How Green are Structural Insulated Panels (SIPs)?

Posted on July 17, 2008
Tag(s): Green Building, Energy | | Email this

Structural insulated panels, or SIPs, are typically comprised of 2 sheets of OSB (oriented strand board) or plywood that sandwich a foam core, usually made of expanded polystyrene (EPS) or polyurethane. SIPs are great energy savers in new construction, saving significant amounts in home energy use.

Providing structure for walls, floors, ceilings and roofs, they go up quickly, saving labor costs, and provide a strong structure. Manufacturing of SIPs uses significantly less dimensional lumber and conserves timber resources. They create an airtight dwelling that is more comfortable and quieter than some other conventional forms of construction.

Polystyrene (EPS) panels average an R-value of 4-5 per inch of thickness. Standard thickness for wall panels is 3.5 -7.5″ and 5.5 -11.5″ for ceiling panels. Panels made with a polyurethane foam core have an R-value of R-6 to R-7 per inch of thickness. Wall panels are typically 3.5″ thick and ceiling panels are up to 7.5″ thick. According to the U.S. Department of Energy, “These panels, although more expensive, are more fire and water vapor-diffusion resistant than EPS. They also insulate 30%–40% better per given thickness.”

In an earlier post, I described the other differences between materials used for the inner core.