funny look when I mentioned it. Any advice, instructioons or links pertaining to this unusual building technique would be very helpful. Thanks for anything you can do! :-) Also, should I put a lot of fibreglass batts in this wall? Or concentrate on the INNER wall later on down the track? Or both? Thanks!

I'm hardly qualified to answer questions, but I believe you may want to look at this thread http://www.johnlsayers.com/phpBB2/viewtopic.php?t=502

Actually,since I posted that nearly a year ago I've had numerous phone and email conversations with people who build soundproof walls on a daily basis - and even though that post is true, it's not the WHOLE truth. I can see that I need to go back in time and "clean up" some things to reflect newer information and studies, like one finished just recently in Canada. Basically, the information in the above linked post stops being true the minute you either use separate frames or insert Resilient Channel in a wall or use light gauge steel studs - and the PITA of using "soundboard" in a wall system (and full-sheet lamination, for that matter) is just not worth the effort. For the most recent study of wall construction and performance, go here http://irc.nrc-cnrc.gc.ca/fulltext/ir761/ and download the entire PDF (around 6 megs) - it shows constructions, STC ratings, and TL for each band separately, for nearly every combination of wall materials that's practical. Hope that helped... Steve

To tell where the stud are after you put up the 1st sheet - just put a mark on the floor and on the ceiling with a pencil where the studs are and then you can snap a chalk line down the wall when the 2nd sheet goes up. I screwed both layers into the studs and put joint compund between the 2 layers. The 2nd layer I put in less sctews.

Hey Steve, you da man. I've recently gone on downloading sprees that resulted in a massive megabyte-o-rama of reading material on my drive from every agency I could find, regarding sound TL (even aviation and renewable energy commissions, the armed forces, plus all the Canadian, British, IRC, as well as insulation and engineered wood associations).. ..and that left me eyeballing one bigole haystack from hell, groping for a decent sewing needle. Just one needle to help patch together enough data to build a decent home studio and keep Mrs. Kravitz next door off my back. Your links and incredible depth of explanations all over this forum (as well as others on the web) are targeting my unknowns like a Zeiss telephoto lens. Indeed a monster of information you are- thank you for your time out here. We readers (especially those of us who aint paid any real dues in this realm yet) are fortunate to be able to click here and get told cold.. These recent links have rendered my first post into dead weight taking up bandwidth, so away it went.. Thanks again, PD -> my project about to be underway: http://johnlsayers.com/phpBB2/viewtopic.php?t=1862

Thanks -Andrew gave the method for locating studs, etc - what I do is put strips of masking tape about an inch away from frames, before any paneling goes up - then I mark (with a Sharpie permanent marker) the location (and description - stud, RC, Screw, etc) of each and every component of the wall/ceiling/floor - After the first layer is up, I repeat for individual screw locations per layer (so you don't hit layer one's screws with those for layer two or three) - if you use the wide tape, you can get all this info on one (sometimes two) strips of tape PER wall intersection. It's critical that you get Studs perpendicular and RC level and straight (for runs longer than one stick) because you need to mark BOTH edges of the usable fastening surface so you can be sure you're fastening in the middle of that space. Every time you miss is another STC point lost... Under layers will only need half as many fasteners in each direction, this lessens any flanking into the cavity and saves on screws. The final layer will have a full schedule fastening, which goes through ALL layers and into the RC (or stud, if using full double framed walls) Also, when using a screw gun, first use some scraps of wallboard and framing and get your depth setting right before doing actual wallboard - you want to adjust the depth cone so that the screw just barely sinks below the surface - much more, and you'll tear the surface paper. This isn't good on ANY layer, it weakens the construction. On the surface layer it also makes things harder to get smooth for final taping. Gotta run for now, more later... Steve