Polyisocyanurate insulation is a closed-cell rigid foam board manufactured with isocyanate and ployether mixed together in the presence of a catalyst that allows the molecules to rearrange, forming closed cells. Polisocyanurate (PIR) foam is similar in physical form to polyurethane but has improved insulating qualities. It has a wider operating temperature range that surpasses standard Styrofoam (blue board) and is fire and smoke resistant. PIR insulation is available in liquid (sprayed foam) and rigid foam board. PIR requires no thermal moisture barrier prior to installation.
R-Values (Resistance to Heat Flow) of polyisocyanurate will drop as some of the gas that has low thermal conductivity escapes and is replaced with air. This thermal drift occurs within the first two years after installation. An R-value of R-9 per inch will drop to an insulation value of R-7 and then remain unchanged unless the material is damaged. Typical R values of PIR insulation range from R-5.6 to R-8.
Also referred to as “blue board,” this Styrofoam product is a rigid insulation board used in foundations and for insulating exterior wall cavities. It is available in thicknesses of from ¾ inches to three inches. Blue board is manufactured by expanding polystyrene beads with steam and bonding the beads together under high pressure to produce a rigid board. Blue board is available in sizes of 4×8 feet, 4×9 feet and 4×10 feet. Other lengths and widths are available by special request. Styrofoam insulation requires the installation of a thermal barrier (6mm plastic sheeting) prior to installation to protect the material from moisture penetration.