The most popular materials for manufacturing rigid foam insulation panels are polyisocyanurate, extruded polystyrene and expanded polystyrene. Regardless of the material used in their construction, rigid foam insulation panels have several advantages over traditional batt or air-blown insulation. Rigid foam installs more easily and provides a more effective air barrier.
All types of rigid foam panel insulation are friction-fitted, meaning installers wedge them into place between wall studs or floor joists. Because panels wedge in between joists and studs more firmly than batt or fill insulation, they provide a true air-tight barrier. Also, because of their stiff structure, foam panels do not become dislodged as easily as traditional insulation materials. However, even the cheapest type of rigid foam panels are more expensive than traditional insulation.
Polyisocyanurate is the most efficient type of foam panel insulation, preventing the most energy loss of the three types. Polyisocyanurate panels typically come sealed with foil tape on either side, making them an effective radiant barrier in certain applications. Because of their high efficiency, polyisocyanurate panels are also the most expensive type of rigid foam insulation.
Expanded polystyrene is the cheapest and least efficient type of foam panel insulation, and it takes up the most space. Extruded polystyrene offers both performance and cost between that of expanded polystyrene and polyisocyanurate. Unlike polyisocyanurate, both types of polystyrene are preferable in damp conditions, as neither type readily absorbs water.