As a consultant and former contractor, I don’t have much influence on building designs and construction details. As I discussed in a previous post, Smart High-Performance Homes Start with Good Design, I am usually asked to make projects “green” after the design is mostly complete. I have plenty of ideas on how to create high-performance buildings, but do not see my clients implement them as often as I would like. In Georgia’s mixed-humid climate (Zone 3), this kind of construction is not that challenging but it is rare that I see a house or multifamily building conceived to be high performance from the start.
To create a truly high-performance house, my go-to concept is to simplify the volume. This supports a well-sealed building enclosure that keeps the interior dry and comfortable. Avoiding cantilevers, ceiling vaults and trays, dormers, and similar details makes construction easier to detail and allows a project team to get to high performance levels without breaking the bank.
About the foundation
My house is a good example of a simple volume. It’s on a slab with 1-in. XPS (R-5) under the first 2 ft. of perimeter. This is not code-mandated in my region, primarily due to the risk of termite damage but I addressed that issue by installing a vapor- and termite-barrier membrane over the entire slab.
For aesthetic reasons and to meet the local historic commission ban on slab-on-grade foundations, I installed a raised slab inside stem walls, creating a crawlspace-like look for the house. By not building an actual crawlspace, I eliminated the need for additional conditioning and dehumidification, as well as the potential for moisture intrusion from below.
Advanced framing for the walls
The walls are 2×6 at 24 in. on center, providing space for more insulation (R-22 blown fiberglass) as well as…
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