Structural Insulated Panels (SIPs) have some real advantages for building energy efficient houses. If you haven’t looked in to using them recently it may be well worth your time to do so.
A SIP is an engineered panel that can be used to create exterior walls and roofs and is made up of a high-density foam core sandwiched between two pieces of oriented strand board. Dimensional lumber is used at the panel edges to provide a solid means to attach panels together. The panels are made with high-tech machinery that assures quality control. Raceways for electrical wiring are cut during manufacture, and window and door openings are already provided. The panels go together and make a complete structural wall or roof and do not need much on-site adjustment. Panels are hauled directly from the factory for setup at the job site.
There are three main reasons contractors are using SIPs. We’ll look at them one at a time.
First, SIP construction is very energy efficient. Not only is the high-density foam a good insulator, but thermal bridging is greatly reduced. In ordinary construction with studs 16” on center thermal bridging occurs every 16 inches and about 23% of the traditional wall is taken up by wood thermal bridges. With SIPs, bridging only occurs at the panel joints which are ordinarily spaced at least 4’ apart. Also when installed correctly SIPs allow very little air leakage. SIP houses have been tested to less than 1 ACH at 50 Pascals.
Second, SIPs can make the exterior framing go much faster. Since all the panels are ready to install as they come off the truck it is only necessary to caulk the joints, fasten them together and tape the seams and the wall is complete. Holes are drilled through the bottom plate at the location where the wiring raceway is located in the panel.
Third, because the panels are made in a factory under ideal conditions the assembled product exhibits quality and strength difficult to obtain with field cut and assembled materials. The Oriented Strand Board skins create a very rigid strong wall.
SIPs require different construction techniques than traditional methods so it is important for everyone on the assembly crew to understand and use installation details the manufacturer provides as well as to make sure other trades involved in the project understand the unique characteristics so they don’t inadvertently do something that damages the panels.
So next time a client wants a quality house with a new flavor of efficient construction, perhaps offer them a SIP.