“Advanced” frequently means “complicated,” but that’s not the case with structural insulated panels (SIPs). The panels provide a way to build homes, apartments and commercial buildings faster, with higher energy efficiency and with less waste than other construction methods.
Manufacturers produce SIPs by laminating wood “skins” (typically oriented strand board) with a structural-grade adhesive to a rigid insulating foam core (usually expanded polystyrene). The components work together as an engineered system, providing high-strength walls, roofs and floors.
Building professionals can use SIPs to help reduce heating and cooling energy consumption up to 60 percent, reduce framing scrap by two-thirds, and shave weeks off construction schedules. For all these benefits, the process of designing and building with SIPs is straightforward.
Following is an overview of the benefits of SIP construction and tips for making the switch. Energy Efficiency
SIP buildings are substantially more energy-efficient than comparable construction methods. The large panels have fewer gaps to seal than stick framing, and have continuous, high-performance insulation across their height, width and depth. As such, they reduce air leaks and thermal bridging to help lower energy use. The U.S. Department of Energy (DOE
) conducted tests that found SIP construction to be 15 times more airtight than stick framing with fiberglass batt insulation. Many contractors are using SIPs as part of net-zero energy buildings that are so efficient they can meet all of their power needs from onsite resources. Rapid Installation
Contractors can order SIPs in custom-cut sizes for rapid installation at the jobsite. The panels are available in sizes up to 8-by-24 feet that can be used to build entire wall and roof sections, as well as the complete building envelope, more rapidly than cutting and assembling individual wood or steel framing members. Additionally, SIPs eliminate the need for separate framing and insulation work. SIP manufacturers also will pre-cut electrical chases in the panels, which enables faster wiring than cutting holes through numerous studs. SIPs are also available with pre-cut window and door openings, which eliminates labor for installing headers and framing the openings.
The Structural Insulated Panel Association
reports that properly trained crews can reduce framing time by 55 percent compared to conventional wood framing. Faster construction can help save labor costs and interest on construction loans, as well as enable earlier occupancy and revenue generation.
For example, Community Development Programs Center of Nevada installed 100,000 square feet of SIP walls in just 80 days for a four-story, 82-unit affordable housing complex in Las Vegas. Across town, contractors for the Jacob E. Manch Elementary School used SIPs to reduce the framing schedule for the 70,000-square foot project from the 121 days allocated by the school district to only 47 days (a 60 percent time savings). In the process, they saved more than $2 million in total construction costs.
In addition, contractors can save on finish labor because SIP walls are consistently straight and plumb. Further, SIPs virtually eliminate framing materials waste and can lower disposal fees. Working with SIPs
Architects can design SIP buildings from the ground up, or existing building plans can readily be adapted for SIP construction. A SIP manufacturer will review the plans and produce shop drawings that detail how many panels, and of what sizes, will be needed. The manufacturer then fabricates the panels and labels each one with a unique code that corresponds to its location within the building.
SIPs are compatible with nearly any type of building system, including poured concrete or block foundations. Manufacturers size SIPs to fit with standard lumber dimensions so they can be easily integrated with interior walls constructed of stick framing, or with floor systems using wood I-joists. Contractors can use SIPs for roofs, or add conventional roof trusses on top of SIP walls.
SIPs are fastened together with nails, screws or staples using standard power tools. Because they are pre-sized, cutting is typically not necessary, but the panels can be field trimmed if necessary.
A primary difference between SIP construction and stick-built framing is the need to manage staging of the panels on the jobsite to avoid moving materials multiple times. Smaller panels can be set by hand, but large panels require equipment to unload and place.
In most applications, SIPs are structurally self-sufficient. Where point loads from a beam or header require additional support, contractors can install additional splines at in-plane panel connections. SIPs also can be used as curtain walls over steel or timber frames, which is common for large interior spaces such as gymnasiums.
As with any high efficiency building envelope assembly, SIP structures typically require mechanical ventilation to ensure sufficient fresh air volumes for occupant comfort and to help control interior moisture levels. Nevertheless, SIPs’ high-performing insulation allows for smaller-size HVAC equipment than is required in typical construction, which saves both capital and operating costs. The necessary size and type of mechanical ventilation system varies by climate, building occupancy and other factors. It is important to consult a qualified mechanical engineer to ensure an appropriate design. Choosing a SIP Manufacturer
Some SIP manufacturers will work with contractors, architects, engineers, and specifiers to provide design support. Manufacturers also differ in their ability to provide a range of code acceptance reports, which can be crucial to ensure smooth project completion.
Ask prospective manufacturers what services they provide in the shop and in the field, their production lead times, and how they can help ensure code compliance. The Structural Insulated Panel Association provides links to manufacturers’ websites, along with a host of useful information on working with SIPs.