Case Study Examines Pluses and Minuses of OVE Framing
A new publication from the NAHB Research Center — ”Advanced Framing: Its Practical Use in Residential Construction” — tells why optimum value engineered (OVE) framing has never really caught on despite its ability to cut costs and reduce energy consumption.
The publication presents an unvarnished case study by the NAHB Research Center — the original developer of OVE practices — of one particular job site in which OVE practices were applied for the first time.
An alternative to standard technical how-to guides, the study prioritizes OVE techniques based on how easily they can be implemented and their impact on material and energy savings. It was funded by the Department of Housing and Urban Development and the Department of Energy.
For the case study, the Research Center’s Building America team tallied wood use and estimated material savings for a home built by vocational high school students in Lancaster, Pa. Student framers applied advanced framing techniques including 24-inch on center in-line framing, single top plates, header hangers, right-sized headers, ladder blocking at partition walls, and two-stud corners.
Not all of the techniques were fully implemented and some were subsequently modified. For example, 1-inch nailers were added to two-stud corners to provide a nailing surface for siding and to aid the screeding process for cellulose wall insulation.
All told, advanced framing resulted in material savings of 14.2% for wall framing (20.4% savings compared to standard 2x6 framing) and 8.4% for floor framing over conventional framing practices.
Construction supervisor Mike Dodson said he learned a lot about advanced framing while working on building his first OVE home. Based on the experience, there are some facets of advanced framing that the school will adopt as standard practice, but others it will likely avoid.
“In line framing is pretty simple, makes the design process easier and takes some of the guesswork out of the framing job, since we simply put the details on the plans,” said Dodson. On the other hand, he said he found fastening the exterior trim to the header hangers complicated and will not be using them on the next house. “There’s a lot going on there with the metal plates and the pan flashing,” he said. “They were a bit of a struggle.”
Other techniques that won’t become part of the crew’s standard practice, according to Dodson, include single top plates and 2x4 framing. Single top plates, when combined with 92.5-inch pre-cut studs, created the need for trimming every piece of drywall. Using free student labor, “it’s just a time issue for us, but it would be a big cost issue on a regular job site,” says Dodson.
Researchers also discovered the power of perceptions, whether well-founded or not. For example, the school installed 16-inch on center floor framing under kitchens and baths based on the advice of its tile installers, despite the availability of industry-approved guidelines for tile installation over 24-inch on center joists.
Regardless of the hurdles encountered during this first green project, the builder is eager to begin its second green home, which will employ many OVE framing practices — such as in-line framing, ladder blocking and two-stud corners—and be rated according to the National Green Building Standard.
To learn more about the student-built project, visit the Research Center’s technical ToolBase Services Web site.
For more information about energy efficiency, zero energy homes or joining the NAHB Research Center's Building America team, contact The Research Center online or call 800-638-8556.