A structural insulated panel (SIP) is a product that fuses a foam core, like expanded polystyrene, between two outer skins of Oriented Strand Board (OSB) to create a super-strong construction panel. They are used to construct exterior walls, roofs, ceilings and floors. Homes and buildings constructed from SIPs offer superior insulation qualities, exceptional strength, fast installation and a host of benefits to the environment.
Superior Insulation -- The foam core of a SIP provides higher insulation values than many other insulation materials used in traditional stud-wall construction. Because SIPs have fewer gaps -- and because studs do not interrupt the insulation -- SIPs homes have proven to be less drafty.
"Nearly 20 percent of a traditional stud-wall is made up of studs and other non-insulated materials," said Bill McGarrity, vice president at Pacemaker Plastics in Newcomerstown, OH. "The R-value of fiberglass insulation in the lab is significantly higher than how it performs in an actual wall. But SIPs, because they are comprised of solid insulation, perform virtually as well in an actual home as they do in a lab test. They also act as a barrier to external noises better than homes made from traditional construction methods."
Owners of homes using structural insulated panels may qualify for the EPA's Energy Star Home designation, given to homes that benefit the environment through reduced energy usage. Homes that are given this designation may qualify for lower-interest mortgages or other benefits.
Exceptional Strength - Since the finished panels are an integrated building product, literally acting as a structural component they are able to withstand and even surpass typical loads caused by winds, snow and seismic activity. There have been many documented instances of houses constructed with SIPs having fared severe weather conditions with minimal damage.
Fast Construction and Finishing -- SIPs are joined together quickly and easily by inset splines. An experienced three-person crew can complete the panel erection of a standard 2,000 sq. ft. house in as little as one day and completely "dry-in" the SIPs in as little as three days. Because windows, door openings and roof gables can be precut within the SIPs at the point of manufacture, precision measuring and cutting at the job site are significantly reduced. SIPs also make inside finish work easier to complete. Drywall goes up fast by affixing it to the interior OSB panel. Cabinets also are installed quickly since they can be bolted directly into the OSB panel and electrical distribution is easily accomplished by running electrical wire through horizontal and vertical chases that run inside of each panel.
Environmental Benefits -- According to the Structural Insulated Panel Association (SIPA), SIPs offer several benefits to the environment. Because SIPs effectively replace conventional stud-wall construction, fewer mature forest products need to be harvested. The outer OSB skins of SIPs are made from "engineered wood" that is manufactured from renewable, fast-growing trees. And because SIPs offer superior insulation qualities, heating and electric bills are reduced and the result is that fewer fossil fuels need to be burned.
SIPs are available in a variety of shapes and sizes and can be used to construct a variety of different residential and commercial buildings. SIP applications include the following:
Timber- and Metal-Frame Buildings -- There has been a rebirth in the popularity of timber- and metal-frame buildings due in large part to SIPs. These panels allow timber- and metal-frame buildings to be constructed quickly and affordably.
Cathedral Ceilings -- SIPs are ideal for cathedral ceilings in log cabin or timber-frame roof applications. The panels are simply affixed to the exterior of the roof trusses, providing superior insulation. Shingles are then applied.
Custom Applications -- SIPs can be made in many thicknesses and of a variety of skin materials to meet different load span and insulation requirements. In many cases, window and door openings, gable end walls and plumb-cuts can be made in the factory according to specifications. This ensures ease of installation at the job site.
SIPs were first introduced in the 1950's, but recent developments in the industry have resulted in significant market growth.
"SIP manufacturers are seeing growth of between 15 and 30 percent a year," said Butch Johnson, panel marketing director of Perma R Products of Johnson City, TN. "More and more home buyers are embracing this high-quality approach to home building."
When choosing between a home using SIPs versus a traditional construction method, quality is the chief reason structural insulation panels are chosen. In current market conditions, the costs of SIPs and traditionally constructed homes are comparable.
"Generally people building a SIP home are not as concerned about initial cost as they are about quality," said McGarrity. "They want the added strength, quiet and insulation values that a SIP home offers. But the fact is, because of the efficiencies and ease of building a SIP home, the overall cost of building one is very competitive with more traditional construction."