CertainTeed's FlintBoard® ISO is a high-performing, workhorse insulation board for low-slope roofing applications. FlintBoard® roof insulation slows the flow of heat into and out of the building through the roof deck, reducing energy costs for building owners as well as thermal strain to the roof system. Composed of a closed-cell polyisocyanurate foam core, FlintBoard® offers the highest R-value (resistance to heat flow) per inch available and long-term thermal resistance values (LTTR*) from 5.7 to 27, LTTR. FlintBoard® ISO is available in multiple thicknesses ranging from 1" to 4.5", in 4' x 4' or 4'x 8' panels, and can be installed in multiple layers, meeting any R-value project specifications. FlintBoard® ISO is faced on top and bottom surfaces with organic fiber-reinforced felt, compatible with several insulation adhesives. FlintBoard® may also be mechanically attached. FlintBoard® ISO is designed to be easy to install, with a lightweight...See More, rigid construction that makes it simple to handle and position on the roof. FlintBoard® ISO is marked on one side for use with hot-applied systems and is unmarked on the opposite side for use with single-ply systems. FlintBoard® ISO is primarily manufactured with a 20-psi formulate and is also available in 25-psi. This versatile insulation product is engineered for use with built-up and modified asphalt roof systems, single-ply systems and coal tar. Reach out to your local CertainTeed Territory Manager to request a sample and demonstration of FlintBoard® ISO. *LTTR is the industry standard method for calculating the 15-year time-weighted average for roof insulation. See Less