An open cell foam about 0 5 pound density is the most cost effective way to insulate but any opening over 1 16 could cause the foam to expand out onto the roof.
Spray foam underside of roof deck.
Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly.
Polyurethane or polystyrene spray foams can provide thorough coverage to roof rafters and attic walls in much less time than is needed for other materials.
University of florida researchers tested three levels of spray foam roof underside retrofit.
It s not coming from above the roof and it s not some new moisture source resulting from the spray foam.
It would be better to use a closed cell 2 pound density foam because it doesn t expand as much as open cell and is more likely to fill voids but not go through them.
How spray foam should be installed on the underside of the roof decking the unvented attic space is completely within the building s thermal envelope.
Where wood shingles or shakes.
Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls.
No interior class i vapor retarders e g plastic sheeting are installed on the ceiling side attic floor of the.
Lstiburek takes blame for bad language.
Moisture generated indoors or that infiltrates into the home is responsible for the bulk of the moisture in an attic insulated with spray foam on the underside of the roof sheathing.