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How Structural Insulated Panels Work

Raise the Roof: Building with SIPs
SIPs are fitted together like a jigsaw puzzle.
SIPs are fitted together like a jigsaw puzzle.
Bart Coenders/iStockphoto

­Unlike stud frame houses, which are usually constructed completely on-site, houses using SIPs tend to be mostly prefabricated. As we read about on the last page, structural insulated panels are made by manufacturers and shipped out to construction sites, where each wall goes up whole. This means that even though a new homeowner is likely to be shelling out some extra cash on materials, he or she ­will probably be saving money on labor costs and jobsite waste. One thing homeowners shouldn't skimp on is experience. While SIP houses aren't as perplexing to figure out as a Rubik's cube, they can present a challenge for someone attempting to build one for the first time -- maybe more along the lines of one of those monochromatic jigsaw puzzles. Having someone with a little know-how can make everything go much smoother.

The main goal while building an SIP house is to make it as airtight as possible, which helps the insulation work to its maximum capacity. As the panels are lifted into place -- often with the use of a crane or a forklift -- they're joined together carefully. This is typically accomplished with a variety of items like expanding foam, sealing tape, sealing mastic and good, old-fashioned nails. The important thing to remember is that if the house is going to come out right, the manufacturer's directions must be followed to the letter. Yet even despite that, it may be necessary to complete some small on-site modifications to the prefab sections (another reason having a pro can be an asset), but with the right tools, a quick fix can be done in a snap.

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) they need to be built with care. For example, you'll need to select a ventilation system (typically one that can exchange heat between stale outgoing air and fresh new air) which is a suitable size for the building's needs. SIPs are more energy-efficient, so they don't need the heavy-duty HVACs of other buildings. Smaller units can run on less power for longer lengths of time -- and they dehumidify in the process, which is key to keeping mold worries off your mind. Another way this comes into play is between the siding, roof shingles and outer shell of the SIPs. Here too, ventilation and moisture can be a problem unless the panels are given adequate space to breathe and drain.

But once the house is finished and the moving van pulls to a stop at the curb, it's time for the kudos to start rolling in. On the next page, we'll examine what kind of return an owner can get from an SIP home and how the panels can be beneficial for people looking to take the plunge into prefab.