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Constructed during WWII, Hangar 1 is one of five identical, timber Warren truss structures located at Canadian Forces Base St-Jean. Currently, the Department of National Defence has arbitrarily mandated that these heritage structures (base/province-wide) be evacuated during excessive snow events exceeding 10 cm due to potential serviceability and/or structural capacity issues. An automatic total station, as part of a larger Structural Health Monitoring program, was installed to capture three-dimensional deflections at 18 locations throughout the structure continuously, in real-time, to develop a staged decision-making process, serve as an early warning system (if evacuations are indeed warranted), and to confirm that it is an effective monitoring solution in the long-term. The ATS observed maximum member deflections, far below calculated limits, during a 35 cm snow load event, thus revealing that the evacuations are unwarranted based on the prescribed evacuation criteria. Thus, it is hypothesized that observed damages and poor building performance are due to other factors that require further investigations. Overall, the ATS was effective in a long-term, real-time, timber-monitoring program designed for knowledge and emergency purposes, as alert notifications were successfully sent to building occupants. The design/implementation of the integrated staged alarm system, highlighted capabilities/limitations of the ATS, and future considerations for employing an ATS in similar long-term timber monitoring projects involving heritage structures are thoroughly presented within this paper. [ABSTRACT FROM AUTHOR]