Last week’s post on "Thermal Bridging" kicked off a series of articles that I have wanted to share for a long time. These articles cover issues, techniques and solutions related to how we build exterior walls and the impact of some of those decisions. Today’s article is about one of the solutions to minimize "Thermal Bridging" through Advanced Framing Techniques. What we know today as "Advanced Framing Techniques", was originally developed in the 1960’s as Optimum-value engineering (OVE) framing techniques under a Housing and Urban Development (HUD) initiative to cut the cost of houses by omitting unnecessary lumber. The approaches did not get widely adopted at the time. However, with the passage of time, many of the original OVE techniques have been incorporated in what we today refer to as "advanced framing". Advanced Framing includes OVE framing techniques such as increasing joist, stud, and rafter spacing to 24 in.; placing doors and windows on stud layout; and using stacked framing for direct load transfer. Application of advanced framing not only saves on lumber and labor costs, but also supports better insulation detailing and reduces the occurrence of drywall cracking. The image below illustrates some of the advanced framing techniques. 
Advanced framing, as the name implies, means using framing lumber intelligently in wood framing by: 1. use of common material dimensions (24-inch grid) as a basis for design to maximize material use and minimize waste and 2. efficient load transfer to reduce unnecessary framing members from the home. As you can see in the illustration above, some of the techniques used include stack framing – allowing for the use of single top plates, elimination of wood beams/headers in non-load bearing walls, and two-stud corners. Framing around openings in exterior walls limited to those framing members needed for vertical load transfer or horizontal load resistance. Looking at this from a broader view – what does this do for our exterior wall assembly and my house in general? Well… besides cutting back on material waste and material usage – which increases resource efficiency, one of the main goals of green building – incorporating these techniques allows us to install more insulation in exterior walls. In simple terms: Advanced framing actually replaces lumber with insulation material and maximizes the wall that’s insulated, which improves the whole-wall thermal resistance or R-value. So let’s look at a comparison of R-values in a standard wall vs a wall constructed with advanced framing: A standard wall assembly using R-13 batt insulation will have an effective R-value of 11.1. An "advanced" wall assembly will have an effective R-value of 14.6 or 30% higher than the traditional wall. If you’re a homeowner, you’re probably reading this going: "How does this affect my wallet?" – I have some simple stats for you. Fully incorporating advanced framing techniques may result in:
- Materials cost savings of about $500 or $1000 (for a 1,200- and 2,400-square-foot house, respectively)
- Labor cost savings of between 3% and 5%
- Annual heating and cooling cost savings of up to 5%.
(Source & detailed calculation: http://www.energysavers.gov ) So if you are currently in the market shopping for a home, ask if the home you’re considering was built using advanced framing techniques or with other systems like SIPs or ICFs – which I will cover in future articles. If you are in the process of building a new home or undertaking a major renovation, ask your builder to incorporate these techniques. You will end up with a better home. Links to other articles in this series: Thermal Bridging… and how it affects a wall assembly – Part1 of 7 Sources: http://www.buildingscience.com http://www.toolbase.org http://resourcecenter.pnl.gov http://www.energysavers.gov
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