This report presents the results of thermal studies that were performed at the NAHB Research Center and testing that was conducted at the Oak Ridge National Laboratory on prototype slit web studs. Thermal test results showed that the prototype slit web studs performed 17 percent better than the solid-web studs.

As an extension of this project in 2003, the NAHB Research Center was retained to develop maps to show where the 3.5” and 5.5” thermal studs would meet model energy code requirements with various thickness exterior insulation sheathing and to define residential market size described by each zone of the maps. The 2003 ICC International Energy Conservation Code was used to identify the energy and insulation levels (i.e., effective wall Rvalue)
for each zone, assuming R13 cavity insulation in 3.5” walls, R19 cavity insulation in 5.5” walls and 15 percent glazing with a U-factor of 0.45. The NAHB Research Center Builders’ Practice Survey and a Steel Framing Alliance market analysis was used to define the market potential for each zone of the thermal zone map. The maps for a 3.5” solid-web stud, 5.5” solidweb stud, 3.5” slit-web stud and 5.5” slit web stud are shown on the following pages. From this data, the table below provides the percentage of U.S. housing starts that would comply with the model energy code using each of the methods.