Insulating Concrete Forms for Residential Construction - 5/9/2005 - Home Foundation Structure Framing

Insulating Concrete Forms for Residential Construction - Demonstration Homes

This is a summary of a report prepared by the NAHB Research Center for the U.S. Department of Housing and Urban Development, and the Portland Cement Association. The full report is available for purchase.

Executive Summary

With sponsorship provided by the US Department of Housing and Urban Development (HUD) and the Portland Cement Association (PCA), the NAHB Research Center coordinated four demonstration projects to evaluate the use of Insulating Concrete Forms (ICF) in residential construction. The demonstration homes are located in Virginia Beach, Virginia; Austin, Texas; Sioux City, Iowa and Chestertown, Maryland. This report presents observations and experiences from these sites.

The Research Center staff and the demonstration home builders and/or general contractors were in communication throughout the home construction process. Research Center staff visited each site several times. Initial observations documented the construction details of the homes and recorded the construction via photographs. Site visits were made after construction to perform thermal testing and interview homeowners and builders concerning their satisfaction with the homes. Thermal testing consisted of collecting air infiltration data and thermographic imaging, which displays heat transfer through wall frame members in a color video format. Homeowners were interviewed concerning their impressions of the design, construction, thermal comfort, sound comfort, and overall satisfaction with their homes. Builders, or general contractors where appropriate, were interviewed concerning the construction process and construction costs. Insights about concrete handling (mix, pour); form placement and bracing; code requirements and other construction details were discussed. Costs of construction are compared to typical framing in the specific geographical location.

These homes show the advantages for homeowners and the implications for builders of residential use of ICF construction. The homeowners are pleased with their houses. Advantages of ICFs cited by homeowners include reduced transmission of “street noise” to the indoors and an appreciation for new technology. Builders did not have difficulty in selling these homes, and plan to continue using this construction.

Although installed costs of the ICF walls were higher (1-5% of final sales price) than the builders typical practice, they found the cost premiums to be worth the benefit of this construction method. Several observations and suggestions are presented to reduce this cost premium for future ICF projects.

Testing showed the solid concrete wall (clear wall) has less cold spots than frame construction. However, construction details of the openings, architectural penetrations and foundations influence greatly the level of energy efficiency. Winter infiltration rates for the demonstration homes, calculated using data from fan depressurization (i.e. blower door), ranged from 0.15 to 0.55 air changes per hour.