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.

Larry and ValerieVanZomeren live in Coopersville, Michigan. Their home was constructed in 1995 using structural insulated panels. Just recently, a violent storm with winds ranging from 80 to 130 miles per hour caused widespread damage to numerous buildings and homes in Coopersville. More than 400,000 people were left without electricity. During the storm, 5 trees, all in excess of 80-feet tall with trunk diameters from 12 to 16-inches, fell directly on the VanZomeren's home. At two and a half tons per trunk, the structure of the house remained intact and unharmed except for a few shingles and some siding.

In March of this year, a deadly tornado ripped through the town of Clermont, Georgia. Elton Palmer's home, built with SIPs, was among the few left standing. Five other homes were completely destroyed less than a quarter mile away.

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 effectivey 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.

SIP Applications

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.

Marketplace Advancements

SIPs were first introduced in the 1950's, but recent developments in the industry have resulted in significant market growth.

According to the Structural Insulated Panel Association (SIPA), there are more than 100 U.S. panel manufacturers who produce in excess of 32 million-ft2 of panels every year. If current industry projections hold true, SIP production could grow to between 50 and 112 million-ft2 by 2000.

"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. "Perma R Products is seeing growth between 25 to 40 percent. More and more home buyers are embracing this high-quality approach to home building."

When choosing between a home using SIP 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."

The mission of Habitat for Humanity International is to eliminate poverty housing and homelessness around the world. Thanks to structural insulated panel (SIP) technology, Habitat is achieving its goal faster.

Building Blitz

During the week of November 8th, 1999 a team of volunteers arrived at a construction site in Lothian, MD to participate in a Habitat for Humanity "building blitz." The goal was to construct a home from start to finish in less than one week. Bob Vila, host of television's Home Again, was there to provide live updates each morning for CBS's Early Show.

The "building blitz" actually began months before the actual construction with a contest sponsored by Residential Architectural magazine for the design of this Habitat for Humanity home. Architects were asked to propose a high-quality, high R-value home that could be constructed quickly and affordably. To maximize field installation speed and quality, the winning design incorporated pre-engineered, factory built components, including SIPs. In fact, the entire house, walls and roof, was framed utilizing structural insulating panels.

The structural insulated wall panels arrived in Lothian with the window and door openings, and electrical chases already cut out. This precutting and the fast and easy connections of SIPs, allowed the home to be framed within four hours and completely enclosed by early afternoon.

Supporting Habitat's Mission

One challenge in operating a volunteer-driven organization is soliciting and managing the volunteer activity. Because of limited volunteer time - the Arundel Habitat typically works on homes only on Wednesdays and Saturdays - Habitat members see SIPs as being especially valuable to their cause.

"Working only two days a week, it takes about four months for us to build a traditional wood frame house," said Linda Gray, executive director of the Arundel Habitat for Humanity affiliate, which oversaw construction of the Lothian home. "But because SIP homes require fewer labor hours, it allows us to get the families under their new roof faster and provide more convenient scheduling for our volunteers. We see SIP homes as being very volunteer friendly."

R.B. Belch, the Arundel Habitat's construction manager, said another key benefit of SIP homes is the savings in utility costs. Though the total installed cost of SIP homes is slightly higher than wood frame methods, they do provide cost savings due to energy efficiency over the long run.

"The SIP home we built in Lothian provides much higher R-Value than the traditional wood frame homes built in the past and that will result in significant savings over the course of the year for the family living there," he said.

Habitat's headquarters in Georgia provides general guidelines for constructing homes, but each local affiliate is responsible for choosing the construction methods used. Belch said that though there are many pluses in using SIPs technology, the Arundel Habitat is hesitant to switch completely from wood frame methods. Of five homes being built in 2000, all will be constructed using traditional stud wall methods.

"In order for us to use SIPs, we need to have a crew leader who is experienced with the installation process," said Belch. "Though the construction is very straight forward, there is a learning curve involved and it is still easier for us to build homes using familiar methods."

The Future