Enercept Explains: Building Science Behind Structural Insulated Panels

With so many pieces to be assembled, it's easy to understand why stud frame houses take considerable time and labor to build. Enter Structural Insulated Panels (SIPs) – the prefabricated building components used to produce a structurally superior, better insulated, faster to erect, and more environmentally friendly house than its stick framed counterpart with fiberglass insulation.

Enercept SIPs are solid sheets of building material constructed of a foam core sandwiched on each side by a layer of oriented strand board (OSB). They are used for walls and roofs but can also serve as floors and foundations. Enercept panels are fabricated at our plant in Watertown, South Dakota, and shipped to the construction site, where they can be assembled quickly to form a tight, efficient building envelope.

Enercept wall, roof panels, and below grade panels are manufactured with a foam insulating core, usually 5 1/2 inches to 12 1/2 inches thick, providing the ultimate protection against heat and cold. Panels are prefabricated to custom sizes and dimensions and are shipped to the job site ready for installation based on a predetermined sequence.

Openings for building details like windows, doors, electrical chases are all pre-cut in the factory. The panels are installed one piece at a time and fastened together using nails. All joints are then sealed with SIP tape, creating an extremely airtight envelope. Enercept SIPs fit together like puzzle pieces, making their construction simple and straightforward,  resulting in a structure that is built faster, is more energy efficient, eco-friendly, and costs less to own.

The main goal while building a SIP house is to make it as airtight as possible, which helps the insulation work to its maximum capacity. Enercept’s Insulated Connecting Posts are unique and join the walls together. This inventive SIP system results in a solid envelope of insulation where even the connection posts have a foam core. Therefore, Enercept SIPs have the ability to provide continuous insulation to virtually eliminate thermal bridging. As the panels are set into place, they are joined to not only afford greater energy efficiency, the hand-beveled edges of the lumber in the post makes for easy installation. The panels easily slide into the next adjoining panel smoothly in a tongue-and-groove fashion.

Enercept’s wall panels feature another innovative feature called fly-by-corners. In short, the OSB on the exterior of each corner panel extends beyond the ESP insulation. This allows installers to trim the OSB (and the foam, if needed) to fit precisely even if the foundation or floor deck has imperfections.

The other tricky elements to keep in mind are wind and water -- or ventilation and moisture to be more precise. Because the goal is to seal SIP homes into tight envelopes (not like drafty stick frame homes with constant gaps between insulation), a ventilation system that can exchange heat between outgoing air and fresh air is recommended. SIPs are extremely energy-efficient and don't need the heavy-duty HVACs of other buildings.
Smaller units can run on less power for longer lengths of time and dehumidify in the process. 

The science behind SIP is very simple, and there are a number of benefits to building this way:

Materials: EPS is cost effective, available, durable, easy to produce, and easy to work with. The oft-used OSB outer skins come from replenishable, quick-growing softwood trees, and­ SIP components are recyclable.

Efficiency: Buildings built with SIPs have greater thermal efficiencies and fewer insulation breaks for heat to escape. They offer more uniform temperatures while decreasing the heating and cooling load. Plus, because they require smaller HVAC systems, they also decrease the amount of greenhouse gasses.

Advantages: SIP homes are quieter than stick-frame houses -- and they tend to be healthier. As long as proper ventilation and filtration are maintained, the house maintains better indoor air quality, leaving dust, mold, and allergens at the door. Want to hang something heavy up on the wall? There's no need to locate studs – the whole wall can handle the load.

Strength: Instead of having the weight of the structure centered on the studs, the entire shell is able to shoulder the load. Enercept homes also tend to do better during natural disasters like hurricanes and earthquakes – although this is in no way a guarantee that the house will weather the storm.

Industry: SIPs are becoming more popular in the building industry. For the building contractor, building with SIPs can help deal with labor shortage issues and extend the building season. If the insulating shell can be put up in a few days, crews can spend the rest of the winter working on the interior.

Bottom Line: SIP homes generally cost marginally more to build compared to stick-frame homes. Besides the money saved during construction (remember the prefab savings, the decreased labor cost, the lack of materials waste, and the smaller HVAC), they also offer long-term savings. Besides reductions on utility bills, SIP homeowners may be eligible for tax breaks and energy-efficient mortgages. SIP homes also tend to have a higher resale value as well.