The California Energy Commission (CEC) has set a goal of net zero energy for residential buildings by 2020 and for commercial by 2030. The idea is to produce new projects with zero reliance on fossil fuel. It is not clear how this will be achieved, however it will likely require a combination of high energy efficiency and cogeneration of energy on site. One methodology to achieve high energy efficiency is the implementation of Advanced Framing.
Advanced framing (also known as “optimum value engineering” or OVE) was developed in the 1970s, but is capturing more and more attention lately as architects and builders look for ways to reduce homes’ energy usage and meet stricter energy codes. Advanced framing techniques optimize material usage to cut down on waste, eliminate redundancies, reduce labor, and increase a home’s energy efficiency, all while maintaining structural integrity.
APA-The Engineered Wood Association recently published a 24-page Advanced Framing Construction Guide that provides an overview of some of the techniques, including those that can be used toward Energy Star certification.
To ease the transition to new building methods, advanced framing can be implemented in stages. For example, here are four advanced framing techniques that can be adopted to increase cavity insulation and reduce thermal bridging, thereby providing overall higher whole-wall R-values.
1. 2x6 Framing Placed 24 Inches On-Center
Advanced framing methods increase member spacing, typically to 24 inches o.c., effectively trimming the number of required studs by about one-third. Walls built with 2x6 wood framing spaced 24 inches on center have deeper, wider insulation cavities than conventional 2x4 framing spaced 16 inches on center, thereby increasing the amount of insulation inside the wall and improving the whole-wall R-value.
Insulated corners eliminate the isolated cavity found in conventional three- or four-stud corners, making it easier to install insulation and providing for more cavity insulation space. Advanced framing wall corners can include insulated three-stud corners or two-stud corner junctions with ladder blocking, drywall clips, or an alternative means of supporting interior or exterior finish.
3. Ladder Junction Tee Intersections
Advanced framing ladder junctions are used at wall intersections with 2x blocking at 24-inch o.c. vertical spacing. This method requires less than 6 feet of blocking material in a typical 8-foot tall wall. In conventional walls, interior wall intersections include a stud at each side of the intersecting wall, which can require as much as 16 feet of stud lumber plus additional blocking material.
4. Insulated Headers
Advanced framing headers offer increased energy efficiency by replacing framing materials with space for cavity insulation inside the header. Advanced framing headers are sized for the loads they carry and are often installed in single plies rather than double. Wood structural panel box headers are another option to consider that maximize the insulatable cavity while providing the structural support via the wood structural panels that are already used on the exterior of the building.
For more information and diagrams on these and other advanced framing techniques, download APA’s Advanced Framing Construction Guide at www.apawood.org and see other resources at APA’s www.performancewalls.org. In addition, advanced framing CAD details can be downloaded at www.apacad.org.
KARYN BEEBE, P.E., LEED AP, is an APA Engineered Wood Specialist serving the Southwest. A licensed Professional Engineer in the state of California, Beebe graduated from Purdue University with a BS in Civil Engineering. Her duties include consulting with designers on the efficient specification of engineered wood products in construction. She is an active member of the Structural Engineers Association, the U.S. Green Building Council, and serves as Vice President for the San Diego Area Chapter of the ICC. Prior to joining APA, Beebe worked as a structural engineer and structural plan reviewer for the San Diego building department. Karyn can be reached at Karyn.firstname.lastname@example.org or 858-560-1298.