Re: Spray Foam versus Sheathing
filling between stud cavitys with foam is done but much more time consuming. however much less messy especially for around plumbing and electrical.
as for rafter bays the problem lies with creating "hot roof", meaning no air circulation underneath of the roof sheathing. there has to be through vents in the bay but its much harder to get a snug fit with the rigid foam so it stays put.. installing the through vents then spray foam is a better method.
with creating a "hot roof" two problems arise, the warrenty on roof shingles becomes void because they become baked. this does happen ive stripped several roofs which were done with 30 yr shingles that lasted merely 5 to 10 years. also with no air circulation the roof deck will rot
fire up the saw and make some dust