Structural Insulated Panel

A structural insulated panel, abbreviated SIP, is a prefabricated building panel made of a rigid foam insulation core, typically expanded or extruded polystyrene or polyurethane, sandwiched between and bonded to two structural facings, most commonly oriented strand board, so that the assembly acts as both the structural wall or roof element and its insulation in a single factory-made component. Developed from experiments with stressed-skin timber panels in the mid-twentieth century and commercialized more widely from the 1980s onward, SIPs are erected rapidly on site compared with conventional stick-built framing and insulation, and their continuous foam core reduces the thermal bridging that occurs at the repeated wood studs of conventional framed walls, giving a SIP-built structure notably better energy performance for a comparable wall thickness.