The company I work for in southern Wisconsin specializes in commercial construction. Many of our jobs see us partitioning the interiors of office buildings, manufacturing facilities, and other professional spaces. Fire codes require the use of noncombustible materials in commercial spaces, so light-gauge steel framing is the way to go. While steel currently represents only a tiny percentage of residential framing, the rising price of lumber may yet change that equation. In this article, I’ll limit the discussion to nonbearing interior partitions; structural steel framing typically requires engineering and is a separate focus.
A Case for Steel
Most residential carpenters have little experience with steel framing and may be leery of adopting an unfamiliar material. However, if you’re thinking about testing the waters, the good news is that little is required in the way of specialty tools — you probably already own most of them. The framing techniques are somewhat different, but with a little training, production rates can be comparable to wood framing.
Steel studs are rot- and termite-proof and are galvanized to resist corrosion. They’re also about 60 percent lighter than their wood counterparts, which reduces installer fatigue. The studs are uniformly straight and dimensionally consistent, making plumbing and lining walls a snap. Walls framed with steel are flat and true and they stay that way. And since the studs don’t shrink, twist, or hold moisture, drywall screw pops are unlikely. The studs come with prefabricated knockouts, which simplifies horizontal wiring and plumbing runs. Finally, steel is an endlessly recyclable material; steel studs typically contain at least 25 percent recycled steel.
Studs and Track
Metal studs are available in sizes to match wood framing and in a range of gauges for various applications. The basic nonstructural C-channel stud is made from 25-gauge steel and is suitable for nonbearing partition work. For a stiffer wall or one taller than 10 feet, a heavier 20-gauge stud can be substituted. (You can find wall height tables for nonbearing walls at the Steel Stud Manufacturers Association Web site, ssma.com, and more extensive information in Section R603 of the IRC).
Getting the hang of framing with light-gauge steel studs just takes a little experience. Steel and lumber have different structural properties, but stud sizes and layout are the same.
Deep-leg U-channel can compensate for out-of-level conditions — allowing all studs to be cut to a common length — or contain square-cut studs on raking walls.
Studs are specified by size and minimum thickness. The web and flange dimensions are expressed in hundredths of an inch, followed by a “STUF” letter describing the component section (“S” for stud, “T” for track, “U” for U-channel, “F” for furring) and then the metal thickness, expressed in thousandths of an inch. Thus, a 3 5/8-inch 25-gauge stud with a 1 1/4-inch flange may be designated “362S125-18.”
Note that gauge numbers don’t match thickness numbers, as in this example, where 18 is used to designate a 25-gauge stud. Furthermore, the thickness within a gauge designation is allowed to vary within a certain range, and thicknesses can vary considerably from one manufacturer to the next. Specifiers typically refer to thickness, not gauge, when selecting steel framing materials.
Standard U-channel — which we call “track” on the job — has 1 1/4-inch flanges and serves in place of the top and bottom plates used in wood framing. Studs fit inside the track, which is nailed or screwed directly to the floor and the ceiling. Deep-leg track gives a little more coverage for special applications.
Ordering steel. Calculating quantities is really no different from doing a wood framing takeoff. There are distinct wall types, some extending to the roof deck, some to the bottom of the bar joists, and others only to the existing suspended ceiling grid. Specifications should provide the appropriate size, gauge, and stud spacing — typically 16 inches on-center — for any given job. Most supply houses stock 8-, 9-, 10-, 12- and 16-footers, with special-order lengths taking only a few extra days to obtain. If you need custom lengths, or if you need 100 studs of a particular length, you can order them precut, saving time and labor on site. I once ordered precut 26-foot-tall 20-gauge studs to partition a factory interior; we were dividing a painting area from open office space.
In commercial framing, nonbearing partitions may extend to the underside of the roof deck.
The bottom of the bar joists, each of which calls for a different fastening method.
Tools for Steel Framing
When it comes to cutting studs heavier than 25-gauge, a dedicated metal-cutting chop saw is a must. A decent 14-inch model will set you back only about $200. (It’s not safe to use a wood-cutting miter saw to cut steel, because of its high rpm.) There are two types of blades used to cut steel: abrasive blades and the newer carbide-tooth blades specifically made for cutting ferrous metal. Abrasive blades throw more sparks than toothed blades do, but at $9 apiece versus $130 for a carbide blade, we use them exclusively. With a 14-inch chop saw, you can cut a full bundle of studs to length before cutting the banding — a considerable time saver. When an abrasive blade is worn to the point where it can no longer cut completely through a bundle, we toss it.
A 14-inch metal-cutting chop saw is handy for gang-cutting bundled studs and mandatory for cutting heavier 20-gauge steel members.
Gloves. We always wear them. Cut channel edges can be razor sharp. Lightweight cloth gloves with a rubberized coating on the palms are best.
Inexpensive rubberized cloth gloves keep hands from getting sliced on razor-sharp cut edges. Here, a short slit in the end of one track prepares it for mating with another length.
Snips. A good pair of straight-cutting sheet-metal snips sees routine use on our jobs, trimming studs and cutting flanges to make tab-style header and blocking connections (more on this later). The going gets rough in steel heavier than 20-gauge; in fact, 20-gauge steel will wear out a pair of snips pretty quickly. I like the yellow-handled pro-series Wiss snips (618/654-2184, cooperhandtools.com).
Also, while you don’t really need them, it’s still nice to have right- and left-cutting pairs handy in your toolbox for the rare occasion.
Clamps. Vise-type locking C-clamps, commonly used in metal fabrication, are indispensable in steel framing. They’re used to temporarily hold a stud or section of track in place during leveling and can prevent materials from shifting while you install a screw. Irwin locking C-clamps (800/464-7946, irwin.com) are smooth-acting and reliable and are sold in various throat depths, including a long-throat model that sometimes comes in very handy.
A fundamental tool collection covers most steel framing tasks.
Screw gun. One tool most steel-framing experts recommend is a 2,500-rpm clutch-drive VSR screw gun. It’s used both to connect framing members and to fasten the drywall. Using drywall guns — which run at 4,000 rpm and higher — is generally not advisable, since they spin too fast and will strip a screw before it fully penetrates the steel.
If you don’t like dragging a cord around, cordless screw guns run at a suitably low rpm and can do the job. For 25- to 20-gauge framing, any 14-volt or higher tool is adequate, but an impact driver provides a slight advantage in helping the screw to penetrate the steel.
Laser. For laying out, plumbing, and straightening walls, a self-leveling rotating laser is essential. The self-leveling feature ensures that if the laser is jostled, the line will recover its accuracy rather than provide a false reference.