There are many types of prefabricated structured insulated panels (SIPs) available. The most common have a core of expanded polystyrene (EPS) insulation sandwiched between OSB sheathing. They are built and cut to size in a factory, including openings for windows and doors, and are shipped to the job site ready for installation. Factory production and the use of engineered and recycled wood products offers the potential for a more precise product, less waste, a speedy job site build, and lower embodied carbon.
As the name implies, SIPs can be structural, and used for both walls and roofs, or they can be combined with timber frame, or post-and-beam construction, where appropriately sized posts, beams, and trusses carry the structural loads. This allows for fewer studs in the panels, which reduces thermal bridging and increases the overall R-value of the system. Panel joints are glued and taped and installed to create an airtight building assembly. As with all tight buildings, homes constructed using SIPs cannot rely on passive ventilation and must have well-designed active ventilation systems.
The use of SIPs results in faster construction on-site but requires careful planning involving all trades. The placement of windows, HVAC systems, plumbing and wiring must be designed ahead of time as changes later will be costly and complicated.
Using a SIP as a rim joist (also known as a band joist), as shown in this detail, is one way to provide continuous insulation and air-sealing in an area of the home that is often overlooked. In a traditionally framed floor, the rim joist is set in line with the outside edge of the mudsill. The exterior sheathing is in direct contact with the rim joist and wall above. This creates a cold rim joist, with the potential for condensation to occur, and thermal bridging at…
Structural Insulated Panels (SIP) can create a strong, well-insulated, airtight, building envelope. They can, however, be unforgiving when it comes to moisture management. Most SIP dry slowly if or when they get wet, so back-vented claddings, robust flashing details, meticulous sealing of penetrations, and effective spot/whole house ventilation are all essential.
Band panels are set on the outside edge of the sill around the whole perimeter of the building. Overlap band panels on the sills as called for in plans and with joints opposite that of the sill layout.
NOTE: The GBA SIP details consist of 90 pdfs. Currently, the details are not available as dwg files. These 90 details are copyrighted by Green Mountain Panel and included in the GBA Construction Detail Library with express permission from Green Mountain Panel. All of the SIP Details were drawn by Steve Baczek and reviewed by Peter Yost for Green Mountain Panel, the same team that developed all of the other GBA details.
To see the SIP details with the step-by-step installation procedures, download the Green Mountain Panel Installation Manual.