Spray Foam Insulation On Roof Rafters

R value of 7 in 1 inch 97 closed cell foam.

Spray foam insulation on roof rafters.

The movement of air into indirect conditioning of an unvented attic is a slow gradual process that will not be noticeable by occupants and typically will not put any strain on the hvac system. It s not coming from above the roof and it s not some new moisture source resulting from the spray foam. 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. But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used.

Lstiburek takes blame for bad language. In an uninsulated attic the heat passes through roof sheathing and disperses into the attic space. The best attic insulation. All insulation materials require proper venting.

Heat from the house rises up to the attic but when there isn t one the heat rises up to the roof. When the choice is made to insulate along the underside of the roof deck spray foams have advantages over other insulation types because of the ability of spray foams to effectively air seal complex assemblies. Class i e 84 fire retardant meets building code spec. Use closed cell foam it green for attic rafters.

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. Because spray foam insulation applied to the underside of roof sheathing inhibits heat conduction. Rigid foam and spray foam are two of them.

Spray foam insulation that s convenient and easy to use. The spray foam can also serve as the thermal and vapor control layers in both new and retrofit construction.