Materials appropriate for insulating sheathing with unvented cladding substrate include.
Rigid insulation roof over decking.
It is an acceptable practice to install a new roof over an existing roof membrane system provided that the roof deck is structurally sound and has been properly prepared to support the added load.
Attach to deck board.
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.
Specify this solution zip 8 39 mb.
Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls.
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After the roof deck is prepared the rigid foam boards need to be cut to size to fit snugly together on.
Rigid foam insulation installation prepare roof deck.
The bottom layer of a single ply membrane roofing system is the roof deck or substrate.
Nail it around the edges with roofing nails.
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.
Polyisocyanurate extruded polystyrene xps.
The insulation installed over the roof deck must be installed in multiple layers with joints offset in order to control convective looping at joints between insulation panels.
Steel deck with fully adhered single ply membrane over a cover board with xps insulation over gypsum board thermal barrier or applied directly to the metal roof deck.