As the general manager of a custom home builder in Orlando, Fla., Mike Williams is very familiar with concrete and steel as building materials. His usual routine, as it is for most Gulf Coast builders, is to construct a first level of masonry block over a concrete slab foundation and then top that with a structural lumber second floor and sometimes light-gauge steel studs for non-load-bearing interior walls.
But for one custom home last year, Williams got a firsthand look at a pair of related, yet far less common, systems for home building: structural steel framing and precast concrete panels. Though he's unsure if or when he'll employ either again, he sees the advantages they offer the industry. "They both have a definite future in residential," Williams says. "But builders have to be open to new ways of doing things."
For most alternative structural systems looking to eke out market share in the residential realm, getting builders to try something new is the biggest bugaboo to mainstream acceptance. This is a problem for insulated concrete forms (ICFs) and structural insulated panels (SIPs)–both the subject of part one of this series that appeared in the April issue (page 75)–as well as for structural steel framing and precast concrete, which we'll discuss below.
There are other hurdles, too. Building codes that lag behind technology and cutting-edge builders, a lack of skilled labor for these new systems to serve demand, price premiums for materials and labor, and logistical and supply chain issues that take contractors out of their comfort zone of their local lumberyards are all factors that stand in the way of widespread market acceptance.
For those and other reasons, wood still rules the jobsite. Conventional lumber framing boasts nearly 80% market share of the structural material for all new, single-family detached houses. Alternatives are making some headway, having increased their combined market penetration into single-family construction by more than 12 percentage points in 10 years to 20.3% at the expense of conventional stick framing. But that share gain is primarily limited to the innovators and early adopters, those builders and contractors eager to integrate new technologies and systems to deliver specific benefits, such as enhanced energy efficiency. It's the mass middle of the industry that needs persuading now. Both steel framing and precast concrete advocates think they have the right pitch to sway a critical mass of home builders. Neither material is a stranger to construction, having achieved success in the commercial sector. In residential, however, their combined market share is an estimated 3.5%, according to the NAHB Research Center, or about 53,000 new single-family detached houses in 2006.
"Single-family detached housing is the toughest nut to crack, but there is a tipping point for an increasing number of builders to try precast," says Brian Bock, vice president of sales and marketing for Dukane Precast in Naperville, Ill., specifically regarding energy-efficiency, life-safety, and/or sustainability issues that might push individual builders to try the system.
For LBM dealers, structural steel's supply chain is much more accessible than that of precast concrete, except that steel's use has fluctuated downward with recent commodity prices while precast's popularity is growing steadily among home builders. Regardless, until either system creates a critical mass of demand, dealers would do well to simply keep tabs on their progress and perhaps look for opportunities to support, if not stock, them.
Structural Steel Framing
Though the finished frame appears to be similar to conventional stick-built, steel components deliver more uniform dimensions and performance to maintain structural integrity, albeit with a different set of tools and framing practices.
Credit: Photos: Left: www.constructionprogress.com; right: Courtesy Steel Framing Alliance
The primary difference between non-load-bearing steel channels and studs used for interior wall framing and those used for structural steel components and assemblies is the gauge (or thickness) of the material. Load-bearing sections are typically 16- to 20-gauge, while so-called drywall studs and related components are 24- or 26-gauge. Steel framing components are galvanized and considered "light-gauge," and are cold-formed as opposed to hot-rolled steel I-beams and other heavy-gauge components.
During the past 20-plus years, steel framing's market share in single-family residential reached as high as 1.2% in 2000, per NAHB's calculations. As of last year, however, it stood a half percentage point below that, thanks in large part to lower composite lumber prices and spiking global steel costs. That's a far cry from its estimated 38% share of the commercial construction market, according to the Steel Framing Alliance (SFA) in Washington.
But steel proponents and manufacturers see greater potential for the product in housing, pointing to specific geographic markets, such as Hawaii and the desert Southwest, and multifamily construction, where acceptance and use is significantly higher among home builders. "Steel framing is a relatively new entrant in the residential segment, but one in which there is an opportunity to generate three times the demand [compared to commercial]," says SFA president Larry Williams, referring to the greater number of homes of all types versus non-residential buildings constructed each year.
