SIPS: Structurally Insulated Panel Systems

The largest cost of owning a custom home is almost always the cost to build it but the costs of utilities, maintenance, and the cost of insurance must be considered in order to know the true cost of ownership. In custom building, it’s too often that we get preoccupied with the cost of pretty things – bells and whistles – and sometimes clients overlook the drivers of those long term costs.

Building materials and Finish Selections should be evaluated over the anticipated life span of the project. By evaluating those long-term costs, we are educating ourselves so we can make the correct decisions to keep the house on budget in both the short and long term. A building component, like the fiberglass pilings we recently used for an elevated foundation, cost less in the long run despite a higher initial cost than traditional timber or concrete piles because they’re stronger and allow us to use fewer of them. They’re also longer lasting and easier to work with and they don’t rot, get eaten by termites, or splinter!

Everyone who gets a power bill knows their power usage patterns and efficiency of the various mechanical systems are directly related to the cost of their utilities. We clean our AC filters, add programmable thermostats and use efficient light bulbs in order to limit the size of our power bills. Still, it’s far less obvious how the cost of construction can relate to the overall, long-term cost of owning a new house. Simply put, spending a little more on the front end can save big money over the lifespan of a home and nowhere is the decision more obvious than on construction materials and methods. Specifically, insulation, doors, and windows are where most of the expensive leaks and inefficiencies lie. Insulated windows and doors are required by code. A certain amount of insulation is, as well, but the difference between code compliance and what we call “performance construction” can be drastic. Over the long run, an investment in high efficiency windows, doors, and insulation should result in a decrease in the long term cost of ownership.

In the south, air conditioning costs are the major driver of utility bills and a significant portion of the cost of construction. In order to save on power bills, we should buy efficient air conditioners, but it’s also important to build an efficient structure so that your new super-efficient heat pump isn’t spending half its time cooling or heating air that leaks into and out of your home. To maximize return on the investment from an efficient and expensive air conditioning system, it’s necessary to properly insulate and seal your new or old home.

One of the best ways we’ve found to do this in new construction is by using SIP panels. SIPS or “structurally insulated panel systems” are a high performance building material used for structural framing of walls, floors, and roofs. They’re constructed from a layer of foam sandwiched between two sheets of plywood or OSB sheathing. Generally they are 6-12” thick and are factory made to exact sizes and shapes. Done correctly, the panels are quick to install, extremely strong, produce very little waste, and provide for an incredibly well insulated combination of strength and efficiency. The tight tolerances provided by CAD designed and computer cut wall penetrations make it easier to properly seal window and door openings. When assembled with expanding foam or bituminous gasket construction, the level of air infiltration is quantifiably less than traditional construction. In fact, a recently finished SIP house we built was analyzed for leaks and unwanted air infiltration using blower air testing and proved to be 12 times tighter than required by EPA’s Energy Star standards.

Watch for more about SIP SIP construction and air leak testing in my next article or at the SIPA website: http://www.sips.org/about/what-are-sips/