| R.J. Burnside & Associates Ltd. Robert R. Marshall
In Canada, building rehabilitation for roofing and wall system repairs and replacement cost an estimated $7.5 billion annually. A conservative estimate of the premature failure rate is 3 to 5 per cent, or $225 to $375 million per year. Premature failure is defined as any performance condition requiring repair or replacement of the system before the benchmark date. The building envelope was identified as particularly vulnerable to durability problems.
Exposure to costly failures is significant for building owners, home warranty programs, insurance companies and builders. For example, high-rise condominium claims were estimated to be about $20 million in 1990 for Ontario. A 2000 report for the Greater Toronto Area (GTA) found that claims are common in the first few years of a building's life, with the majority occurring in the first five years, as shown in figure 1. A high incidence of failures in British Columbia led to the insolvency of the BC and Yukon New Home Warranty Program. In the United States, the Home Owners Warranty Program became insolvent in the early 1990s due in part to substantial foundation failures. Risk management techniques are needed to reduce premature failure.
Figure 1. Average percentage of claims due to building defects
Period Per period Cumulative
Within 1 year 15% 15%
Within 1 - 3 years 15% 30%
Within 3 - 5 years 40% 70%
Within 5 - 7 years 25% 95%
Within 7 - 10 years 3% 98%
Within 10 - 15 years 2% 100%
Canada Mortgage and Housing Corporation (CMHC) and the Ontario New Home Warranty Program (ONHWP) had undertaken a study in 1990 to document and evaluate the incidence and magnitude of failures in 44 buildings. The findings were published by CMHC in a 1991 report, Construction Problems in Multi-Family Residential Buildings (http://www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/ 90230.htm). | 