i have a cold attic space that has an interior wall into my living space. What should i have for insulation? I can only access the attic/cold side of the wall. Also, would i use a vapor barrier?
Vapor barrier, if any, on the warm side of the insulation.
Type of insulation is your choice. More is better, within reason. Costs vary - if you have space for it, cellulose is usually the best bang for the buck. The insulations that perform better in thinner sections also cost more per applied R-value. With a wall application, cellulose would need a net, or a second (non-structural) wall to hold it in place.