Rigid Insulation Roof Assembly

Code specifies the minimum r value of the rigid foam layer.

Rigid insulation roof assembly.

The insulation used in low slope roof assemblies typically falls into one of the four categories. Assuming rafter construction is it best to build them like walls rigid insulation outside breathe to inside or is it best to seal the rafters on the inside with taped rigid foam and let the assembly breath to the outside. Every one of them foil faced isocyanurate paper faced isocyanurate extruded polystyrene expanded polystyrene mineral wool aka stone wool rigid fiberglass. All atlas acfoam polyiso insulation boards are qualitymark certified providing consumers an easy way to identify premium products that meet or exceed building codes for the best in roof performance.

Gba blogs are filled with discussions of wall assemblies insulation vapor air barriers but i haven t found much on roof assemblies particularly cathedral types. There s a reason polyiso rigid foam insulation is used in more than 70 of commercial roof construction as well as in many residential builds. Dual purpose structural deck and insulating planks. Rigid foam also can be installed above the roof sheathing in tandem with air permeable insulation between the rafters.

There must be an air control layer air barrier under the rigid insulation boards. In this case the rigid foam can be thinner than when it s used alone. Lightweight insulating concrete lwic. Polyiso is an easy cost effective sustainable and energy efficient construction material.

The air control layer can be a fully adhered membrane on the roof deck or the air control layer. Or sprayed polyurethane foam spf. Owens corning foamular xps insulation is a closed cell moisture resistant rigid foam board ideal for many roofi ng applications including single ply protected roof membrane assemblies prma tapered vegetative roofs plaza decks architectural metal roofi ng and recover roofi ng.