Rigid Insulation On Top Of Roof Deck

Densdeck roof boards are fm tested and approved as the only 1 2 gypsum product to meet the.

Rigid insulation on top of roof deck.

They often simplify insulation and air sealing details versus conventional insulation on the floor of the attic that may be compromised by numerous penetrations from recessed lighting fans equipment and ductwork. Install nailbase for cladding. Building air tightness would now preside at the top of the building enclosure at the roof deck and attic walls gables. Install roofing underlayment flashing and cladding as per best practices.

The panels need to fit together tightly to help prevent warm air from leaving the top of the building. Most types of rigid foam insulation have a higher r value per inch than fiberglass batts. Attach to deck board. Many homes in more urban areas or other places with dense populations are opting for this method because they can better optimize space.

Polystyrene foam and foil faced polyisocyanurate foam. Foamular xps insulation products 404 604 404rb and 604rb are used in prma applications. The 6 inches of rigid insulation added to the top of the existing roof deck needed to be done in a manner that was invisible. The trim the frieze boards the fascia and the overhangs all had to look like they belonged.

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. Installing rigid foam insulation on top of roof sheathing is a great option for commercial buildings and homes with limited space. Rigid insulation layers exterior to existing roof sheathing must provide sufficient thermal insulation r value to control condensation risk see climate specific guidance. Rigid foam is produced in various size panels 4 ft x 8 ft 4ft x 4ft etc.

The purpose of the requirement that rigid foam installed above roof sheathing meet certain minimum r values is to ensure that the roof sheathing stays warm enough during the winter to avoid moisture accumulation and possible sheathing rot. Foamular xps insulation is the only insulation used in prma roof systems due to its excellent resistance to water absorption compared to any other type of rigid board insulation. Nailbase must be vented in high snow load areas. Installing stacks of rigid foam between rafters is slow fussy work but it might make sense for a do it yourselfer.

Both install in the same manner but the foil faced product offers slightly more r value. Rigid foam insulation is available in two main types.