Rain Check

The recent history of multi-unit residential construction in Canada has not been a happy one. The “leaky condo” crisis in British Columbia is the most infamous case, with radio and television having a heyday featuring the unhappy victims. These were people who bought properties only to find them leaking, rotting and inhabitable after a few months. Damage claims have risen to over $1 billion, and the blame has fallen as much on engineers and architects as on the contractors.

But problems are not just confined to the West Coast. They were already so bad during the Ontario building boom of the early 1990s, the Ontario Home Warranty Program was inundated with $20 million worth of claims from condominium owners. Realizing that something must be drastically wrong with building practices, the Ontario organization asked Canada Mortgage and Housing Corporation to investigate.

Jacques Rousseau of CMHC in Ottawa explains that when they went to check out the different faulty buildings, they found one common denominator: wherever the problem appeared in the building, there was no detail drawing. Designers had thought that common building practice would suffice The trouble was that the contractors’ building practice had not kept up with advances in building science and materials. The studies found that it did not matter which type of building system was used, there were problems with them all.

To remedy the situation CMHC has started to issue Best Practice Guides containing model details, as well as general information and advice. We show here samples from two of the Best Practice Guides. The first, on page 52, is from Brick Veneer Concrete Masonry Unit Backing (i.e. brick facing, concrete block and a cavity). This is one of two guides prepared by Ashok Malhotra, P.Eng. of Halsall Associates’ Ottawa office with contributions by Otto, Bryden, Erskine Martel Architects, CMHC and Masonry Canada. Malhotra says that the detail shown of a slab/wall is one of the most common problem areas in buildings.

The two details opposite are from the newest guide which is intended to deal with the particular problems caused by the West Coast’s relatively wet and warm climate. The 259-page Wood-Frame Envelopes in the Coastal Climate of British Columbia was compiled with the help of consulting engineers RDH Building Engineering (David Ricketts P. Eng. in charge) and Morrison Hershfield. The latter’s study of the cause of problems in British Columbia won a Canadian Consulting Engineering award of excellence last year.

In addition to the two publications mentioned above, the corporation has issued guides on Brick Veneer Steel Stud, Flashings (also by Halsall Associates) and Wood Frame Envelopes. Jacques Rousseau says others in the works will be on Exterior Insulated Finishing Systems, Fire and Sound for Wood Construction, Precast Concrete, and Curtain Wall.

Rousseau stresses that the guides are done in partnership with industry and often at industry’s request. “This is not about CMHC coming down the mountain with the commandments,” he says.

The guides, available in English and French, include CAD details on CD-ROM. The CMHC web site is www.cmhc-schl.gc.ca. Tel. 1-800 668-2642.