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Steel vs. Wood Cost Comparison Beaufort Demonstration Homes CHAPTERS:
NOTE: Adobe Reader is required to download, view, and/or print PDF files. If your computer does not have this software, you must first download Adobe Reader, and follow the installation instructions before accessing PDF files from PATH's Web site. January 2002, 94 pages 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 only recently attracted attention for use in load bearing wall, floor, and roof framing applications in residential construction. Despite the availability of cold-formed steel framing, there are still basic barriers that impede its adoption in the residential market. Probably the primary barrier is that the building industry is generally reluctant to adopt alternative building methods and materials unless they exhibit clear cost or quality advantages. A second barrier is how the thermal conductivity of steel affects energy use in homes. Given improvements in the technology over the past few years, it is not clear how steel compares with wood framing in terms of overall cost to the builder. The scope of this project was limited to constructing two identical side-by-side homes at three different locations in the U.S. Each location had unique labor rates, material costs, size, shape and style of construction. The sites include Indiana, South Carolina, and North Dakota. Each site has a house framed with conventional dimensional lumber and a second one framed with cold-formed steel. Blower door tests are to be conducted for all demonstration homes to determine the levels of air infiltration for each house. Co-heat tests are also to be conducted at two sites (Valparaiso, Indiana and Fargo, North Dakota) to determine the energy consumption of each tested house. A modified version of the Group-Timing Technique (GTT) was used to gather information for these houses. The GTT is a work measurement procedure for multiple activities that allows one observer using a stopwatch to make a detailed time study of an entire work crew at the same time. Continuous observations were made on a 15- minute interval and were recorded as tallies on a form that listed the elements of the job. Non-productive time was also identified and removed from the totals to establish a normal time for each component of work. Time values were used to calculate the productivity of each of the houses for comparison. This report is limited to the findings of the demonstration homes in Beaufort, South Carolina. Installed costs of the steel framing material were determined and compared with that of conventional wood framing. Results indicate that the cost of the demonstration steel-framed home is 14.2% more than an identical wood home, however, the framers' labor hours for the steel-framed home were only 4.3% higher than those of an identical wood home. The results also indicated that certain aspects of cold-formed steel (such as interior non-load bearing walls) are within the range that might be expected to be cost-effective with wood. An infiltration test was conducted for each home. Results indicated that both steel and wood-framed homes have approximately the same leakage (infiltration) rate. When using the information in this report, extreme care should be taken in drawing comparisons with costs in a particular area, as local labor rates, availability of materials, and regional skill levels all influence a particular material's final cost. The unit costs developed in this report were based on the data obtained from a small sample. This information does not include non-productive time, builder overhead or profit. Results do not reflect a definitive study but rather indicate whether builders should consider cold-formed steel framing when searching for solutions to lumber problems and concerns. The reader should also be careful when using the cost data shown in Appendix B for a specific activity, as the data provided may not be representative of the true cost for that specific activity in another project, location, or circumstances. Content updated on 12/10/2003 |
