Attic insulation product choices

[charlesg]

I am finishing the attic to increase my living space. I also want adequate insulation up there. I know, behing in the northeast, I should get atlease R38 between the rafters of the roof but since the roof was built with 2x6, it does not leave me much space.

I could increase the space by furring out the rafters 2 to 4 inches but that would limit my space too much in certain key areas.

I know most of the time, people use fiberglass bats and they staple it between the rafters but is there a good reason why I could NOT use something like THERMAX polyisocyanurate pannels. A 4" sheets (leaving me a good 1 1/2" of air gap) would get an R-value or 25 or 28. Significantly more than the R15 I could get with high density fiberglass batts.

Any ideas?

[grumpydasmurf]

What ever you use MAKE SURE you leave some kind of space for air flow between the rafters.

You could place a recovery board or polyiso foam insulation on the roof deck. To do this you would need to remove the shingles and install the insulation and install new shingles. If you install the polyiso insulation you will need to put plywood ontop for a nailing base.