The challenge in residential wood-frame construction is to construct dwellings that are
not only strong and resistant to the forces of nature, but also dwellings which are more energy efficient than in the past. Add to the mix increasingly stringent design parameters with ever changing energy conservation requirements and the challenge can become difficult. One means to overcome these challenges begins with the framing design which results in an energy efficient structure without relying as heavily on the addition of energy upgrades. There are framing techniques which are recognized in the International Residential Code (IRC) and reduce the carbon footprint of a structure while significantly diminishing energy use over the life of the dwelling. These techniques are packaged in the form of Optimum Value Engineering (OVE) or advanced framing.
Advanced framing incorporates code permitted lumber saving measures coupled with engineered design and energy savings opportunities that are not afforded by conventional framing alone. Not only is less lumber used in advanced framing, thermal bridging is minimized and more insulation can be used in the thermal envelope. Advanced framing may not be feasible for every builder in every situation; nonetheless, the benefits are well worth the due diligence to investigate.
Some Advanced Framing Techniques Include:
24” stud spacing is used throughout unless otherwise required for load transfer.
2” x 6” studs may be used in all exterior walls, knee walls, attic (hot) walls, etc. for increased R-value.
Single top plates are used throughout.
Single studs are used in lieu of double studs to support roof bracing. (hips, ridges, valleys)
Ceiling joists and rafters center over studs with 1” variance permitted.
Ladder blocking is used instead of a traditional 3-stud box at exterior wall intersections to accommodate additional insulation and reduce thermal bridging.
2-stud corners (California corners) are used at exterior wall corners for the same reasons as above.
Exterior headers are configured in a “C” shape so voids may be insulated.
Traditional interior door headers are replaced with single 2” x 4” nailers in non-load-bearing areas.
Interior load-bearing headers are fashioned in an “I” shape, where the top plate serves as part of the header and less lumber is used in the process.
Trimmers and cripples are omitted where not required for bearing or load transfer.
The benefits and potential cost savings of advanced framing do not come without extra effort, planning and oversight:
Approval must be obtained from the Building Official or Building Department if advanced framing has not been previously approved in a particular jurisdiction.
Engineered design of headers and wall bracing is likely to be required and may involve additional hardware.
Framing contractors and field staff must be re-trained.
Greater attention to detail must be given to the overall frame process with nailing patterns, load transfer, header design, etc.
Metal splice plates with specific nail patterns must be used to join single top plates at perpendicular wall intersections.
Butt joints occurring in top plates between studs must be blocked and properly nailed.
To help determine if advanced framing works for a particular business model one should consider a number of additional factors including: the current and future mindset of the prospective buyer, the lumber cost savings, the anticipated increase in energy performance, the feasibility of advanced framing in complex structures, and other factors. A great place to start is with the lumber estimator and the Energy Star Rater to do a plan-to-plan comparison between conventional and advanced framing.
Enjoy the challenges and savings of advanced framing.