Definition

A Structural Insulated Panel (SIP) is a high performance building system used mostly for residential and light commercial construction. The panels are manufactured under factory controlled conditions in modular sections according to the design specifications. Some manufacturers also provide a ready-to-use paneling system, with openings cut, and the doors and windows installed in the factory. The panels are then transported to the project site, where cranes lift and install each SIP into the correct location.

This system uses an insulated foam core sandwiched by structural panels. Generally, SIP is made of a sandwich consisting of one layer of encapsulated polystyrene (EPS) board between two layers of plywood or Oriented Strand Board (OSB) (Fig. 3.9). However, alternative materials can also be used for both the core and structural skin (Table 1). Cement-board and fiberglass may be used for the structural skin. Normally, gypsum board or other fire-rated material are applied on the inside to minimize the spread of fire. Polyurethane and polyisocyanurate rigid foam can also be used for the insulating material, however they tend to be more expensive due to their better insulation performance, moisture protection, and fire resistance.

Special attention is required for SIP installation. The main advantage of SIP panels is the airtight envelope they create, therefore, the panels must be carefully placed together. Dimensional lumber is normally used for the connection (Fig.3.10), however it produces thermal bridging and decreases the insulation value. A common practice is to use an insulating material, such as insulated lumber or composite splines (Fig. 3.11). Expanded foam, sealing tape, sealing mastic, and nails are also used for SIP connections.