Originally Posted by clausdk
In all cases there is a solid wall made of light concrete, sort of cinderblock type.
Studs to form the airgap of X size/depth + clips/channels + 2 x drywall/GG
Same as above but smaller airgap and 3 x drywall.
Studs of a given size/depth with 2-3 drywall directly onto it and GG - the studs would obviously not touch the inner wall.
And in general, how much effect does the airgap have in general.
When using clip and channel, you have an air gap, you don't need to add another one. When doing 3layers of drywall with an air gap, you then dont need the channel because the 2walls are already not "connected". Unless you have a complete room within a room, you should use channels where you only have 1 wall. Like on your ceiling.
I have never seen any data on a double wall with resilient channel on them. When you have a air gap between 2walls you don't use resilient channel.
A, When you say stud to form air gap, you mean the studs are not filled with fiberglass and is separated from you cinder block? If you use resilient channels, fille the cavity with fiber glass or rockwool, don't leave air gap.
B, you have to make sure that the spacing is correct to support all the weight of the drywall, 3layers is heavy. Don't put airgap between the students and the cinder block if you use resilient channel. Fille the students with fiberglass or rockwool
C airgap of 1" fill the stud with fiberglass or rockwool. Use use isolating clips to decouple the wall (like ib-3 for example) 2layers will give you a good stc. A third layer will help but the return on investment is not that much. You will get better bass isolation as your wall get heavier. Some will say you third layer drywall more or less equal 2layer with Gg
How does an air gap impact the isolation
Here's an example
(all have fiberglass filled stud, 5/8" type x drywall)
Dd + stud + dd : stc36
Dd +resilient + stud + dd : stc 54
Dd + resilient + stud + resilient + dd : stc60
Dd + stud + airgap 1" + stud + dd : 69
The airgap is having a good effect on pretty much all frequencies , including the lower frequencies.
I hope this helps