Lack of research and design information for the seismic performance of balloon-type CLT shear walls prevents CLT from being used as an acceptable solution to resist seismic loads in balloon-type mass-timber buildings. To quantify the performance of balloon-type CLT structures subjected to lateral loads and create the research background for future code implementation of balloon-type CLT systems in CSA O86 and NBCC, FPInnovations initiated a project to determine the behaviour of balloon-type CLT construction. A series of tests on balloon-type CLT walls and connections used in these walls were conducted. Analytical models were developed based on engineering principles and basic mechanics to predict the deflection and resistance of the balloon-type CLT shear walls. This report covers the work related to development of the analytical models and the tests on balloon-type CLT walls that the models were verified against.
The goal of this work was to develop material quantity estimates of a typical mid-rise office building in the Pacific Northwest and to deliver the results to the Forestry Research Team in the University of Washington (UW) College of the Environment School of Environmental and Forest Sciences. The Forestry Research Team will then use these results to develop regionally specific life cycle inventory data to support the greater study funded by the 2015 McIntire-Stennis Research Grant, which is “to assist small and medium-sized wood products companies and Native American tribal enterprises to understand and adapt to changing market conditions” (http://depts.washington.edu/sefsifr/2015-mcintire-stennis-grantwinners/).
This report explores the building code related considerations of wood construction for school buildings that are up to four storeys in height. Though wood construction offers a viable structural material option for these buildings, the British Columbia Building Code (BCBC 2018) currently limits schools comprised of wood construction to a maximum of two storeys. Three- and four-storey schools and larger floor areas in wood construction require an Alternative Solution.
The report identifies key fire safety features offered by combustible construction materials including tested and currently widely available engineered mass timber products, such as glued-laminated timber and cross-laminated timber. A risk analysis identifies the risk areas defined by the objectives of the British Columbia Building Code (BCBC 2018) and evaluates the level of performance of the Building Code solutions for assembly occupancies vis-à-vis the level of performance offered by the proposed schools up to four storeys in building height.
As land values continue to rise, particularly in higher-density urban environments, schools with smaller footprints will become increasingly more necessary to satisfy enrollment demands. There are currently a number of planned new school projects throughout British Columbia that anticipate requiring either three-or four-storey buildings, and it is forecasted that the demand for school buildings of this size will continue to rise.
This report is closely related to the study Design Options for Three-and Four-Storey Wood School Buildings in British Columbia, which illustrates the range of possible timber construction approaches for school buildings that are up to four storeys in height.
Mass timber and CLT construction offers many advantages, such as enhanced modularity, reduced construction schedules, improved thermal performance, and material sustainability. However, mass timber’s propensity to absorb moisture from the environment and the relative vapor impermeability of CLT panels introduces unique challenges when incorporated with the building enclosure. These challenges should be considered during design and construction phases to ensure long-term performance.
The VaproShield Mass Timber Building Enclosure Design Guideline covers the best practices for the design and construction of high-performance CLT wall and roof assemblies. RDH is the principal author and editor of the guide and within its capacity, we do not purport to endorse any specific material or technical matter within this guide.