Question For Rod!

Rod, your book is amazing, I have found it very helpful with my build. I'm currently building a home with a basement studio and I have a quick question about the section in your book which covers adding mass to the existing floor above the room prior to insulation and adding a resilient channel ceiling with RSIC clips. It mentions in the book that the process would be to secure the drywall to the above floor with finishing nails, then calk and finish off with a 1X3 support when all the layers are up. It seems like it would be easier to just use drywall screws to secure it to the ceiling first as opposed to the finishing nails, is there a loss in isolation by doing this? Please let me know if you hae the time. Thanks, Jim.

anyone else have an opinion on this? would it be wrong to just fasten the drywall directly to the above floor section using drywall screws in the typical fashion and the caulk the edges?

I have the same question as you, and I know that I've encountered it in a few posts here. Unfortunately, I wasn't smart enough to document the answer or the post info. I'm pretty sure that his answer was "screws are okay, but I find using the nails easier." However, there is this post: http://www.johnlsayers.com/phpBB2/viewt ... highlight= Note the picture of the completed beef-up work, as well as Rod's "approval." Very clearly using screws. I don't want to put words in Rod's mouth though... Now, Rod can correct me if I'm wrong, but the goal of the beef up is to turn the existing floor/joists into one big leaf. So, all the surfaces are already touching together and are sealed by the backer rod and caulk. No air, no sound. However, piercing the layers of the drywall could potentially be seen as a space to allow air through. I would mud over the screw heads and would think that it would be sufficient. Any input? Please feel free to let me know if I'm wrong in this- I was about to screw a bunch of drywall in between my joists!

There is a reason Rod recommends what he does. Yes it would be simpler to just use drywall screws. I don't recall the exact reasons off the top of my head, but IIRC you want each sheet of drywall to be independent in terms of mass, as opposed to acting as one giant piece of mass, which is what would happen if you screwed them all together to the floor above. Double-check the book, I think Rod explains his reasoning there. Of course I could be wrong, I'm going from my (notoriously unreliable) memory here.... :wink:

one issue is the flex from the floor above. rigidly attaching the drywall (which has a different elasticity than the wood flooring and joists) could cause the screws to tear through the drywall. the cleats hold the drywall up without binding it (except via soft flexible caulk) so the floor can bend and even if the drywall is cracked due to flex its still has most of its integrity - side to side - and so the cleats should continue to work. if you have a lot of flex or nails cutting through the subfloor, using some celotex or blueboard on the underside of the floor before adding the drywall gives a bit more space for the floor to flex and should not create a significant 3rd leaf effect.