Rigid insulation revisited/ residential shingle is

I don't know if I should start a new topic or just continue it in here, so I will move it if asked...it refers to the recent discussions regarding installing asphalt shingles directly over sheathing that is either adhered to polyiso foam, or a foam in pl>>>

Timberpeg, Rockport, New England Timberframe, and a couple of hybrid pine/spruce/ hemlock mutts. Green oak is a real challenge, but a sturdy structure. I have made it a point lately to put together timber frame buyers with old barn owners looking to se>>>

I don't think foam is a problem with tile/slate/metal and maybe even concrete, but the heat retention is what eats up shingles. Fast.

Builderr, you can ignore my question in the other thread. Who's timberframes did you do, or did you do your own? We>>>

just my 2 cents worth on spayed in place insulation. I am seeing problems when the foam expands, will push out in the cracks in the roof boards, dislodge slates(old houses with steel nails, they will break) pushing up the lead flashings around pipes, etc.>>>

That can be a problem alright! Suposedly, as long as the insulation is closed celled and the moisture can't wick through it is alright. I like to vent my roofs so I can control the moisture instead of stoppig it. It has to go somewhere! I have a tile>>>