Advanced Framing: Less Lumber, Better Houses
The whole point of advanced framing, also known as optimum value engineering (OVE), is to frame a house so that it meets its structural requirements without wasting material. Through advanced framing, you can eliminate up to 40% of framing lumber in a normal home, which is a big deal right now with lumber prices at all-time highs.
A welcome corollary is that the same house will have more room for insulation inside the walls and will therefore be more energy efficient than a conventionally framed house.
Advanced framing boils down to five steps:
1. Framing walls with 2x6s or 2x8s on 24-inch centers rather than every 16 inches can save a lot of wood and increase the energy performance of a house because it makes more room for insulation.
2. Stack the framing so that roof rafters or trusses align with wall studs and floor joists, creating a continuous load path from the roof all the way to the foundation.
Aligning framing members between floors transfers loads efficiently. This means that you can omit the double top plate in favor of a single one. It also means a better quality nailing job of the plywood that spans these transitions.
3. Place doors and windows on the grid.
Moving door and window openings so that they line up on the 2-foot grid reduces waste and, again, leaves more room for insulation.
4. Use less wood in the corners
Exterior corners can do well with fewer studs and more insulation in them. Equally, where interior partition walls meet exterior walls – less wood, more insulation.
5. Omit unnecessary headers - this is a big one that even seasoned builders that should know better don’t seem to understand.
Walls that don’t carry roof loads – for example, most gable-end walls – don’t require structural headers over windows or doors.
Transitioning to advanced framing
Although advanced framing is often presented as a package of measures, some builders prefer to adopt some, but not all, advanced framing details. Some builders who quickly adopt two-stud corners still retain double top plates, preferring to tie partition walls to exterior walls in the traditional way. Others are happy to switch to single top plates but prefer 16-inch-on-center stud spacing, because it permits more closely spaced nailing for siding.
It takes time and attention to learn how to frame a house in a new way, but the material savings can be big and the energy performance of the house can be much improved.
Design with materials in mind
When I design, I am always considering how materials will be used, and how to optimize usage to reduce waste.
Plywood and oriented strand board (OSB) come in 2-foot increments, so why not plan for that in building dimensions? Research conducted by the National Association of Home Builders Research Center on this optimum value engineering concept revealed mixed results for floor plans done on 2-foot increments. However, adjusting roof pitches/overhang dimensions to 2-foot increments significantly and consistently reduced materials and waste.
Some siding isn’t compatible with 24-inch on center stud spacing. For example, the Vinyl Siding Institute requires that most types of vinyl siding be installed with fasteners spaced no more than 16 inches apart; fasteners must penetrate studs. The Institute’s standard notes, “These distances may be increased if the manufacturer permits greater spacing based on wind load testing.”
Planning for advanced framing can be challenging
Design preferences about the appearance and layout of a home can conflict with the goal of reducing the number of necessary framing members. This makes it really critical to consider optimizing framing material as early as possible in the design process, and to repeat that goal frequently. (Like many other design considerations, advanced framing is most successfully accommodated if it is part of the design, not an afterthought.)
The smaller the home, the more challenging it can be to use advanced framing techniques. Focus on those that deliver the highest lumber savings, such as spacing of repetitive members (studs, joists, and rafters).
This article was adapted from Fine Homebuilding and Green Building Adviser’s website https://www.greenbuildingadvisor.com/article/the-pros-and-cons-of-advanced-framing