The concept of caulking here is to ensure 2 things. The first being an air tight seal. So, if that means putting caulk on the entire frame before you put up the drywall, then do that. If you think you can guarantee a perfect seal by just doing the perimeter, then do that. The second point of caulk here is to fill any gaps to ensure the surface density is not compromised anywhere. Caulk has roughly twice the surface density that drywall has so as long as your caulk is at least half as thick as the drywall, you're good to go.Speaking of caulking, I spent a long time trying to sort out exactly how to deal with that and the drywalling. Read up a bunch in Rod’s book and searched here a ton. Just to make sure I’m not missing anything: I install the first layer of drywall and can caulk the whole perimeter of it, yes? Should I be mudding the first layer as well, or jut the second. I remembered reading that only the second was needed with proper caulking, but other posts suggest otherwise. Also, do I need to caulk on the back as well for the drywall (Rod says something about caulking the edges, but I didn’t quite get if that was the back or the perimeter)? Or is doing each layer of drywall on the perimeter (2 layers) and the underlay to frame enough?
The 32.93dB is the overall measurement. It's not for each frequency band. The drywall surface density the calculator uses is an average surface density for fire code drywall.The TL for the drywall says 32.93dB like you mentioned. You had said that was for 80Hz yes? The graph seems to be way lower at the 80Hz point and is a straight line up. Is there something I am missing? Also, fire code drywall is denser. Does it make much more of a difference?
Greg