Foam Board Roof Decking

Attach to deck board.

Foam board roof decking.

Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. Attach the tongue and groove insulation boards to the concrete wall with adhesive. 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. Foam on the underside of the roof deck would provide a more reliable air seal but has long term issues related to roof rot since the unvented roof deck would get a lot of.

Note that table r806 4 indicates the amount of insulation above the roof deck or air impermeable insulation below the roof deck required for condensation control assuming minimum required total insulation as indicated in section n1102 building thermal envelope. R values 28 tested in accordance with astm c518 spannings. Given that it seems that the ideal roof deck build up would consist of. Johns manville r panel rigid roof insulation board offers r values of up to r 23 6 providing high thermal efficiency.

Rigid roof insulation board. 1 4 dens deck roof board. Frothpaks or 5 for 1 part foam cans. For a basement remodeling project consider insulating basement walls with foam board.

Use a premade kit for this type of project. At 600 board feet you can get the spray foam cost down to about 1 20 board foot compared to 3 35 bf ft in the 12 b f. The panels need to fit together tightly to help prevent warm air from leaving the top of the building. For new construction use rigid boards to insulate slabs and the outside of foundation walls.

This section outlines the conditions for unvented attic roof assemblies. Position the foam board between the rafters and push it upward until it fits snugly against the underside of the 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. Composed of a closed cell polyisocyanurate foam core bonded in the foaming process to retroplus roof board on one side and a glass reinforced facer on the other.

After the roof deck is prepared the rigid foam boards need to be cut to size to fit snugly together on your roof. Top surface is sealed with this special coating to reduce excessive asphalt absorption in hot asphalt applied roofing systems. I m planning on open cell spray foam on the underside of the roof deck. I am curious as to whether the first layer of osb could be omitted if the foam board did not react to.

Rigid foam is produced in various size panels 4 ft x 8 ft 4ft x 4ft etc.