PATH - A Public Private Partnership for Advancing Housing Technology

PATH Case Study

SIPs Below Ground


Continued from Page 2

SIPs have better insulation than conventionally framed walls, providing increased air tightness and thermal performance. As a result, SIPs have higher R-values, which rate the resistance to
heat transfer.

R-Values for Walsh's Cabin:

Basement walls.............32

Basement floor..............16

Above-grade walls.........16



"We are extremely pleased with the quality of the product, the build process and the finished product. The SIPs panels allowed us to go from gravel to a building closed to the weather in less than 10 working days--including a below-grade structure and two floors of construction. Amazing since we did not have the usual benefit of a crane on site! We avoided concrete and traditional construction waste, both of which are costly to dispose of on any site and especially so on an island. I would use SIPs again on any project."

-- Gerald Walsh,

Panels weigh approximately four pounds per square foot, so 4-foot panels are light enough to be set by hand. Exterior walls for most houses can be erected in less than a day. Nails, panel sealant and expandable foam are used to fasten the panels to top and bottom plates. Vertical connections typically use plywood splines with nails being replaced by screws.

[IMAGE: SIPs installation process] "The installation went smoothly, but we did have to do everything by hand," Stendel says. "Also, we had to do it in stages because there wasn't a second floor in part of the house. We had to do the main floor walls, but leave the back wall off, so we could get our panels for the upper wall where we could handle them."

"Projects just go much faster when using SIPs. And when you can get in and out faster, your customer is happier because you have provided them with good service in a shorter construction time."


With SIPs, the ease and speed of assembly makes it possible for houses to be placed under roof within days rather than weeks. While basic carpentry skills are required, assemblers need not have the skill levels of conventional framing crews, which further reduces builder costs.

[IMAGE: Installing the upper wall panels]

Technology Highlights

This project included the following PATH-profiled technologies:

"While SIPs cost a little more at the outset, the price difference isn't much," Stendel says. "Some builders will look at initial cost and the four- to six-week wait to receive the panels, and just walk away. When you look at the overall savings--from dumpster and disposal costs because there is very little waste; a more quickly enclosed shell that keeps the site dry and mold free; and the reduced sizing of HVAC systems with shorter runs up interior walls rather than extending to exterior walls--there isn't much difference in the cost factor. Those are hidden savings that builders don't always take into account when they start."

"As for callbacks, if we get them, it's usually for something pretty minor, like condensation forming into an area that hadn't been sealed by subs yet. Even then, it's pretty rare."

"When comparing to stick framing, it is apples to oranges. I would challenge the stick framers to build a house that is comparable in strength, insulation, and tightness, and be environmentally responsible for the same cost. I don't think they would even be able to come close."

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Content updated on 9/1/2006

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