Hello and thank you in advance for anyone who answers this question. I’m one of the many poor souls who has found themselves with a 1970s cape that needs some help. I’m located in zone 5, southern NH.

The house has 2×4 exterior walls with no insulation and 2×6 rafters with R11 fiberglass insulation stapled to the rafters with a 2″ airgap between the roof deck. The triangle attic is only insulated above the drywall, again with R11. The roof has gable vents, no soffit venting. The sheathing and roof deck are barn board with plenty of gaps between planks so this place leaks air like crazy.

We are doing a total renovation starting with the exterior and my question is what is the right way to insulate this place. We are re-siding and replacing the old windows in phase one. 

Then we are gutting down to the studs on the interior. 

In a few years we are going to gut the upstairs, put a full shed dormer on the back (I know it’s expensive, but we have a family friend who is a framer), and will be reroofing. 

From what I’ve read exterior insulation is best, but what should I be doing on the inside? I’ve had contractors recommend closed cell spray foam in the stud bays and 1 inch rigid foam on the outside.

This house is lightly framed so I don’t have much to work with. If I am able to put foam on the roof, should I be trying to vent the attic, or go for an unvented space?