Light-frame versus timber frame : a study in quantifying the differences

Graduation date: 2014The objective of this study was to compare light wood framing and traditional timber\ud framing quantitatively through environmental impact assessment and load path analysis. This\ud research was inspired by a traditional timber frame structure constructed in Vermont in 2011, and\ud the design of structures considered within reflect the general characteristics of this building with\ud some modifications. A light-frame structure was designed for comparison purposes to be\ud equivalent to the timber frame structure in overall dimension and function.\ud Cradle-to-gate environmental impact assessments were performed with the Athena\ud Impact Estimator for Buildings software, following the standard methodology of life cycle\ud assessment. The environmental impacts for each structural system as well as for multiple\ud material substitutions to each were investigated. Environmental impacts considered included\ud total energy use, fossil fuel consumption, global warming potential, and wood fiber use. Results\ud show that though the timber frame structure has more potential for decreased environmental\ud impact, these measures are driven largely by material choice.\ud Models for each framing system (light-frame and timber frame) were created using\ud SAP2000 structural analysis software, and load paths generated by applied design loads were\ud investigated and compared. Both structures were modeled with and without openings (doors and\ud windows), and comparisons were made based on resistance to uplift, story drift and twisting, the\ud addition of large openings, a break in load path, and the relative ranges of axial loads in posts and\ud studs. Results show that the timber frame structure outperforms the light-frame structure in many\ud aspects, providing increased resistance to uplift, story drift, and twisting, less sensitivity to the\ud addition of large openings or the loss of a floor-supporting post, and less variability in axial\ud forces in vertical members