TORONTO, Feb. 15, 2013 /CNW/ - The Institute for Catastrophic Loss Reduction (ICLR) today released a study on urban flooding in Canada which looks at, among other topics, interpretation of building and plumbing code wordings that relate to installation of backwater valves to protect homes from sewer backup. While a significant amount of research by ICLR and others has concluded that resolution of building code enforcement issues may result in reduced vulnerability to extreme natural hazards, issues surrounding code interpretation have not previously been studied.
Urban flood damages are a recurrent and growing issue for municipalities, insurers and homeowners across Canada. Damages from urban flood events often total in the $10s- and $100s of millions of dollars. In May, 2012, a storm system that affected Thunder Bay and moved through to Montréal resulted in $260 million in insured damages. In July, 2012, a storm moved through southern Ontario affecting several neighbourhoods in Hamilton and Ottawa, resulting in $90 million in insured damages. An extreme rainfall event that affected a large region of southern Ontario from Hamilton to Durham Region in August, 2005 resulted in over $500 million in insured damages, $247 million of which was associated with sewer backup. Also in 2005, heavy rainfall and associated flooding resulted in $300 million in insured damages in southern Alberta. A severe storm in Edmonton, Alberta in 2004 resulted in approximately $166 million in insured damages, $143 million of which were associated with sewer backup.
Previous research conducted by ICLR revealed that a mainline, full port, normally open backwater valve, when properly installed and maintained, in tandem with the severance of foundation drains (i.e. weeping tile) from the sanitary sewer, is one of the best measures a homeowner can take to reduce the risk of stormwater and/or sewage backing up into a basement. But building code/plumbing code and/or local by-law requirements to install such valves in new homes is spotty across the country, largely owing to code interpretation.