The use of steel framing for residential applications often hits a stumbling block when it comes to labor-intensive installation such as load bearing headers.
The use of light gauge steel framing for home construction has increased recently due to advantages such as rot and termite resistance, uniformity, and cost when compared with wood. However, widespread adoption of steel framing in homes has been hampered because it can reduce labor productivity-especially with assemblies that require a greater amount of fastening, such as load-bearing headers. Steel L-headers that consist of single or double steel "L" angles have been introduced to simplify header installation and to save time by significantly reducing the amount of cutting and fastening.
Traditional steel headers typically consist of double "C" channel, light gauge steel members, either back-to-back or in a box-beam configuration. The labor productivity of light gauge steel framing is poorer than wood frame construction due to the difficulty of fastening steel members. Traditional steel header assemblies require a disproportionate amount of fastening.
The L-header is a new header design that cuts labor time over the C-channel design. Steel L-headers consistsof two "L" shaped, light gauge steel angles. The shorter leg of the angle is about 1-1/2 inches wide, and the longer leg ranges from 6 to 10 inches long. The short leg rests on the wall's top track and the longer leg extends down toward the window or door opening. Steel thickness typically ranges from 16 to 20 gauge. Headers can either be single (one side of the wall only) or double (both sides of the wall). They have demonstrated structural adequacy for residential buildings in areas of low to moderate wind speeds. L-headers are also suitable for use in wood-frame buildings.
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The use of steel L-headers results in more energy efficient walls than walls with the traditional back-to-back or box beam steel headers. The L-header long legs are not fastened together, thus reducing the thermal bridge in the framed wall. L-headers are easy to insulate due to the presence of air space between the angle legs.
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Steel L-headers are manufactured to strict ASTM tolerances. They are manufactured using steels that conform to industry, national, and international standards. The durability of steel is very well documented in many publications and journals. The American Iron and Steel Institute’s (AISI) publication RG-9605 titled “Durability of Cold-Formed Steel Framing Members” summarizes the performance of steel-framed members in common residential applications.
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Steel L-headers are easy to install. They do not require skilled labor. L-headers are fastened to the top track of steel-or wood framed walls. Screw guns and self-drilling screws are typically used to fasten L-headers. Span tables and construction details are readily available.
Initial cost of steel L-headers are reported to be as much as 30% less than costs for traditional back-to-back and box-beam steel headers. Steel L-headers use about 30% less screws and 30% less material. Labor savings are even greater for L-headers; they do not need to be pre-cut to length and do not need additional stiffeners or connector. Unskilled laborers can easily install L-headers.
Not Applicable
Span tables and construction details for L-headers are readily available from the Steel Framing Alliance (SFA). The Header Design Standard (published by AISI) includes design methodology for single and double L-headers. The 2006 edition of the International Residential Code will contain span tables and construction details for steel L-headers. Currently, users of steel L-headers present their jurisdiction with a copy of the L-Header Guide (AISI and SFA) for their approval.
Not Applicable
First, the load-bearing steel wall is framed using non-load-bearing wall details, that include window and door openings. The light gauge steel L-angle is then attached with self-drilling screws above the opening on one or both sides, depending on the opening width. Care should be given to use the correct size fasteners and place them where specified. The same tools and materials are used as with conventional light gauge steel framing.
Not Applicable
The primary benefit of steel L-headers is that they reduce the amount of labor and material required for building steel framed walls. L-angle material costs about the same as traditional "C" channel steel framing of the same depth.
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