Structural insulated panel

A structural insulated panel (or structural insulating panel), SIP, is a composite building material. It consists of an insulating layer of rigid core sandwiched between two layers of structural board. The board can be sheet metal, plywood, cement, magnesium oxide board (MgO) or oriented strand board (OSB) and the core either expanded polystyrene foam (EPS), extruded polystyrene foam (XPS), polyisocyanurate foam, polyurethane foam or composite honeycomb (HSC).

SIPs share the same structural properties as an I-beam or I-column. The rigid insulation core of the SIP acts as a web, while the sheathing fulfills the function of the flanges. SIPs combine several components of conventional building, such as studs and joists, insulation, vapor barrier and air barrier. They can be used for many different applications, such as exterior wall, roof, floor and foundation systems.

Although foam-core panels gained attention in the 1970s, the idea of using stress skinned panels for construction began in the 1930s. Research and testing of the technology was done primarily by Forest Products Laboratory (FPL) in Madison, Wisconsin as part of a U.S. Forest Service attempt to conserve forest resources. In 1937, a small stressed-skin house was constructed and garnered enough attention to bring in First Lady Eleanor Roosevelt to dedicate the house. In a testament to the durability of such panel structures, it has endured the severe Wisconsin climate and was used by University of Wisconsin–Madison as a day care center up until 1998 when it was removed to make way for a new Pharmacy School building. With the success of the stress skinned panels, it was suggested stronger skins could take all of the structural load and eliminate the frame altogether.

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