There is a lot of talk in the U.S. these days about building envelope commissioning. It is the process of hiring a building envelope consultant to ensure that the enclosure is done right. It is new to Americans, but not to Canadians.

In our cold climate, envelope commissioning developed in the late 1980s, driven largely by Public Works Canada’s efforts to control humidity levels in its buildings. Moisture-related problems were cropping up as a result of buildings that had been heavily insulated during the 1970s energy crisis.

Ideally, a building envelope consultant collaborates at the conceptual design stage and sticks around to inspect installation, explains Mark Lawton, senior building science specialist of Morrison Hershfield Ltd.’s Vancouver office. The main objective is to achieve environmental separation and to ensure a building’s longevity and durability, although some builders are promoting it as a means of improving energy efficiency. The work involves air tightness and includes pressure resistance – the ability of the air barrier to stop wind loads.

While envelope commissioning is not new in Canada, it is uncommon in some regions and many builders have different notions of what it is. The city of Vancouver is on the leading edge of envelope commissioning, stemming from its history with leaky condos in the 1980s and 90s. Its building code (Vancouver Building Bylaw) requires building envelope professionals to review the design and inspect the construction of multi-residential frame structures. Furthermore, builders must have third party warranty coverage for building envelopes.

Unfortunately, what’s happening in Vancouver isn’t happening across Canada. In some cities building envelope consultants are not retained until the installation stage. At that point, fixing errors in a design can be expensive. “There’s a lot of cases where the plans (design) are wrong and they could have been improved at no extra cost,” if commissioning commenced during design, explains Laverne Dalgleish, principal, Winnipeg-based Building Professionals.

Dalgleish believes we need to create a “single definition” for envelope commissioning and it is up to the provinces to make a commitment to implementing mandatory legislation to ensure accountability. He notes that even in medieval times there were codes in place that imposed liability on builders whose structures underperformed and caused harm to occupants. Why should things be different today?

Unlike Vancouver, the city of Toronto doesn’t have a building code so there are no mandatory requirements for enclosure professionals. Building envelope consultants are sometimes retained at the design stage, but more often their jobs don’t start until a project is under construction, says Kevin Day of Halsall Associates Limited.

“It requires some level of review to check what was designed, and what the owners think they paid for, is in fact performing. The work might include insitu testing of walls/windows/roofing, thermographic scanning, and installing a monitoring system in key areas of the envelope where performance is critical.”

Quarterly site visits to measure localized temperatures of the building assembly and to identify condensation if thermal bridges are an issue can also be employed, he adds. A case in point was the dual-barrier roof system that Halsall designed for the Credit Valley Hospital in Mississauga. By monitoring the thermal efficiency of the membrane Halsall demonstrated that keeping the insulation dry in a protected membrane roof was more thermally efficient than a conventional protected membrane system, explains Day.

Both Dalgleish and Day agree that envelope commissioning is not widespread for many building types in Toronto or many parts of Canada outside of B.C. Day says he doesn’t expect to see rapid growth in the near future unless it becomes a popular LEED point for new building construction. (The Canada Green Building Council (CaGBC) has indicated it may add a LEED point).

Dalgleish says LEED would be good for the building envelope industry because some architectural and design firms go LEED “point crazy,” when designing buildings.

Regardless of what region you are in, Lawton says the quality of a building (including its envelope) is often dependent on whether the site superintendant makes sure that the right things get done. It is almost that simple. CWCJ