Insulation s r value is a measure of its effectiveness and a single 1 inch sheet of polyurethane foam gives you an r value of 5 5 to 6 5 according to the u s.
Rigid insulation in wall cavity.
In regard to the range of cavity wall insulation options the mac design guide for taller masonry cavity walls says a foil faced polyisocyanurate insulation is the most beneficial iso is known for its use as roofing insulation but it is also recommended in masonry cavity walls for its thermal moisture and fire performance as well as.
After that thin furring strips are installed on top of the foam to provide a firm base for the drywall screws and drywall but can you run rigid foam between the studs just as you would do with fiberglass rolls or spray foam.
These products offer superior long term thermal efficiency fire resistance moisture control acoustic performance and are compatible with numerous framing systems and cladding attachment systems.
Extruded polystyrene xps rigid foam insulation available foam sealed designed for masonry cavity wall applications foamular cw25 extruded polystyrene xps insulation is virtually impervious to moisture along with its high r value light weight competitive price and wide range of sizes makes it ideal for use in a cavity wall system.
Cavityrock is a semi rigid insulation board designed for exterior cavity wall and rainscreen applications.