1.   A more effective insulation is to box in the trap and drainpipe and fill the box with fiberglass insulation.

2.   A. The vapor barrier, usually kraft paper backing on fiberglass insulation, goes paper-side up, toward the rooms above.

3.   A. Yes, but use fiberglass insulation.

4.   After sealing the joints, wrap the ducts with foil-faced fiberglass insulation.

5.   Fiberglass insulation that has been soaked with roof water will be matted and stained.

6.   Fill it with unbacked fiberglass insulation and face it with sound-absorbing board, a common item sold at lumber stores.

7.   Fill it with unbacked fiberglass insulation, then attach sound-absorbing board to the studs.

8.   Fill the space with unbacked fiberglass insulation.

9.   Fill the space between the joists with fiberglass insulation, and screw sound-absorbing board on the bottom of the joists.

10.   For added protection, you can wrap the tape and pipe with non-flammable fiberglass insulation.