The new American Dream: 100K(+ 20) | Starter Home

About: SIPs by nataliemikosz
September 3, 2008, 3:37 pm
Filed under: Material/Building Systems | Tags: , ,

Structural Insulated Panels, or SIPs, are a composite building material. They consist of a sandwich of two layers of structural board with an insulating layer of foam in between. The board is usually oriented strand board (OSB) and the foam either expanded polystyrene foam (EPS), extruded polystyrene foam (XPS) or polyeurethane foam.

SIPs share the same structural properties as an I-beam or I-column. The rigid insulation core of the SIP performs as a web, while the OSB sheathing exhibits the same properties as the flanges. 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.

The use of SIPs brings many benefits and some drawbacks 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.

An OSB skinned system structurally outperforms conventional stick framed construction in some cases; primarily in axial load strength. SIPs maintain similar versatility to stick framed houses 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 EPS 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 EPS 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. EPS foam is a non-toxic hydrocarbon. Burning it results only in water vapor, carbon dioxide and trace levels of ash, similar to paper. (

R-Control SIPs have a production and sales facility in Waukegan, IL; which may appeal to anyone who will be siting their project in the Chicagoland area, since the SIPs are prefabricated and require shipping. I am currently awaiting pricing information.

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