The spray foam definitely has its merits.
Spray foam under roof deck.
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.
You may have odor problems.
Ready for something else.
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.
It s not coming from above the roof and it s not some new moisture source resulting from the spray foam.
It is not the end of the world.
Lstiburek takes blame for bad language.
No interior class i vapor retarders e g plastic sheeting are installed on the ceiling side attic floor of the.
I ve done a lot of work in energy efficient building and design.
Just make sure you overdo your roof when the roof is installed.
Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly.
Spray foam under roof decks.
Spf is not a greater risk under a roof deck than the risk associated with sips.
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.
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.
Your indoor air quality may get worse.
By encapsulating the attic and leaving the old insulation up there that filth is in your conditioned space.
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.