The Structural Insulated Panel Story
Reprinted with permission of the Structural Insulated Panel Association.
SIPs are an engineered wood building material that has been considered to be as revolutionary as the personal computer. SIPs are the fastest growing engineered wood product because they save labor for the contractor while providing a more comfortable and durable structure. They have been shown to be much more energy efficient than old-fashioned stick framed builds.
There is no simpler, more efficient way to build, period. Architects love them for ease of design. Builders love them because of lower labor costs, less waste and speed of construction. Consumers love them because of strength, durability, level of comfort and energy savings. Environmentalists love them because it requires fewer trees.
The illustration at right shows the components of a Structural Insulated Panel. The three elements of a SIP act together, to outperform conventional building materials in strength and seismic capacities. The original discovery of this came during the mid 1930's when the US Forest Products Research Laboratory constructed some test homes in the Los Angeles area.
The rigid foam core that is present in all SIP products is significantly more energy efficient than all other forms of insulation because air is unable to move through it. The result is a more comfortable and quieter indoor environment. The panels also offer a flat, solid surface for attaching finish materials like drywall, siding and cabinets. Because SIPs don't contain many studs, (common 2 by 4's), SIP construction produces no twisting or warping of lumber.
An added benefit is that SIPs use up to 65% less raw timber than other construction techniques. This, in itself, is a huge benefit for our environment. The wood used in SIPs is typically either farmed wood or weed wood. This means that rapidly maturing second growth, not old growth, trees are harvested for the sheathing or "skins" of SIPs. Further, the entire tree is used, not just the inner core. SIPs are widely recognized as the most environmentally friendly product utilized for house framing that is currently available.
SIPs are put together with many different combinations of joining mechanisms, usually called splines. These splines can be plain old lumber, engineered lumber products like I-Joists, strips of OSB called surface splines or even cam locks, (that work like little deadbolt locks pinning one panel to the next). SIPs use the various properties of the different splines to actually alter the panels' stiffness. That "engineering" allows the panels to be used at different spans or under different loads, (like the weight of snow or the speed of wind). Panels have been used successfully in every conceivable climate and load condition in the world.
With a single I-Joist between them, one panel edge is butted to the next panel edge. Nails or staples then connect each panel to the I-Joist. This combination is found most often in floor and roof applications.
SIPs are fully compatible with any floor or foundation system. Once the floor is finished, the walls are ready to be tipped into place. The walls can utilize either a boom truck, crane or good old-fashioned muscle to put them into place. The thing carpenters like about panels is that there are really no special tools to buy or new skills to learn. Framing is just done with larger pre-cut pieces.
Once the walls have the top plate installed, its time to set beams so the roof has something to sit on. Then using a boom truck, the roof system is "flown" into place. The result of using roof SIPs is a true vaulted ceiling, sometimes called a cathedral ceiling. Because SIPs use rigid insulation, this is very cost-effective space that can be used as either a second story or a loft. These SIP designs are also the most energy efficient way to construct a home.
When the house is "dried in", meaning closed in from the weather, other people begin the process of finishing the panels with wiring and plumbing. Wiring is a simple task for the electrician because virtually all SIP makers pre-form wire raceways called chases into the panels. They are put in at the predetermined height for both switches and outlets. This creates a network of conduits or access runs for the electrician. The process may involve a small amount of extra wire, but is about the same as any other electrical wiring job in residential construction. The plumber usually doesn't put any water lines in the exterior wall, but through the floors and into the interior of a cabinet base, (look under your kitchen sink). But plumbing vents go through the SIP walls with just a small amount of preparation by your manufacturer or builder or by using a loop or island vent. Consult with your builder or panel manufacturer to see what your local building codes require.
After these trades have completed, you may finish your panels as mentioned above with drywall or plaster inside and siding, brick, stucco, stone or any other appropriate exterior material on the outside.
The real savings are now pocketed with every passing day. SIP homes have been routinely reported as requiring half the energy to heat and cool home.
SIPA Manufacturing members are required to maintain Independent, third party Quality Assurance Programs in their plants or factories.
©1999 Structural Insulated Panel Association