First of all, what are SIPs? In this context at least, SIPs are Structural Insulated Panels. As the name implies the panels are prefabricated with insulation and can be used for load bearing walls, floors and roofs. They are constructed of a rigid foam insulation core sandwiched between two layers of wood panels such as OSB. Typical SIPs are 8’ in one direction and up to 24’ in the other direction. The panels come in various thicknesses providing different insulation values, with core thicknesses typically matching standard framing lumber sizes. Cores are provided with preformed chases for electrical runs and panels can have pre-cut openings for doors and windows. SIPs are typically delivered to the homesite on flatbed trucks ready to set in place.
Ok, so now back to the original question: Why SIP’s? For me the bottom line answer is simply value relative to costs. When comparing overall costs to achieve a high performance envelope (exterior walls and roof) as required in our climate, it is hard to beat SIPs. True, the material costs for SIPs is higher than standard framing lumber and insulation. However, labor costs for SIPs construction can be much lower due to the speed and ease with which the envelope can be assembled. When expenditures for additional materials and the labor to install necessary for a framed assembly to match the performance of SIPs construction are included, the overall costs of frame construction become much higher.
Benefits and characteristics of SIPs leading to higher value/lower costs, include the following:
Higher quality, less chance for costly mistakes
Continuous insulation without regularly spaced studs that cause thermal bridging
Not dependent on skill level of on site insulation installers
No need for additional air/vapor barriers that are complicated and expensive to install
Pre-cut openings for windows and doors
Short learning curve for easy installation
Panels are pre-fabricated in factory environment for higher quality control
Fewer subcontractors to schedule and coordinate
Interior surfaces of panels are smooth and flat, ready for finishes without shimming or labor intensive installation
Interior skin is structural allowing direct attachment of railings, trim and cabinetry without additional blocking
SIPs integrate easily with standard frame construction
I’d be interested if anyone has any comments, additional thoughts or questions on this subject or any other, for that matter . . . .
For more information regarding SIPs contact Big Sky R-Control or Premier SIPS