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
Posted Sat, 02/27/2010 - 21:11
Edited Sun, 02/28/2010 - 06:14
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