When spray foam is installed on the underside of the roof deck the attic space is insulated from heat that otherwise would be entering the attic.
Spray foam underside of roof in attic.
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.
Attic ceiling to stop airborne moisture from reaching a cold surface and condensing inside the building envelope.
In this design insulation effectively separates the interior and exterior spaces while slowing down moisture flow so the dewpoint is not achieved within the building envelope.
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Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls.
Insulating and providing airtightness with spray foam at the underside of the roof as part of an unvented attic assembly will elevate such concerns.
It s not coming from above the roof and it s not some new moisture source resulting from the spray foam.
Unvented attics rely on an air impermeable insulation installed to the roof deck s underside i e.
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.
Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly.