Gems of Innovation: Sage Green innovates with “ply-on-foam” wall assembly
Ben Walsh of Green One Construction built “Sage Green” a townhome development in Beaverton, OR, it's five net-zero energy homes built using the unique “Martha Wall” ply-on-foam wall assembly, to achieve 40% more energy efficiency than standard construction (R-33). With a goal of affordability, they used least cost and familiar 2x8 wood construction, a near-standard framing technique that made their assembly cost-effective and familiar to the framing contractors they used on the project. But instead of nailing the “shear wall” plywood sheathing directly to the framing members, they sandwiched a 1-1/4” Type II EPS rigid foam insulation between the plywood and framing to create a “thermal break shear” wall for increased efficiency. Surprisingly, this also made the wall just as strong (shear strength) and several times more flexible (seismic tolerance), as confirmed by testing data from Oregon State University’s Knudson Wood Engineering Laboratory in Corvallis, Oregon. This testing helped them gain approval for an innovation not covered by existing codes. Walsh wants more builders to use his and Martha’s innovation: “For less than 50 cents more per square foot, every new stick-built home could have walls that are 40% more efficient and seismically superior.” We hope to document both this project and The Martha Wall in the Code Innovations Database in 2016, and are seeking a donor who will underwrite these case studies to make it possible.