Originally printed in Cottage Magazine, April 2013, written by Jerry Eberts
Building With Structural Insulated Panels (SIPS), Prefabrication, labour savings and high insulating values are just a few of the many advantages to this increasingly popular building method.
Imagine if there was a simpler, stronger way to build a cottage, a method that cut construction time in half – or more- and resulted in a significantly more energy-efficient building than traditional stud-frame construction. If such a method existed, wouldn’t any builder be keen to try it?
Consider this: structural insulated panels – better known as SIPs- deliver all this and more.
SIPs have been in use for more than 60 years and continue to gain momentum with builders and homeowners alike. Initial material costs are slightly higher than with stick-built structures, but a SIP home can be put up in a matter of days – even hours – and the costs are offset by startlingly lower long-term heating and cooling costs.
WHAT IS A SIP? A structural insulated panel is a sandwich made up of a core of expanded polystyrene foam between two pieces or oriented strand board (OSB). Normal thickness for the OSB is 7/16 inch, but 5/8 inch is often used for flooring. The boards are bonded to the foam core with waterproof urethane glue. The finished panel is strong, reliable and, as noted, extremely energy-efficient.
The top and bottom of wall panels have 1 1/2 inch voids to allow them to be anchored to standard 2×6 dimensional lumber sole and top plates (the latter inserted after the wall panels are raised). Roof SIPS, trusses or second-storey floor joists can then rest on the top plate. SIPs are joined together vertically by narrow SIP spline blocks that fit into recesses on the edge of each panel. The spline blocks are constructed in the same way as the SIPs themselves, with a foam core. Panels are joined together using SIP screws, designed to go through one panel and into the next panel to a depth of at least 1 1/2 inches.
Structural insulated panels are available in widths of four and eight feet and from eight feet to 24 feet in height and, once assembled there are practically no seams. There is nearly total elimination of studs during assembly. SIPs can replace conventional walls in just about any structure designed for stick-frame construction. Rake walls (gables) and rounded windows are easy to cut and shape. The panels can also be used for roofs and floors.
Structural strength of a SIP wall is better than for a conventional stick-build. In fact, the vertical axial loading capacity of a SIP wall is more than 4,000 pounds per lineal foot – all without using studs, though extra reinforcing is required around widow and door openings.
A handy homeowner can install his or her own panels, but the assistance of a carpenter experienced with SIPs might be a good idea the first time out.
- Insulating and Moisture
- SIPS and Timber Framing
- Earthquake Resistance
- Fire Resistance
- Bug Resistance
- Electrical Runs
- Energy Efficiency
- Environmental Advantages