Rigid Insulation Board
Rigid insulation board (Figure 3-5) is a rigid or semirigid synthetic product commonly referred to as structural insulating boards (SIP)
Figure 3-5 Rigid insulation board.
Or panels, rigid boards, foam insulation boards, rigid foam insulations, slab insulation, or sheathing boards. They are produced under a wide variety of trade names. Rigid insulation boards or panels are commonly manufactured in 2′ X 4′, 4′ X 4′, and
4 ‘ X 8’ sheet sizes with thicknesses of V2", 3/4", and 1" nonlaminated and laminates of V2", 1", and 2". All edges are butted. Rigid insulation boards are available faced or unfaced. Reflective facings function as vapor retarders.
Rigid insulation board is flammable and must be covered with a fire-resistant material, such as gypsum wall board, when it is installed on interior walls.
Some rigid insulation board is produced specifically for use on interior walls. This type is commonly made from wood or cane fibers with one side prefinished. Rigid insulation board designed for use as structural insulation is produced from compressed fibrous materials other than wood and does not have a prefinished surface. Rigid board panels made from polyurethane, polystyrene, polyisocyanurate, and phenolic are commonly used for exterior wall sheathing in new construction and to insulate basement and crawl space walls. Some R-values for common type of rigid insulation board are listed in Table 3-3.
Rigid board insulation has a high R-value and can be used in areas where space is limited, but it is also has a higher cost per inch than other insulating materials.
Rigid insulation board must be installed with tightly butted edges. Fill gaps of Vie inch or greater with pieces of insulation
Table 3-3 Some Rigid Insulation Board R-Values
Board cut to fit. Do not fill a gap between boards with other noninsulatng materials or any type of adhesive.