Initially intended to trim lumber and labor costs by reducing the amount of lumber without sacrificing structural integrity, advanced framing practices are now promoted as a key method to improve a home's insulation potential and thermal performance. One example is the three-stud corner, which eliminates one stud from a typical four-stud framed corner design.
The layout of the three studs–and, more recently, the advent of a two-stud configuration popularly called an open-stud or "California" corner–creates a cavity for insulation where none existed before. The result mitigates the thermal conductivity of a wood-framed corner in favor of a thermal break ...and a better-insulated house.
A three-stud corner is almost intuitive to a framer, requiring no different materials and only a slight change in application. But a two-stud design is trickier and requires an extra step that often foils the timesaving promise of advanced framing.
The central issue is attaching the drywall at the corner. While one stud of a two-stud corner aligns with the run of studs along one wall, there is no corresponding corner stud on the perpendicular wall, and therefore no surface to attach the edge of the drywall panel at that corner.
The most commonly quoted fix for this problem is to install metal drywall clips (or "stops") along the edge of the drywall panel that will meet the corner; the clips are then fastened to the single wall stud to secure the drywall. Drywall clips work well enough, and are readily available off the shelf, but they can be confounding and time-consuming to install properly.
Another solution is to fasten small pieces of scrap lumber (or blocks) up the backside of the single corner wall stud, creating a "ladder" of nailing surfaces for the edge of the drywall panel.
Though this technique uses up some wood scrap that might otherwise go to the landfill, it takes time to attach multiple, small blocks and requires some planning to make sure the attached scraps are aligned to meet the code-prescribed nailing pattern for securing drywall.
"Drywall clips and ladder blocking are a pain," says Guy Haskell, a semi-custom builder in Bountiful, Utah, who has been doing advanced framing for 15 years. "And they don't provide a full nailing surface."
Haskell's own technique calls for air-stapling full-length strips of scrap roof sheathing along the entire height of the single wall stud to provide a continuous nailing surface for the edge of the opposite-wall gypsum panel. And because sheathing panel strips are thinner than 2x6 blocks, Haskell has a slightly larger wall-corner cavity to insulate. "It eliminates virtually all of the heat lost at the corner," he says.
Another possible option, if one that would require a variance by the local code authority, is to fill the wall cavity to the corner with an expanding-foam insulation that is then screeded–scraped down–until it is flush to the inside wall plane.
When cured, the insulation creates a solid block that could sufficiently back up a drywall panel (if not serve as a fastening surface), especially if the drywall panel is fastened to the top and bottom plates and held at the corner with metal corner bead.
Tradeoffs for Dealers
By definition, advanced framing practices like the California Corner reduce the number of studs and other commodity components used to build a structural frame.
At a glance, that might appear to be cutting into a dealer's sales and inventory turns. But counseling builders and framers to employ advanced framing practices may very well boost overall profitability.
A key reason why is that advanced framing for better thermal performance is based on 2x6 frame construction at 19.2 and 24 inches on center rather than 2x4s installed at 16 inches on center. Advanced framing also advocates the use of engineered structural lumber, such as I-joists and glulams, as stronger and more reliable alternatives to sawn lumber. Engineered components typically carry a higher profit margin than their commodity counterparts, boosting the sale.
And don't forget about the value of consultative and cross-selling. A dealer well-versed in advanced framing and with insulation and air-sealing products on the shelves not only can balance fewer sticks with more batt or blow-in fiberglass, but also provide pros with solid advice for improving the thermal performance of their new homes. In turn, that can help a builder qualify for green certification and market lower monthly energy bills to potential homebuyers.
Learn More For more information about advanced framing, go to the online Toolbase Services provided by the NAHB Research Center at www.toolbase.org and search within the "Construction Methods: Wood Framing" category.
Caveat Advanced framing practices and specifically the use of two- and three-stud corners may not be allowed in high wind and seismic areas. Consult your local code authority for confirmation and any other limitations.
–Rich Binsacca is a contributing editor to ProSales.