Can I install polyiso continuous insulation over existing painted wood siding?
I am quoting a siding job on a small house on a lake in central New Hampshire, climate zone 6. They get a lot of weather and wind off of the lake. From the inside, the house currently has 1/2″ drywall, 2×6 stud framing (I believe it’s 16″ layout), fiberglass insulation (probably faced), 1/2″ OSB sheathing, WRB, and ship-lap or t&g wood siding installed vertically (I believe it’s pine) which is painted with latex. I would like to install at least 1″ of foil-faced polyiso foam board over the existing flat siding to act as an air, water, and vapor barrier. Then I would install a rain screen mesh or battens and wood siding, to be pre-finished or painted. The windows and doors would be retroactively flashed to the outside surface of the polyiso and then extended with tapered subsill and extension jambs. Does this scheme cause any problems?
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