This report is the second of three in a multi–year study comparing thermal performance of steel and wood-framed houses conducted for the U.S. Department of Housing and Urban Development (HUD), the Steel Framing Alliance, and the National Association of Home Builders (NAHB). This study is conducted by the NAHB Research Center, Inc.

Light gauge steel framing has been used for many years for interior non-load bearing and curtain walls in commercial construction. However, cold-formed steel members have been gaining wider acceptance in load bearing wall, floor, and roof framing applications in residential construction. Steel stud framing for residential building is gaining popularity due to simplicity of construction
and similarity to wood frame assembly. Despite the availability of cold-formed steel framing, there are still basic barriers that impede its adoption in the residential market. This report addresses the question of how the higher thermal conductivity of steel affects energy use in homes.

When building with steel framing members, it is highly recommended to compensate for the thermal bridging inherent in steel. If a structurally equivalent steel stud were to replace wood without consideration of thermal performance, the overall clear wall R-value of a wall can be reduced by 25 percent1 in a typical wall section. Using exterior rigid foam insulation can
compensate for this reduction.

The approach taken in the Beaufort demonstration site was to build a wood house to local standard practices. A nearly identical steel house was also designed using the prescriptive method2. Additional exterior wall insulation was not required for the steel framed house according to the Thermal Design Guide3. The long-term (1-year) monitoring was designed to determine how these two houses perform thermally in a humid southern climate. Monitoring
various temperatures and heating and cooling energy use during the test period in unoccupied houses are the basis of the evaluation.