AP® Breathing Sheathing

Johns Manville AP Breathing Sheathing consists of a uniform closed-cell polyisocyanurate foam core bonded to a coated glass facer on both sides of the board. The semi-vapor-permeable design allows wall assemblies to dry to the exterior, making AP Breathing Sheathing a strong choice in climates and assemblies where vapor profile matters and a fully vapor-impermeable foil-faced board is not desired.

It provides the high R-per-inch of polyiso (R-6.0 at 1 inch) while delivering a continuous layer of exterior insulation that reduces thermal bridging. The board is produced with an EPA-compliant hydrocarbon blowing agent with zero ODP and low GWP, and is widely used in commercial wall assemblies tested to NFPA 285.