[notfarnow]

Wow, thanks! Some great tips.

Because the roof is ~18 yrs old, and has had a few leaks, I'm going to pull everything off for sure. I expect to at least replace some boards; but if it's bad enough I've budgeted to lay new plywood over the whole roof.

As for insulation, the house is well insulated for a ~140 year old place. The soffits were not vented until this past fall. I'm sure that contributed to the roof's deterioration. When I was up in the attic above the bathroom, I could actually see condensation on the shingles' nails. I also noted some soft boards. I rented scaffolding and opened them up, put in the "rafter buddies" or whatever they're called. Venting the soffits eliminated the condensation issue, but I think a ridge vent would help too.

I'll post some more pics tonight, maybe seeing the actual roofing would be helpful