Re: spray foam for crawl and roof
Again generally speaking ---- closed cell SPF products have basically the same performance.
Originally Posted by Fritz
Boy if you could go with SIPS go for it.
Our roof will be a project this year.
It is a cathedral with probably 6" joists also.
If we redo the sheathing, is spray in a good choice or SIPs?
And what Is the best idea for preventing ice dams on the roof?
We're on Long Island and just last week we had an ice dam that ripped off and twisted part of a gutter.
Otherwise --- you might consider SPF.
Also, apply a 2 inch thick layer of rigid foam on the exterior sheathing then add a second layer of sheathing to attach the roofing material to.
Basically ice damns are caused by warmth from the interior warming the underside of the roof. This melts any snow from the underside, the water runs down and freezes when exposed to the cold air.
To prevent this-- keep the warmth from inside from reaching the underside of the roof.
"" an ounce of perception -- a pound of obscure "