Waterdown Library - The Critical Role of Transition Membranes in Building Envelope Performance

March 11, 2026 12:00 PM - 01:00 PM

Many modern buildings incorporate multiple envelope systems that rely on different trades working together. When these assemblies are not properly connected, even a well-designed building can experience performance failures. At the Waterdown Library, this challenge became evident when the interface between the roof and curtain wall assembly began leaking shortly after construction. The two systems were installed by independent Contractors and did not consider their counter parts' work and resulted in a weak point in the assembly. This weak point did not last very long and resulted in water migrating into the building, running along the glazing and mullions.

MTE was brought in after the warranty period, when unresolved leakage and the loss of the original contractor left the City responsible for repairs. Through intrusive investigation, it became clear that the issue was not a product failure, but a coordination and detail failure.

This presentation will walk through the investigation findings and demonstrate how reinstating a continuous transition membrane resolved the issue. Attendees will gain insight into how proper trade coordination and detailing at system interfaces can prevent costly failures in new construction.

Andy Xiao, P .Eng., RRO 

MTE Consultants

Andy is dedicated to client success and specializes in solving complex building restoration challenges. With more than 10 years of experience, he has managed a wide range of projects­from large portfolio programs to targeted repair work, while maintaining a strong focus on budget and practical results. His broad technical knowledge across building envelope and restoration disciplines allows him to deliver solutions that perform over time. Andy believes successful restoration comes from understanding how buildings function and anticipating how repairs will perform in the long run. 

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