Spray Foam Under Roof Deck
Open cell spray polyurethane foam ocspf and closed cell spray polyurethane foam ccspf insulation sprayed to the underside of roof sheathing is a popular strategy for increasing roof insulation levels in all climate zones.
Spray foam under roof deck. You may have odor problems. The biggest weak point in my opinion is that if there is a roof leak you won t find out until the wood is rotted. Where wood shingles or shakes. It is not the end of the world.
Spf is not a greater risk under a roof deck than the risk associated with commercial compact flat roofs with multiple layers of insulation sandwiched between roof membranes and metal and wood structural decks. Spray foam under roof decks. Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. No interior class i vapor retarders e g plastic sheeting are installed on the ceiling side attic floor of the.
It s not coming from above the roof and it s not some new moisture source resulting from the spray foam. This construction approach was first used in the 1970s and it has been implemented much more widely since it was first included in the international code council s icc model building code in 2007 irc section 806 4. Just make sure you overdo your roof when the roof is installed. 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.
Your indoor air quality may get worse. I ve done a lot of work in energy efficient building and design. By encapsulating the attic and leaving the old insulation up there that filth is in your conditioned space. The spray foam definitely has its merits.
Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. 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. Lstiburek takes blame for bad language. Ready for something else.