What are Structural insulated panels (or structural insulating panels), SIPs, are a composite building material. 

SIPs share the same structural properties as an I-beam or I-column. The rigid insulation core of the SIP performs as a web. SIPs replace several components of conventional building such as studs and joists, insulation, vapor barrier and air barrier. As such they can be used for many different applications such as exterior wall, roof, floor and foundation systems.

 History

Although foam-core panels gained attention in the 1970s, the idea of using stress skinned panels for construction began in the 1930s. 

Thus in 1947, structural insulated panel development began with corrugated paperboard cores that were tested with various skin materials of plywood, tempered hardboard and treated paperboard. 

The majority of SIPs made today have OSB skins with EPS or XPS cores.

 Materials

SIPs are most commonly made of a foam core made of expanded polystyrene (EPS), extruded polystyrene (XPS) or rigid polyurethane foam, but other materials can be used. Some SIPs use fiber-cement or plywood for the panels, and agricultural fiber, such as wheat straw, for the core.

 Benefits 

The use of SIPs brings many benefits when compared to a conventional framed building. A well built home using SIPs will have a tighter building envelope and the walls will have a higher insulative value, which leads to fewer drafts and a decrease in operating costs for maintaining a comfortable interior environment for the occupants. Also, due to the standardized and all-in-one nature of SIPs construction time can be reduced over building a frame home as well as requiring fewer trades for system integration. The panels can be used as floor, wall, and roof, with the use of the panels as floors being of particular benefit when used above an uninsulated space below.

A SIPs system outperforms conventional stick framed construction structurally and maintains the versatility of the stick framed house when incorporating custom designs. Also, since SIPs work as framing, insulation, and exterior sheathing, and can come precut from the factory for the specific job, the exterior building envelope can be built quite quickly.

The rigid polyurethane foam insulation is a closed cell insulation as compared to fiberglass insulation which is an open cell insulation. Both insulations' R-values are tested in a laboratory under steady state conditions where there is no air infiltration. When a SIP is installed as a wall, foundation, floor or roof system, the rigid polyurethane foam is installed in a steady state environment, whereas fiberglass insulations are installed in a non-steady state environment because these wall, foundation, floor and roof systems have to be vented to remove moisture. Many research studies show that the R-values of fiberglass insulation decrease as the temperature differential of indoor and outdoor temperatures increase resulting in higher energy costs to the homeowner.

 Dimensions and characteristics

In the United States, SIPs tend to come in sizes from 4 feet to 24 feet in width. Smaller sections ease transportation and handling, but the use of the largest panel possible will create the best insulated building. Typical U.S. height for panels is eight or nine feet. Wall panels tend to come in  thicknesses US: 3.5–5.5 inches, but can be made up to US: 1 ft for roofs.

Rigid polyurethane foam  has an R-value (thermal resistance) of about 7 per inch of thickness, which would give the 3.5 inches of foam  an R value of 24.5. 

The air sealing features of SIP homes resulted in the Environmental Protection Agency's Energy Star program to establish an inspection protocol in lieu of the typically required blower door test to assess the home's air leakage. This serves to speed the process and save the builder/homeowner money.

For more information, contact us at info@sipsworldwide.com .