How Levels of Fabrication Precision Can Lead to Improved Quality in Light Frame Wood Construction

Wood is one of our most sustainable materials. It requires less energy to produce and deliver to the project location than steel, concrete, masonry, or other materials. Timber products sequester a significant amount of carbon in comparison to the amount of carbon expended during harvest, manufacture, and transport. Timber structures have generally performed well in earthquakes and wind storms if constructed according to the building codes and good construction practice. Timber structures often have a cost advantage over other types of structures. However, “sustainability” is not an “either/or” proposition. A sustainable material can become more sustainable or less sustainable depending on a number of factors. In wood construction, some methods or techniques of manufacture and construction are more sustainable than others. Wood is a sustainable material, and wood structures can be sustainable, but many of these advantages are lost when timber structures perform poorly, fail prematurely, or when the structure needs substantial repair or replacement early in its life cycle. The ASCE/SEI Committee on the Performance of Wood Structures has been charged with determining the controllable effects of material conditions, fabrication, and workmanship on the life-cycle performance of wood structure. The task has been broken into several portions: moisture effects, construction and fabrication, fire, and QA/QC methods. This part examines how fabrication and construction methods or techniques affect the overall performance of a wood structure. Better performance leads to a longer structural life, hence keeping the sequestered carbon bound for a longer period of time. If the useful lifespan of typical wood buildings is increased by reducing the number of defective buildings demolished, then the built wood infrastructure increases. Then the total sequestered carbon in all wood construction increases. This study examines fabrication practices include the effects of poor lumber storage, tolerances in fabrication and fit-up and the effects of assembly and construction error repairs, and how better practices can improve the sustainability of wood structures. These practices will also create a heightened expectation of sustainable wood construction quality and fabrication professionalism which could lead to sustainable wood being used for structures where steel or concrete would otherwise be employed. Lessons learned from these studies can lead to reduced defects in the future and to enhancing the sustainable nature of wood construction. This paper will broaden the knowledge of practicing engineers, preparing them for the challenges of the 21st century. It will assist them to be knowledgeable in factors affecting sustainability and to become better stewards of materials and the built environment.