SIP Homes, Structural Insulated Panels, SIP Panels

FAQs

Q: 01. What are SIPs?
Q: 02. How much faster can I build with SIPs?
Q: 03. How much labor can I save with SIPs?
Q: 04. How much money can I save with SIPs?
Q: 05. How green are SIPs?
Q: 06. How strong are SIPs?
Q: 08. How do I properly size HVAC equipment?
Q: 09. How important is ventilation?
Q: 10. How do SIPs improve indoor air quality?
Q: 11. How do SIPs react to Fire?
Q: 12. Are SIPs compatible with other building systems?
Q: 13. What considerations do you need to take into account when building with SIPs vs. conventional framing?
Q: 14. Can SIPs be modified on site?
Q: 15. How are electrical wiring and fixtures installed?
Q: 16. Are SIPs susceptible to insects?
Q: 17. Can SIPs be replaced or repaired if damaged?
Q: 18. What about roofing? Does a building with a SIP roof need to be ventilated?

What are SIPs?

A: Structural insulated panels (SIPs) are high performance building panels used in floors, walls, and roofs for residential and light commercial buildings. The panels are typically made by sandwiching a core of rigid foam plastic insulation between two structural skins of oriented strand board (OSB). Other skin material can be used for specific purposes. SIPs are manufactured under factory controlled conditions and can be custom designed for each home. The result is a building system that is extremely strong, energy efficient and cost effective. Building with SIPs will save you time, money and labor.

How much faster can I build with SIPs?

A: SIP homes go up faster than traditionally framed buildings. A properly trained SIP installation crew can save a significant amount of time in a build cycle[1]. Panels can be manufactured as big as 8- by 24-ft., so entire walls can be put up quickly, reducing dry-in time. SIPs can be supplied as ready to install building components when they arrive at the jobsite, eliminating the time needed to perform individual jobsite operations of framing, insulating and sheathing stick-framed walls. Window openings may be precut in the panels, and depending on the size, a separate header may not need to be installed. Electrical chases are typically provided in the core of panels, so there is no need to drill through studs for wiring.

_{[1] Edminster, Ann and Yassa, Sami. Efficient Wood
Use in Residential Construction: A Practical Guild to Saving Wood,
Money, and Forests. Natural Resource Defense Council, 1998.}

How much labor can I save with SIPs?

A: Because SIPs are prefabricated, the amount of additional framing required is minimal. SIPs are always straight and true, there are far fewer callbacks, no culling studs, or need to straighten walls. SIPs also provide a uniform nailing surface for both interior and exterior finishing.

How much money can I save with SIPs?

A: Builders can save money through decreased construction and labor costs. The superior whole wall R-values and building tightness capable with SIPs allow HVAC equipment to be downsized and ductwork to be minimized. Builders can also significantly reduce jobsite waste disposal and temporary heat during construction. Homeowners that incorporate other energy efficient features with SIP construction can benefit from the energy efficiency of a SIP home with reductions in heating and cooling costs of 50 percent or more possible and may, qualify for Energy Efficient Mortgages, and enjoy higher appraised value.

How green are SIPs?

A: Energy efficiency
Structural insulated panels are one of the most environmentally responsible building systems available. A SIP building envelope provides high levels of insulation and is extremely airtight, meaning the amount of energy used to heat and cool a home can be cut by up to 50 percent. The energy that powers homes and commercial buildings is responsible for a large portion of greenhouse gasses emitted into the atmosphere. By reducing the amount of energy used in buildings, architects, builders, and homeowners can contribute to a clean environment for the future.

Resource use
The insulation used in SIPs is a lightweight rigid foam plastic composed of 98% air, and requires only a small amount of petroleum to produce. The foam insulation used in panel cores is made using a non-CFC blowing agent that does not threaten the earth’s ozone layer.

Waste minimization
Since SIPs are prefabricated in the factory, there is less jobsite waste that needs to be landfilled. Factory fabrication is often done using optimization software and many manufacturers recycle factory scrap to make other foam products.

How strong are SIPs?

A: The structural characteristics of SIPs are similar to that of a steel I-Beam. The OSB skins act as the flange of the I-beam, while the rigid foam core provides the web. This design gives SIPs an advantage at handling in plane compressive loads.

SIPs can be engineered for most applications. Detailed information on the structural performance of SIPs is available from SIPA member manufacturers.

How do I properly size HVAC equipment?

