SIP FAQs and Common Questions


SIP stands for Structural Insulated Panel. An Insulspan® SIP consists of a core of molded expanded polystyrene (EPS) insulation or graphite-enhanced polystyrene (GPS) insulation with engineered oriented strand board (OSB) laminated to the top and bottom faces. When comparing Structural Panels there are three elements to consider:

  • The insulation (in our case the EPS insulation or GPS insulation)
  • The skins (OSB is standard for a reason but not everyone uses it)
  • The method for lamination (not all panels are laminated with the same adhesive or pressure)


Expanded polystyrene (EPS), the foam insulation inside our SIPS, has no food value and will not support the growth of insects, parasites, or animal, and plant life.

The best practices for keeping pests out of your home, no matter what it is made of, is to follow basic building codes. Learn more about pest control here Product Information Bulletin 205.

It depends on the width of the panel and whether you select a core of EPS insulation or GPS insulation. View our R-value chart, and read about how R-Values compare – initially, during construction and through the life of the building.  Explore R-values here.

EPS insulation and GPS insulation are inert, so they do not off-gas. These insulation materials do not contain harmful formaldehyde, unlike some other types of foam insulation. This also means that the EPS insulation will not change over time, or lose R-value, like some other types of foam, such as polyurethane.

Typically, plumbing does not go in an exterior wall since it might freeze.  Your interior walls will be standard stud walls, so you don’t need to worry about SIPs and plumbing.

Insulspan places wire chases inside the panels at 14″ and 44″ above the floor and 6″ from door openings on both sides for electrical outlets and light switches. Your electrician can place boxes anywhere along the wall. You can also specify custom chases, which we will pre-cut in the SIPs during manufacturing.

One of the benefits of building with SIPs is the continuous OSB sheathing. You can mount cabinets and install shelving anywhere along the wall. And, you don’t have to worry about finding a stud when hanging pictures! To find information about the size and quantity of screws to use to ensure the weight of whatever your hanging is properly support, please reference Technical Bulletin 126.

SIP structures are very efficient, and a very sustainable building method.

  • Insulspan SIPs produce much less waste at your construction site. With conventional stick framing, several dumpsters full of sawn-off construction materials are hauled to landfills.
  • OSB utilizes less wood pulp and is made from managed forests. Studies of SIP structures have shown that the total amount of wood used in an average SIP home is significantly less than that of a stick frame home.
  • Expanded polystyrene (EPS) is a lightweight insulation composed mostly of air. Only 2% of EPS insulation is plastic. Over the lifetime of a house, the EPS insulation used in SIPs will help reduce energy use, which results in a CO2 savings of many times the energy embodied in the petroleum used to make it.
  • It takes 24% less energy to produce EPS insulation than fiberglass insulation of equivalent R-value. Scrap EPS generated during the manufacturing process can be recycled into new EPS products.

Want to learn how you can reduce energy costs and gain the structural
strength of the Insulspan SIP system for your residential or commercial project?

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