On the four-acre site of the Verona project in Irvine, Calif., Greystone Homes (a Lennar subsidiary) faced a tough engineering challenge: Squeeze in 47 large, detached luxury homes, sized with floor plans between 1,788 square feet and 2,105 square feet. Architect Daniel Gehman with Thomas P. Cox Architects, at the behest of the builder, specified steel framing for all three floors. The result: tall, narrow homes that exceeded the region's tough seismic requirements--and sold out completely in the $700,000 range, well above the initial pro forma price of $500,000.
"Lennar is very much into steel," notes Gehman. "The more we got into using it for framing, the more it made sense for a variety of reasons. But really a big part of it was that because the homes are so close together, we foresaw a lot of problems with staging."
Lightweight steel framing solved that issue, he says, because modular sections could be assembled off site and fastened into place.
Mark Kemmerer, vice president of operations for the South Coast (Calif.) division of Greystone Homes, adds that the move to panelization--steel and otherwise--is on a fast track at Lennar.
"It cuts cycle time and total labor and takes the guesswork out of fluctuating lumber costs," Kemmerer say. "We just had a price spike in lumber out here. Before the spike, lumber was cheaper [than steel]. Now steel is actually cheaper. And we're not hauling a truckload of wood scraps to the landfill at the end of the job."
For the Verona project, homes were built off site in modular components, labeled, and shipped to the site. Before that, however, whole sections could be set up for inspection at a remote, indoor site.
"We actually had a framing walkthrough inside an aircraft hangar," notes Gehman. "They assembled various sections, and we could walk through them."
Working with steel on a residential project of this scale raised several challenges for Greystone. For one, California's tough energy code, Title 24, requires the use of special web-type steel framing pieces similar to the one shown (inset). These studs slow thermal transfer through the wall by as much as 50 percent compared to standard steel studs, based on Canadian studies by the National Research Council.
From permitting to finishing on these homes, the builder faced a continuous learning curve. Local code officials asked a lot of questions. And some of the age-old detailing problems with innovative structural systems surfaced. For example, framing arch-top windows required on-site construction of custom hybrid jambs. In addition, the transition between oriented-strand board and galvanized steel wall sheathing on the exterior caused problems for the stucco applicators.
In both cases, however, the problems led to more innovation. The builder found, for instance, that he could use steel panels for all of the sheathing without significantly impacting cycle time or cost.
Kemmerer says that many manufacturers have identified detailing problems when framing with steel and have begun to respond.
"More and more companies are coming up with new technologies to make this work," notes Kemmerer. "For instance, we have a local guy who now makes all our arched tops in Laguna Beach, [Calif.], so we'll be eliminating that hybrid framing."
While the extensive use of steel framing is the big story here, the subplot is the clever use of shared spaces to achieve higher density. Residents share all outdoor areas between the homes, including driveways and a heavily "greenscaped" central courtyard.
To make the communal concept work, window sightlines had to be arranged cleverly to provide privacy and light.
Gehman says the two major categories of buyers--mature move-down families and young, professional couples--are used to close quarters. And the market for new homes far exceeds supply.
"[Communal space] didn't even show up on their radar," the architect says. "These lots are non-existent, so we thought, rather than give people fake backyards, we would create tiered outdoor areas, with semi-public, semi-private sections."
Says Kemmerer, "Back when we started building with steel three years ago, we had trouble getting contractors. We got some resistance. But now we're into a normal situation, with three or four bids on a job--and no resistance."
Gehman points out that Lennar's move to steel is a business choice by the builder--not demand driven. "For the buyer it's a fun, nifty aspect of the house that they hear about in the buying process," he notes. "I honestly can't tell you that a lot of these clients are sophisticated enough to worry about what the framing is--or even things like mold. It's really the builder who's behind it."
While the architect is willing to go on record saying that a steel-framed, steel clad house creates a solid line of defense against mold and defect litigation, Kemmerer defers. The legal climate is so charged in California right now that Lennar understandably urges its people to take the Fifth with reporters. But the company's actions say what they won't. They like the prognosis for modular steel framing.
"We're starting a senior townhouse community in Fountain Valley next week," Kemmerer explains, "all framed the same way. That's 54 units. Then we'll be starting 95 [steel-framed] townhouses in Harbor City. We're very committed."