I have an old 1890 era shingle style house with a finished 4th floor (cathedral ceiling, 8" rafters). As it's time to reroof, I'm getting estimates for putting insulation up - there is currently no insulation in the roof. I'm comparing 1) foam boards with R15 put in cavity at time of shingling, 2) open cell foam insulation (about R32) with an all roof ice & water barrier, and 3) closed cell foam insulation (up to R38+) with no barrier. I'm in a cold, wet climate.

My questions - are 2) and 3) preferable, despite the much greater cost? would 2) present a problem with vapor condensation?

And finally, what are your experiences, if you have insulated a similar home?