Foam Insulation On Roof Sheathing

3 benefits of rigid foam sheathing.

Foam insulation on roof sheathing. There are lots of different ways to insulate this type of roof but one of the best methods calls for the installation of rigid foam insulation above the roof sheathing. There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing. Open cell spray foam insulation is risky in all climate zones we already know open cell spray foam is risky in cold climates. Plywood has an r value of 1 25 and fiberglass batts have an r value of 3 14.

Open or closed cell spray foam is applied to the underside of the roof sheathing and additional fiberglass or cellulose insulation is blown in as a cost saving method for meeting high insulation requirements and filling in the cavity space between the rafters to the ceiling deck. Featuring integrated moisture air and thermal protection zip system r sheathing completely reimagines traditional wall assemblies by streamlining exterior water air and thermal management. There have been isolated moisture related incidents that raise potential concerns about the overall hygrothermal performance of these systems. Johns manville r panel rigid roof insulation board offers r values of up to r 23 6 providing high thermal efficiency.

R 7 5 scored squared edge rigid foam board insulation sheathing. Insulated roof assemblies can be vented or unvented. Unvented roof strategies with open cell and closed cell spray polyurethane foam insulation sprayed to the underside of roof sheathing have been used since the mid 1990 s to provide durable and efficient building enclosures. Owens corning foamular 150 1 1 2 in.

R panel is manufactured with a closed cell polyisocyanurate foam core bonded to fiberglass reinforced facers and designed for use over metal nailable and non nailable roof decks with a variety of membrane systems. 12 15 moisture content or less before installing cavity insulation. If installing closed cell spray foam or other low permeance insulation to the interior it is very important to verify that the roof sheathing and framing are dry e g. Both papers basically came to the same conclusion.

More effective insulation with r values ranging from 3 6 to 8 0 rigid foam sheathing has much better insulation per inch than other materials i e.