Foam Board Roof Decking

Rigid foam board is just above the roof deck or an exterior insulation option.

Foam board roof decking. After installing several layers of rigid foam above the roof sheathing these workers installed plywood above the rigid foam. 1 4 spans flute widths up to 2 5 8 flexural strengths parallel lbs. The panels provide a continuous energy efficient surface. Unvented roofs with spray foam applied to the underside of the roof deck have been used since the mid 1990s.

1 4 dens deck roof board. The later is used in new construction as the interior board serves as an inner wall. It typically has 3 variations. The studs conduct more heat than the insulation between them.

The plywood was fastened through the rigid foam to the rafters with long screws. R values 28 tested in accordance with astm c518 spannings. Insulated foam sheets are also used as an insulated sheathing underlayment for exterior siding. 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.

Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. Install rigid insulation board in multiple layers with joints offset vertically and horizontally between adjacent layers. This type of insulated roof assembly limits thermal bridging through rafters. Polyiso consists of a uniform closed cell polyisocyanurate foam core and provides one of the highest r values per inch of any rigid insulation.

The snugness of the foam itself should be sufficient to hold the strips. This eliminates thermal bridging which is the energy lost through wall studs. Apply continuous air control membrane to existing roof sheathing or implement continuous air control at roof sheathing. Position the foam board between the rafters and push it upward until it fits snugly against the underside of the roof deck.

Bare foam board one sided sheathing board or double sided which is also reference as structural insulated panels.