General contractor Stephen Stoddard has been building homes for so long he can gauge the span for a floor joist or estimate the maximum load for a structural 2x4. But he doesn’t do either anymore.
“My insurance company doesn’t want me to certify anything,” says Stoddard, a principal at Lighthouse Construction in Winthrop, Mass. So he submits specs to a structural engineer or to his lumber dealer to produce a computerized layout that proves the plan is structurally sound. These days, many builders employ those computerized drawings because of stricter building codes and to optimize their lumber packages.
Both engineers and lumber dealers typically rely on an engineering design software program—often from an engineered wood supplier—to analyze loads as the first step of the takeoff process. Some dealers send the plans to a software-equipped truss plant to make the call instead.
“When builders were dealing with 2x10s, they knew to double them up on the stairway; they knew what size header they needed,” notes Mike McCraw, national engineering manager for Georgia Pacific. “As houses got bigger, spans got longer, and engineered lumber came to be. That gut feeling for how to build houses went away and builders needed help.”
Software from engineered wood suppliers—typically not offered directly to home builders—can analyze loads in half the time it would take a builder to do the calculations without a computer. So most pros rely on either a computer-equipped engineer or lumber supplier to determine detailed placement and sizes for load-bearing wood members.
California and several Northeastern states require an engineer’s analysis, while building codes in most Southern and Midwestern states do not dictate that an engineer has to be involved, says Ross Theilen, customer software and technology director for Weyerhaeuser. He adds that the software is not designed to replace the engineer during the structural analysis. “This is a tool to automate those calculations,” he says.
Builders approach the structural analysis of their plans in different ways. Bethesda, Md.–based production builder Winchester Homes produces architectural drawings, and then uses an engineering firm for the analysis. The builder’s lumber dealer prices the materials and uses software to create a 3D model of the framing and then to precision-cut, label, and mark the lumber so it’s ready for installation. Others leave the design and analysis to their lumber suppliers.
Leverage Dealers’ Expertise Engineered wood manufacturers advise builders to leverage the expertise of their lumber dealers. Besides ensuring structurally sound beams, dealers who do the analysis and put together packages can control costs better than builders who shop individual stick prices.
Dealers also can offer advice about the spacing of joists to avoid plumbing penetrations, and are far more likely than builders to own the automated saws that make precision cuts and label members.
Theilen also suggests that builders encourage their suppliers to leverage the builder’s work. If the builder uses a building information modeling program to draw detailed, 3D plans, it might be worth it to work with a dealer whose software can import those plans so no redrawing is necessary.
“Not a lot of dealers can do that,” says Theilen. “They redraw. But the software is catching up. That’s going to get easier with time.”
Rachel Barron contributed to this report.
