Case Study: Envelope Failures in Multi-Unit Residential Buildings in the Pacific Northwest

​Over the past two decades, market forces have driven a surge in multi-unit residential building construction and conversion projects in the coastal areas of the Pacific Northwest from southern British Columbia down to areas of northern California.

Concurrent with this construction trend, the Pacific Northwest building industry has been plagued by an increased incidence and impact of envelope failures. Envelope failures in the Pacific Northwest have typically led to deterioration of a building’s structure by rot or biological growth through exterior water penetration into the building assembly.

The recent series of envelope failures has severely impacted the performance and durability of multi-unit residential building construction and resulted in numerous lawsuits and premature rehabilitations.

The intent of this paper is to explore the factors contributing to the recent prevalence of envelope failures in the Pacific Northwest, review the consequences of the building envelope problems and how they were diagnosed, examine the reactions and responses from local legislatures and provide important considerations for developers, designers and contractors to consider in order to avoid such problems in the future.