Structural Insulated Panels (SIP) Information

Structural insulated panels (SIP) are composite building materials, which are comprised of two layers of structural board with an insulating foam layer in between. The boards are often oriented strand board (OSB), and the foam is either polystyrene foam (EPS), extruded polystyrene foam (XPS), or polyurethane foam. Other materials may also be used including plywood, pressure-treated plywood, steel, aluminum, and cement panels. Exotic materials such as fiber-reinforced plastic, Magnesium Oxide, and stainless steel may also be used.  Structural insulated panels are also available with cores made from agricultural fibers, such as wheat straw, which provide similar thermal and structural performance as the foam.


SIPs are simple in design, with many advantages for walls and roofs. The insulation core acts as a web, while the structural boards perform as flanges across the panel – similar to I-beams. Structural insulated panels can be used in many different applications such as exterior wall, roof, and floor foundation systems. Their versatility replaces several components of conventional building including studs and joists, insulation, and vapor and air barriers.


Structural insulated panels are known to have excellent insulation capacity. SIPs provide better air tightness and practical thermal performance than conventionally framed walls. Being airtight allows very little infiltration, which adds to the thermal performance. Using SIPs may also significantly reduce heating and air conditioning costs. The air sealing features of SIP houses resulted in the United States Environmental Protection Agency’s (EPA) Energy Star program, which establishes an inspection protocol to assess the houses’ air leakage as a way to save the homeowner money.


An additional benefit of SIPs is the ease of assembly. Building with SIPs only requires basic carpentry, and makes it possible for houses to be under a roof within days. Structural insulated panels are highly resistant to wind damage, which makes them suitable for areas with high wind gradients or seismic codes.


Typically SIPs are custom made for the specific house or building, and are factory cut to size. In the United States, structural insulated panels come in sizes from 4 feet (1.22 m) to 24 feet (7.32 m) in width. In other places, dimensions are available in 300, 600, or 1200 mm wide and 2.4, 2.7, and 9 m long.