Residential Light Gauge Steel Framing
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Summary
Residential steel
framing utilizes cold-formed steel members for walls, floors, and roofs. The
framing members are C-sections with standard dimensions similar to wood framing
members in stick-framed construction. Manufacturers promote steel framing as a
cost effective, superior alternative to wood framing.
Details
Steel mills produce
sheet steel, the base material for steel framing. Sheet steel is roll-formed
into the shapes used for framing and is protected from corrosion with zinc
galvanization. Although there are a variety of shapes available, the primary
shapes used in residential construction are the C-shape stud and the U-shaped
track.(*see Figure). Framing members are produced in thickness' from 18 mils (a
mil is 1/1000 of an inch) to 97 mils.
Steel framing members
are produced to strict standards of strength, consistency, and dimensional
stability. Steel framing provides excellent design flexibility due to the
inherent strength of steel, which allows it to span increased distances and it
can be designed to withstand high wind and seismic loads and is
non-combustible.
Installation
Stick-built or
conventional steel framing is typically a one-for-one replacement of wood
framing members for both non-load-bearing and load-bearing applications. The
steel studs, joists and rafters fit into a top and bottom track. Steel framing
members can be cut with a chop saw, aviation snips or electric shears (*see
Figures). The primary fastener used in steel framing is the self-drilling screw
which can be labor intensive when compared to the pneumatic framing nailers
used in wood framing. However, there are new fastening systems that utilize
crimping, welding, and pneumatic nailers that promise to speed up the
construction process. Typically, the top track is not capable of transferring
vertical loads. Studs, joists and rafters must be aligned vertically to
transfer vertical loads . This framing technique is called in-line framing
(*see Figure).
Benefits/Costs
Steel framing contains
up to 28%-recycled material and construction waste generated during framing is
100% recyclable. It is resistant to corrosion, warping, and termites. Framing
members can be ordered cut-to-length which can result in reduced on site labor
costs and reduced on site waste. Framing weighs up to two-thirds less than
conventional materials. Lightweight steel framing lends itself to panelization
techniques that can speed the on site construction process by allowing the
assembly of walls in controlled environments. Figure ** shows panelized steel
framed walls loaded on a trailer ready for transportation to the job site.
Steel framing members also have pre-punched holes that allow for easy
installation of electrical wiring and plumbing.
Limitations
Steel framing members
conduct heat/cold which results in a process called thermal bridging that can
lower the effectiveness of cavity insulation and cause streaking (ghosting) on
the interior finish of walls and ceilings. Exterior insulating sheathing should
be installed in cold climates to mitigate thermal bridging and ghosting
problems. Even though conventional steel framing is very similar to wood
framing, there is a significant learning curve that must be completed before
any cost savings associated with the use of steel can be realized. In-line
framing requires careful layout of studs, joists and rafters to ensure that
they align vertically. There is also a shortage of framing crews trained in the
installation of steel.
Code/Regulatory
Steel framing is
recognized by all major building codes. Recently, a set of prescriptive methods
for residential steel framing was adopted by Council of American Building
Officials (CABO), and are now included in the CABO One and Two Family
Dwelling Code. The prescriptive methods contain tables for stud sizing and
spacing, joist and rafter spans, fastener schedules and construction details.
In areas that recognize CABO, the prescriptive methods will allow the
construction of stick framed steel homes without the certification of a
professional engineer. In areas that do not yet recognize CABO, a professional
engineer must certify the plans.
Availability
There are many
manufacturers throughout the country. These manufacturers typically have a
network of distributors who sell the members directly to builders. Also the
number of building suppliers that stock steel framing is increasing. Even with
the increasing availability, it is typically not as readily available as wood
framing material.
Contact(s)
If you have any
specific questions about this technology and/or its applications please contact
the following resources.
American Iron and
Steel Institute
1101 17th Street,
Northwest
Suite 1300
Washington, DC, 20036
Light Gauge Steel
Engineers Association
2017 Galbraith Drive
Nashville, TN, 37215
615/386-7139
NAHB Research Center,
Inc.
400 Prince George's
Blvd.
Upper Marlboro, MD
20774
HomeBase Hotline
800/898-2842
Fact Sheet Source
The material provided
in this section is used with permission by the National Association of Home
Builders Research Center and the Partnership for Advancing Technology in
Housing (PATH).
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