Vented versus unvented attic retrofit
I am considering having the fiberglass insulation removed from the attic floor and having open-cell foam sprayed in its place. Most foam installers are pushing the idea of sealing my ridge and soffit vents, spraying the underside of the roof and creating a so-called conditioned attic. This is a 2,100 square foot all brick ranch with a 6-12 roof built in 1967. We want to keep the insulation within the 2 X 6 framing as we have much of the attic floor covered with osb. We use it for some light storage. We’ve done tons of updating– new windows, doors, new high effeciency furnace/AC units which are in the basement. No ductwork is in the attic. I am getting a lot of conflicting information ( example: Demilac says to spray a vapor retardant paint on the foam; their installers say that they have never heard of this! One source says to tie the attic space into the heating/cooling system. Most say NOT to do this. One source says ice dams will be prevented by plenty of insulation AND ventilation. Another says unvented attics have no ice dams! )
Then there are health concerns over off-gassing, etc. Obviously, a vented attic would mitigate this somewhat. We are in Climate Zone 5 near Pittsburgh, PA.
Any help will be much appreciated. Thanks in advance! Rgn 2-27-10