I've got 2 pre-existing walls in my theater area that are were built out of 2x6s and I'm going to be putting a 2x4 wall in front of them to decouple. Do I fill both the 2x6 wall and 2x4 wall with insulation? If so, do I mix R19 and R13, or just use R13 in both?
Similar question for the ceiling - I have a new ceiling that is about 12" below the joists, and runs perpendicular to them. Do I fill the joists with R19 and use R13 between the new 2x4s, or is the R19 in the joists enough? Should the insulation be closer to the floor above or the bottom of the joists?