Mass Timber Modular Construction: Developments in Oregon

Abstract

With the mass timber industry taking off in 2015 in Oregon, when DR Johnson Lumber in Riddle, OR started producing CLT panels, government officials were eager to support it for its promise of economic development in rural communities and also had hopes of addressing the state’s affordable housing crisis using mass timber modular construction. While mass timber modular housing has had some success in Europe, the different construction standards and building culture in the United States make it more challenging. With few areas in Oregon in which housing is likely to be built over six stories tall or in large-scale developments, it did not seem possible that mass timber could solve the affordable housing crisis where it cannot compete in cost with standard light wood-frame construction. However, it did seem feasible that mass timber panels, which are so well-suited to customizable pre-fabrication through digital manufacturing, might be successful in an alternative building type for modular construction: classrooms. In successful models of mass timber modular classrooms in Austria and Germany, schools were built in much shorter timeframes and for 25% less cost than steel or concrete construction. The authors are now working with a modular building manufacturer in Oregon, Modern Building Systems (MBS), that produces custom-designed modular light wood-frame classrooms. While mass timber classrooms cannot compete in price with light wood-frame, particularly in single-story applications, they could be competitive for two story (or taller) schools, which are usually built using steel braced-frame and concrete block. Because MBS is 18 miles west of Freres Lumber, which is newly producing Mass Plywood Panels (MPP), and the MBS facility needs no modifications to use MPP instead of wood-frame, the authors are working with them to design an economically competitive mass timber module, with several potential clients interested in testing a prototype in 2019.