All- I apologize in advance for this messages' length, but there are several issues I need clarification on (I've read opposing views on each topic, and haven't been able to find reasonable resolutions). That said, on with the show. About the house: Single story contemporary, built in the early 70's above a dirt crawlspace (about 3 1/2 - 4 feet from floor to 'ceiling'). The crawlspace floor has a vapor barrier, is mostly (80%-90%) under ground-level, and resides under the entire house. The crawlspace is vented though foundation vents. Originally, I figured this a Bad Thing, and intended to cover these vents especially in the winter. This changed when I realized the furnace collects its combustion oxygen from this space. I'm considering changing this, but this is for a later discussion. The ceilings are all cathedral-style: very little room for insulation. The small attic there is has R-19 foil-backed fiberglass batts along the walls and linving-space ceilings. Ok.. 1) Does it make sense to insulate (and how much to insulate) the crawlspace walls? 2) How much insulation should be on the 'ceiling' of the crawlspace (Zone 2/3 on the heating maps)? With the vapor barrier on the floor, does the ceiling also need a barrier? The insulation there now is paper-backed fiberglass -- which way should the paper be facing? Towards the living space, or towards the ground? 3) What are peoples recommendations for improving upon wall insulation? a) We're planning to reside the house -- what benifits does the Tyvek wrap provide? b) In the residing process, what are our options for adding insulation? Does the foam wallboard make the most sense? How well does the polyisocyanurate work in walls (is this an appropriate application of it?)? 4) Looking to the future, we're also thinking of improvements to the roof. My initial thought was to remove the shingles, and lay foam boards on the exisiting plywood, then installing a second "false roof" on top to fasten the shingles. Would this improve the envelope significantly to make it worth it? I think that should do it for now. Thanks for your thoughts!
