Foam Board Under Roof Deck

Unvented attics that are insulated on the underside of the roof deck with blown spray foam.

Foam board under roof deck.

Densdeck roof boards are fm tested and approved as the only 1 2 gypsum product to meet the. 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. High efficiency attic insulation helps provide added thermal protection lessens wasted energy and increases enhanced comfort and quiet. Bare foam board one sided sheathing board or double sided which is also reference as structural insulated panels.

This type of insulated roof assembly limits thermal bridging through rafters. Lstiburek takes blame for bad language. The later is used in new construction as the interior board serves as an inner wall. 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.

When installing rigid insulation in an attic to be finished as a living space you must provide a route by which hot air. Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. It s not coming from above the roof and it s not some new moisture source resulting from the spray foam. Vented attics that are insulated over the ceiling deck with increased amounts of blown fiberglass or blown cellulose.

Rigid foam board is just above the roof deck or an exterior insulation option. Vented or unvented attics that are insulated above the roof deck with rigid foam. The plywood was fastened through the rigid foam to the rafters with long screws. In addition to installing the foam board on the underside of the roof deck you can attach it to the bottom edges of the.

After installing several layers of rigid foam above the roof sheathing these workers installed plywood above the rigid foam. When installing a foil faced foam board insulation.