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Structural Insulated Panels (SIPs) - Fiber-Cement-Faced

Structural insulated panels with a finished surface

A cross-section of a fiber cement faced structural insulated panel shows an inner and outer skin and a core of super-insulating expanded polystyrene (EPS) glued together with a special high-strength glue and dried under extreme pressure.

Structural Insulated Panels (SIPs) are prefabricated insulated structural elements for use in building walls, ceilings, floors and roofs. They are made in a factory and shipped to job sites to replace conventional stud or "stick frame" construction. SIPs may be called foam-core panels, stress-skin panels, sandwich panels, or structural foam panels.

SIPs are engineered laminated panels with solid foam cores and structural sheathing on each side. The most common types of sheathing or skins materials are oriented strand board (OSB) and plywood. Some manufacturers produce panels with fiber-cement sheathing.

Skin Material
Cementitious SIPs are typically manufactured of cellulose reinforced cement boards, for inside and outside skins. The material can be taped and finished on the interior surface. The fire-resistive cement board eliminates the need for gypsum drywall. The exterior surface can be painted or coated with a vinyl or synthetic stucco permanent finish. If siding or brick veneer is to be used, oriented strand board (OSB) can be applied on the exterior to accept nailing of siding or brick wall ties. It is not necessary to have both OSB and fiber-cement board on one side for brick and stucco applications. OSB can be used instead of fiber-cement board for such an application. However, there may be some difficulty in finding a manufacturer that produces this type of SIPs.

Applications
Cementitious SIPs can be used for below and above grade applications. They can be used to construct foundation or basement walls, floors spanning up to 16 feet between supports, load-bearing walls up to four stories and roof panels up to 20 foot spans.

Details and Connections
Cementitious SIPs are fastened together with power-driven screws through the inner and outer skins into either cement board or wood splines. Because of the strength of the panels, no headers are needed over standard size doors and windows. Connection details are similar to those of OSB-sheathed panels.

Erection
Cementitious SIPs are light weight, and panels can be erected by as few as two workers, with minimal equipment.

Thermal Efficiency
Cementitious SIPs are as energy efficient as OSB SIPs. Consumers often think that R-value is of primary importance, but effective air sealing is also significant. For the best energy performance, a continuous air barrier and uniform insulation coverage, with as few gaps as possible, are needed. Every air leak and every thermal bridge adds to heating and cooling bills. Cementitious SIP panels are air-tight and fully insulated.

Durability
Buildings constructed with cementitious SIPs typically will last longer and require less maintenance than other types of SIPs panels. Fiber-Cement Board used as skins will not rot, burn, or corrode. It has a higher fire rating than OSB faced SIPs, and in most residential applications no drywall would be necessary. Cementitious boards will not support black mold growth, and they have a high resistance to moisture absorption. They are rot and vermin resistant, and are not significantly affected by water vapor.

Finishes
Fiber-cement panels can have different finished looks, such as a wood grain, stucco, or smooth. With the smooth finish, stucco, vinyl siding, brick or stone can be installed.


Energy Efficiency

Cementitious SIPs are as energy efficient as OSB SIPs. Consumers often think that R-value is of primary importance, but effective air sealing is also significant. For the best energy performance, a continuous air barrier and uniform insulation coverage, with as few gaps as possible, are needed. Every air leak and every thermal bridge adds to heating and cooling bills. Cementitious SIP panels are air-tight and fully insulated.

Quality and Durability

Buildings constructed with cementitious SIPs typically will last longer and require less maintenance than other types of SIPs panels. Fiber-Cement Board used as skins will not rot, burn, or corrode. It has a higher fire rating than OSB faced SIPs, and in most residential applications no drywall would be necessary. Cementitious boards will not support black mold growth, and they have a high resistance to moisture absorption. They are rot and vermin resistant, and are not significantly affected by water vapor.


Easy


Fiber-cement board would be somewhat higher in cost than OSB. All SIPs would be higher in cost for customized, complex layouts.


Not Applicable


Most cementitious SIPs systems are recognized by major code organizations. However, currently there is no specific prescriptive language in building codes addressing SIPS. Manufacturers of cementitious SIPs provide technical design and support services to ensure adherence to codes. Manufacturers also have evaluation reports from the International Code Council (ICC) that list structural characteristics of their panels. Evaluation reports can be obtained directly from the manufacturer or from the ICC.


Not Applicable


The installation of electrical wiring and plumbing lines may require special tools and techniques. Because SIPs structures are more airtight, special attention should be paid to the design of mechanical ventilation to avoid potential backdrafts. Extra care should also be taken to see that gas appliances are properly vented.


Not Applicable


Fiber-cement board would be somewhat higher in cost than OSB. All SIPs would be higher in cost for customized, complex layouts.

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the NAHB Research Center. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.