Steel's advantages over wood include a higher strength-to-weight ratio that enables longer spans at smaller dimensions, the net effect of which is more-open floor plans and greater resistance to high wind and seismic loads. Steel also is inorganic and of consistent quality end-to-end, meaning it won't warp, twist, rot, or otherwise react to climate changes in application, as dimensional lumber is wont to do. Steel is non-combustible, adding to its life-safety benefits. It's also resistant to termites and other wood-boring pests.
Pre-insulated to achieve even greater thermal benefits, precast wall panels can be set by crane with only a few trained workers in perhaps a third the time of a conventional wood frame.
Credit: Photo: Courtesy Portland Cement Association
Once you get a steel frame erected, in fact, it looks like a shiny wood frame, with the telltale wall studs, roof trusses, and bracing you'd likely see with lumber. It sheathes and finishes with the same materials, requiring little, if any, changes in those specs. And, unlike other alternatives, steel has a long track record of code acceptance and a contractor-training infrastructure through the SFA and other trade associations and unions, albeit primarily serving commercial framers and drywallers to date. Material prices historically were stable until 2004, when global demand doubled the material's price in a few short months, from which the industry is still recovering.
So why hasn't steel taken off among home builders? Simply, the system requires framers to carry an entirely different set of tools. Hammers become screwguns, while utility knives and chalk lines are replaced in a framer's toolbelt with snips, vise grips, and felt markers. Usually, instead of a wood framer switching to steel (or being skilled enough to do both), builders switch to steel framers–if they can find them.
That fact, in turn, severely limits a builder's ability to use the material as a structural system in all but a few markets. "I've built all-steel houses, and both then and now there's no one doing it [as a specialty trade]," says Orlando custom builder Williams. "From a labor and [materials] sourcing perspective, there are few options in this market."
For the small-scale, second-floor shell he built out of steel last year, Williams had to import a crew from another market and supplement it with a local commercial drywall crew to finish the job.
"The lack of lead framers who know steel framing is our biggest hindrance in single-family," admits SFA's Williams. Price is another, specifically as it relates to the installed cost of a steel frame by inexperienced crews or those in short supply able to leverage premium wages. "Worst case, steel is about 81 cents per square foot more than a wood-framed house," he says.
To combat those issues, the industry is evolving into panelization from the precut or uncut "sticks" that suppliers traditionally provide to a jobsite. An example: recently unveiled insulated steel-framed panels from Accelerated Building Technologies, a joint venture of Dietrich Metal Framing and NOVA Chemicals. "They're like SIPs, specifically in lessening the labor-cost issue [with steel]," says Brian Kutchma, the venture's vice president of sales and marketing.
Kutchma is targeting lumberyards as his primary conduit for the preassembled, lightweight panels once product demand grows beyond the 400-mile shipping radius from a lone manufacturing facility in Cincinnati. "Ideally, we'd like to get lumberyards to finish them [cutting openings, providing connectors] and sell a package of panels and ancillary products," says Kutchma. "We'd prefer dealers look at this as competitive with lumber, not as a specialty product with a high margin."
Sourcing steel framing does not appear to be a hurdle to its acceptance among home builders, as is the case with almost every other alternative system. The metal building materials supply chain includes local lumberyards and, more often, specialty drywall dealers. "We see more steel framing moving through traditional distribution because of increased demand [in certain markets and applications]," says SFA's Williams. That being said, large orders, especially for structural steel, are typically ordered and shipped direct from a fabricator.
As popular as steel interior stud framing has been for light commercial jobs and a smattering of houses in climate- and pest-sensitive markets, lumber dealers have taken to stocking non-load-bearing product and/or sourcing it and heavier gauges as special orders. "Several of our lumberyards do a good business in steel framing," says Joe Koenig, president of Trim-Tex Drywall Products. The company sells a variety of drywall products through a network of more than 2,400 local dealers, a third of which are independent or small-chain lumberyards. "They've been willing to diversify a bit in order to keep the ticket."