A: The high insulating properties of SIPs allow smaller HVAC equipment to be used. When working with an HVAC contractor, make sure their calculations take into account an accurate estimation of typically low levels of air infiltration in a SIP home. Proper HVAC sizing is crucial because an oversized HVAC system will fail to reach the steady operating rate the equipment was designed for. Short cycling HVAC equipment will be less energy efficient and require more maintenance than properly sized HVAC equipment.

How important is ventilation?

A: SIP buildings are extremely airtight and require mechanical ventilation. Ventilation systems bring fresh air into the building in controlled amounts and exhaust moisture laden and stale air to the outside. By limiting air exchange to controlled ventilation systems, SIP homes allow for all incoming air to be filtered for allergens and dehumidified, amounting to better indoor air quality. Proper ventilation is important in all homes to preserve indoor air quality.

How do SIPs improve indoor air quality?

A: The tightness of the SIP building envelope prevents air from gaining access to the interior of the home except in controlled amounts. A controlled indoor environment is both healthy and comfortable. Humidity can be controlled more easily in a SIP home resulting in a home that is more comfortable for occupants and less prone to mold growth and dust mites.

How do SIPs react to fire?

A: Residential building code requires that foam insulation be separated from the interior of the building by a material that remains in place for at least 15 minutes of fire exposure. . Structural insulated panels faced with 0.5” gypsum drywall meet this requirement.

Commercial builders may need a one hour fire-rated wall or roof, which is achieved by testing and listing a specific wall or roof assembly to ASTM E119 with an accredited certification agency. Individual SIPA member manufacturers should be contacted to confirm listed assemblies they can provide.

Are SIPs compatible with other building systems?

A: SIPs are compatible with other building systems. Wall panels can sit on a variety of foundation materials, including poured concrete, blocks, or insulated concrete forms. SIPs are sized to accept dimensional lumber and are seamlessly compatible with stick framing. Builders may choose to build with SIP walls and a conventional truss roof, or stick walls and a SIP roof with little difficulty. SIPs are also popular as a method of providing a well-insulated building envelope for timber frame structures.

What considerations do you need to take into account when buidling with SIPs vs. conventional framing?

A: The majority of construction with SIPs is very similar to conventional framing. SIPs accept dimensional lumber and are fastened together using staples, nails or screws. Proper sealing is especially crucial in a SIP structure. All joints need to be sealed with specially designed SIP sealing mastic or low expanding foam sealant, and/or SIP tape. Voids between panels and unused electrical chases need to be filled with low expanding foam. In addition to sealing, planning and consideration needs to be applied to material handling. Although smaller 8- by 4-ft. panels can be set by hand, larger 8- by 24-ft. panels require the use of equipment to unload and set.

Can SIPs be modified on site?

A: On-site modification can easily be done using a few additional SIP specific tools. Panels can be cut using a beam saw or a beam cutting attachment to a circular saw. The foam core can then be recessed for splines or dimensional lumber using a hot wire foam scoop or specialized angle grinder attachment to recess the core.

How are electrical wiring and fixtures installed?

A: Electrical wires are pulled through precut channels inside the core of the panels called “chases.” Manufacturers cut chases during the manufacturing process according to the electrical design of the home. Electricians can then use fish tape to feed wires through panel chases without compressing the insulation or having to drill through studs. Wiring can also be run through baseboard raceways and in the cavity behind the beveled spacer on SIP roof-to-wall connections.

Are SIPs susceptible to insects?

A: Although termites do not feed on the foam panel cores, there have been instances in which panel cores have been hollowed out by these insects and used as a nesting ground. Many manufacturers offer SIPs with borate treated foam to provide termite resistance. Termites may also be deterred through the use of a specifically designed steel mesh. Both these treatments are highly effective, but they are not a substitute for careful termite prevention and maintenance, as with any other wood structure.

Can SIPs be replaced or repaired if damaged?

A: If panels are damaged, a structural engineer needs to assess the damage to determine what is cosmetic and what is structural. If the damage is only cosmetic then the source of moisture must be determined and fixed, whether it is from inside or outside. If the damage is structural, then the source of the problem must be identified and a structural solution to the problem must be found. That can be done by either a site modification of the panels or replacement of the panels, depending on the extent of the damage. In the event that panels are damaged, the manufacturer and installer of the panels should be notified. There are SIPA members who can act as a consultant to assess the damage and recommend repair or replacement strategies.

What about roofing? Does a building with a SIP roof need to be ventilated?

A: The area inside a SIP building envelope is considered conditioned space and will be ventilated by the building’s HVAC system. There is no need to provide a vented attic beneath a SIP roof, and doing so would compromise the conditioned space of the building. Most roofing manufacturers specify how to attach their product to SIPs. Please contact the roofing manufacturer for application instructions.