Foam Board Under Roof Deck

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.

Foam board under roof deck. Densdeck roof boards are fm tested and approved as the only 1 2 gypsum product to meet the. When installing a foil faced foam board insulation. An excellent fire barrier densdeck roof boards feature a noncombustible core and inorganic surface that offer greater fire protection than other conventional commercial roofing products when applied over combustible roof decks and steel decks. Vented attics that are insulated over the ceiling deck with increased amounts of blown fiberglass or blown cellulose.

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. In addition to installing the foam board on the underside of the roof deck you can attach it to the bottom edges of the. Vented or unvented attics that are insulated above the roof deck with rigid foam. It s not coming from above the roof and it s not some new moisture source resulting from the spray foam.

After installing several layers of rigid foam above the roof sheathing these workers installed plywood above the rigid foam. Lstiburek takes blame for bad language. It typically has 3 variations. The later is used in new construction as the interior board serves as an inner wall.

This type of insulated roof assembly limits thermal bridging through rafters. Unvented attics that are insulated on the underside of the roof deck with blown spray foam. Rigid foam board is just above the roof deck or an exterior insulation option. Densdeck stormx prime roof board this gypsum cover board is enhanced with a coated glass mat facer that achieves fm vsh approval rating with adhered 60 or 80 mil smooth back jm tpo membrane and standard jm tpo membrande adhesives when 4 x4 panels are adhered in low rise foam adhesive using the ribbon application with 12 o c.

Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. When installing rigid insulation in an attic to be finished as a living space you must provide a route by which hot air.