Spray Foam Under Roof Sheathing

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Spray foam under roof sheathing.

The anecdotes and data are enough to provide a few rules of thumb for designers and builders who want to install spray foam on the underside of roof sheathing. Spray foaming under roof sheathing i need to do something with my house but could use a few answers from someone experienced. Increasingly building scientists are investigating why osb roof sheathing on many spray foam insulated roofs stays damp for months at a time. Underside of roof decks since the late 60s early 70s and to my knowledge i have not seen or heard of a rotted substrate under and conditions closed cell foam was applied.

Install spray foam insulation along the underside of the roof deck to create an insulated unvented attic which can provide a conditioned space for hvac equipment that is located in the attic. 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. Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. Spray foam on underside of roof sheathing.

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. Our house was built in 1904 and the square footage of the attic floor is about 1100. Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. Open cell spray polyurethane foam or closed cell spray polyurethane foam ccspf insulation can be sprayed along the underside of the roof sheathing to provide a conditioned and insulated attic space that can be durable and efficient in all climate zones see figure 1.

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.