Study Shows How to Combine SIPs Roofs and Concrete Walls

A new study prepared by the NAHB Research Center and released by the Department of Housing and Urban Development (HUD) shows builders how to improve the durability and energy efficiency of their homes by combining structural insulated panel (SIPs) roof systems and concrete wall systems in one- and two-family dwellings.

Funding for the study — “The Prescriptive Method for Connecting Structural Insulated Panel Roofs to Concrete Wall Systems” — was provided by HUD’s Partnership for Advancing Technology in Housing program, which aims to break down barriers to innovative housing technologies. Support was also provided by the Structural Insulated Panel Association (SIPA) and the Portland Cement Association (PCA).

“Through the specifications provided by this research, builders will be able to reduce costs while more easily building high-quality energy-efficient homes,” said Donn Thompson, AIA, PCA’s residential technology manager. “This truly collaborative effort brought together all the different concrete building system manufacturers with the SIP manufacturers to ensure all the practical solutions of the new technologies are addressed.”

In most cases, the new prescriptive guidelines will reduce the need for additional engineering during the design phase of projects using the two systems, often translating to lower costs for both builders and owners.

“When a licensed engineer is required to determine the appropriate connection system and approve the building plans, the cost is often passed on to the home owner,” said Bill Wachtler, executive director of SIPA. “This important document gives builders and design professionals the right connection systems that have been tested and engineered for most residential applications.”

Structural insulated panels consist of a core of rigid foam insulation sandwiched between two facings, typically made of oriented strand board (OSB). SIPs are available as large as 8’ x 24’ and are extremely energy-efficient, making them ideal for roofing applications.

The study covers all types of concrete wall systems, including insulating concrete forms (ICF), concrete masonry, removable form systems, precast wall panels and autoclaved aerated concrete products.

ICFs and other concrete wall systems provide a high level of thermal resistance for an energy-efficient building envelope. The concrete wall systems also form solid, continuous and airtight walls that prevent heated or cooled air from leaking out, the main cause of home energy loss.

Homes built in high wind or seismic zones were not covered in the study.

“To make a completely energy-efficient building envelope, you have to have well insulated walls, a well insulated roof and an airtight connection between them,” said Wachtler. “As energy costs continue to rise and become a greater concern for home buyers, the winning combination of these two energy-efficient technologies has a strong future in the residential market.”