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Structural Insulated Panels as a Roof at Far Reach Home

Case Study by Nathaniel Kinne
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Structural Insulated Panels as a Roof at Far Reach Home
Building Envelope
Structurally Insulated Panels as a Roof
Thurston County
Rowland Zoller, Thurston County
Matt Cooper and Eileen Ryan
Scott Homes, Inc.
Scott Homes, Inc.
5 Star Built Green EERE's Builder's Challenge (HERS 39 rating) Energy Star Certified EPA Indoor airPLUS Qualified Home Silver EVHA Award


This home’s exterior envelope was constructed entirely from Structural Insulated Panels (SIPs), and the interior was heated with a Ductless Heat Pump and included a Heat Recovery Ventilator for indoor air quality, all resulting in an extremely airtight, energy efficient non-standard home. While no building codes were ignored, the home incorporates several systems many building officials may be unfamiliar with.

Permitting Process

There is no code section detailing the use of SIPs as a roof structure, however an engineer or architect may sign off on this usage. Premier SIPs, the company that supplied the Panels, offers technical information for SIPs in roofing and other non-prescriptive uses. Plans were only approved after several educational meetings with Thurston County Building Officials, including Rowland Zoeller, Scott Bergford, his designer, and several building scientists.

Project Description

Matt Cooper and Eileen Ryan wanted to build the most cost effective energy efficient home they could, so they turned to Scott Bergford of Scott Homes, Inc. Scott Homes has built with Structural Insulated Panels for 18 years and is very familiar with their level of performance. However, the company had never used the panels in the entire envelope. Scott struck a deal with the Matt and Eileen where, if he could experiment by building their house entirely with SIPs, including floor, walls, and roof, he would absorb the extra cost of the thicker SIPs. Washington State University Extension Energy Program was brought in to study the project and record the performance of the house.

Before a design could be settled on or even permitted, Scott Bergford spent time educating the permitting department he’d have to work with. He met with engineers and building scientists to educate himself and the plans examiners on how a house like this could be built, be structurally sound, and meet all relevant code requirements.

The home’s envelope is comprised entirely of SIPs, making the whole house conditioned space, including the attic spaces. When a blower door test was administered, the results showed .65 ACH50, or .65 Air Changes/Hour at 50 Pascals, a result just above the industry’s most airtight method of construction, the Passiv Haus(r). To meet Passiv Haus standards, a structure must show .6 or less ACH50, meaning the Far Reach House is not far off.

The residents are very pleased with the finished home, as it is extremely airtight and very cozy. According to the residents the daily operating cost averages $3.20/day. Energy use is lessened by simple activities like cooking or having guests over, both of which naturally heat the home.

The house has been rated 5 Star Built Green, it meets EERE’s Builders Challenge (HERS 39)rating, is Energy Star certified, is an EPA Indoor airPLUS Qualified Home, and will be receiving either the Silver or Gold EVHA award in Feb 2012.

After construction it was shown that the 12 inch panels used for the roof were in fact too thick and therefore were not as cost effective as a slight thinner panel would be. The extra cost is not accounted for by the extra thickness.


Approval Requirements

Had to meet all structural code requirements and SIPs supplier's guide lines.

Project Contacts
Owner: Eileen Ryan Builder: Scott Bergford Scott Homes (360) 357-9167 Owner: Peter Bergford Scott Homes (360) 357-9167
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