Structural insulated panels (SIPs) are a building material that sandwiches a thick polystyrene foam between two rigid boards (oriented strand board, or OSB). This creates a strong, lightweight, and very energy-efficient product that essentially combines the framing material with the insulation. This eliminates the thermal gap between the exterior and interior wood frame and creates a very tight envelope with a high R-value rating.
SIPs can be be used for most structural parts of a home’s envelope—roof, walls, and even floors. They go up fast—a good crew with a good plan can frame all the exterior walls of one floor of an average-sized house in a day. The panels are strong, too—up to three times stronger than a conventional framed house.
An Italianate Dream SIP Walls
An Italianate Dream SIP Walls and Roof
An Italianate Dream SIP Finished
While SIPs are typically used for new builds, they can also be a good technique for a remodel as well. Due to their structural rigidity, and their ability to be used as floors, walls, or roof planes, SIPs can make an exceptionally air-tight wing on a house that acts as a unit. SIPs also create very rigid and energy-efficient floors, which make them a cost-effective choice for a quality addition without a continuous foundation. Here are some photos of SIPs being used in remodeling situation
First Floor SIP Addition
Second Floor SIP Addition
SIP Floor and SIP Walls
SIP Addition Before Roof
Setting a Roof Panel
Finished SIP Addition
When SIPs are used as roof structures, the roof then becomes part of the insulated envelope, and the attic becomes living space. That can have a big impact on usable square footage for a home, adding up to 3/4 of the total footprint of the house in conditioned bonus space. Best of all, as soon as the windows and doors are installed, the house is already insulated and ready to hold the heat, better than most houses. That can make a big difference for cold-weather construction.
First Roof Panel
Last Roof Panel
The Finished Attic Space
Overall, while more expensive, SIPs do have some advantages over frame construction. They are highly energy efficient structures with greater structural rigidity. The have been in use for over 70 years, and can make a long-lasting home that will be very comfortable. Where budget allows, this can be an excellent green building technology to consider, and in some situations, this can even be the most cost-effective way to proceed.