The Pros and Cons of Advanced Framing
Optimum value engineering (OVE) can same money, time, materials, and energy — but is it worth the hassle?
Advanced framingHouse-framing techniques in which lumber use is optimized, saving material and improving the energy performance of the building envelope., also called optimum value engineering (OVE), is a framing system that aims to pare the amount of lumber used to frame buildings to the bare minimum. Advanced framing was developed in the 1960s by the Department of Housing and Urban Development as a way for builders to reduce costs.
In recent years, the decades-old framing system has been adopted by many green builders. These new advanced framing devotees are focused less on the cost-cutting aspects of the framing system than on its other virtues, including energy and materials savings.
How advanced framing saves lumber
If you want to adopt every principle of advanced framing, here’s what you need to do:
- Design your house with dimensions that fit a 2-ft. module.
- Switch from 16-in.-on-center framing to 24-in.-on-center framing for joists, studs, and rafters.
- Stack the wall, floor, and roof framing so that rafters, studs, and joists all line up.
- Switch from double top plates to single top plates joined with steel strapping or splice plates.
- Get rid of jack studs; instead, support headers with steel clips (Simpson HH header hangers).
- Omit headers on gable walls and other non-loadbearing walls, and make sure headers are right-sized.
- Switch from three-stud corners to two-stud corners with drywall clipsMetal or plastic stops that are attached to framing at inside corners. The clips replace framing, thus leaving more room for insulation. Because such a corner floats (acting as a stop, the clip allows the first sheet of drywall to be trapped by the second, perpendicularly installed sheet), cracking of the drywall joint is less common..
- Use ladder blocking at partition intersections.
- In some cases, omit structural wall sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. and substitute T-profile diagonal steel bracing.
Will your local code official balk?
Even though optimum value engineering has been around for decades, that doesn’t mean your local code official won’t raise his eyebrows. As one advanced framing guide puts it, these details “are likely to inspire questions from the building official.” So it’s best to discuss your plans with your local officials before you begin framing.
The International Residential Code (IRCInternational Residential Code. The one- and two-family dwelling model building code copyrighted by the International Code Council. The IRC is meant to be a stand-alone code compatible with the three national building codes—the Building Officials and Code Administrators (BOCA) National code, the Southern Building Code Congress International (SBCCI) code and the International Conference of Building Officials (ICBO) code.) now recognizes some, but not all, advanced framing details. For example, Figure R602.3(3) of the 2006 IRC allows the use of drywall clips at two-stud corners. Section R602.3.2 of the 2006 IRC allows single top plates, as long as joints are spanned by “a minimum 3-inch-by-6-inch by 0.036-inch thick galvanized steel plate that is nailed to each wall or segment of wall by six 8d nails on each side.”
If you are building in a seismic zone or a high-wind zone, however, many advanced framing details won’t fly with your local official.
Taking baby steps
Although advanced framing is often presented as a package of measures, some builders prefer to adopt some, but not all, advanced framing details.
For example, 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.
Builders in love with advanced framing cite the following advantages:
…and a few disadvantages
Let’s face it — advanced framing isn’t all apple pie and ice cream, or everyone would have adopted the system years ago. Here are a few disadvantages of advanced framing:
- Your design costs (and perhaps your engineering costs) are likely to be higher.
- You’ll need to invest more planning time and produce more accurate drawings.
- Your local code officials may balk at some of your details, so you’ll need to budget time to negotiate with your building inspector.
- If your framers are unfamiliar with optimum value engineering, they’ll need to be trained.
- If you have to seek out a framing crew with advanced framing experience, your labor costs may actually be higher.
- As your framing crew works through the early phase of the learning curve, their productivity will drop.
- Supervision costs may increase, because someone needs to ensure that in-line framing and other advanced framing details are implemented properly.
- Any savings in lumber costs will be partially offset by added costs for steel splice plates, drywall clips, header hangers, thicker subflooring, and in some cases deeper floor joists.
- Using a single top plate means that you’ll no longer be able to use standard precut studs — you’ll have to buy longer studs.
- Customers may perceive advanced framing techniques as inferior or substandard, because less lumber is used.
- Some siding types, including vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). siding, require 16-in.-on center fastening, and are therefore incompatible with 24-in.-on-center framing.
- Without jack studs, it’s harder to fasten siding or trim near windows and doors, because there’s less framing to nail to.
- Energy savings are small; according to one source, advanced framing techniques changed a home’s whole-wall R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. from 16.2 to only 17.2.
For real energy savings, you need more than OVE
Some advanced framing advocates take credit for the advantages of foam sheathing, implying that the use of foam sheathing is part and parcel of the advanced framing package. In fact, what type of sheathing you specify is independent of your framing details.
The use of foam sheathing is by no means restricted to those using advanced framing. Plenty of builders who use foam sheathing are old-fashioned two-top-plate framers who love to throw a few extra studs in their walls.
If you’re interested in improving the thermal performance of your wall, removing a few studs helps — but not much. To really make a performance leap, you need to interrupt all of the thermal bridging, and to do that, you either need exterior foam sheathing (with or without advanced framing) or a double-stud wallConstruction system in which two layers of studs are used to provide a thicker-than-normal wall system so that a lot of insulation can be installed; the two walls are often separated by several inches to reduce thermal bridging through the studs and to provide additional space for insulation..
Because the thermal benefits of advanced framing are relatively minor, many builders have concluded that the small savings in materials and energy use aren’t worth the hassle and extra supervision required to make it happen.
Switching from 2x4 walls to 2x6 walls
For builders working in regions of the country where 2x4 walls are still common, adoption of Advanced Framing techniques usually means upgrading from 2x4 walls to 2x6 walls.
The significant improvement in whole-wall R-value seen by these builders is due to two factors: their walls are now thicker, and their walls have fewer framing members (and therefore a lower framing factor). If they also take the opportunity to add foam sheathing, this package of measures — moving from 2x4s to 2x6s, adding foam sheathing, and adopting Advanced Framing techniques — can make a real difference in wall performance.
Last week’s blog: “Foam Under Footings.”
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