Revision of building codes may be required after tornado

An on-the-ground inspection of damage done to homes following several tornadoes that hit Ontario on Aug. 20, 2009 prompted engineers from the University of Western Ontario to question whether or not Canadian building codes required changes.

Gregory Kopp, a researcher at the University of Western Ontario, was one of a handful of specialists on-site after the tornado hit in the Woodbridge, Maple and Vaughan area of southern Ontario in late August.

Just after the severe storms, most of the media attention focused on whether or not materials used in the construction of the 35 to 40-year-old subdivisions were sufficient. After careful and precise on-site investigations, Kopp and his team did not consider the building materials to be insufficient (or not strong enough). However, Kopp did say that the methods used to secure roofs to wall structures could have been a significant factor in the damage sustained by many houses during the tornadoes.

Through the onsite investigation Kopp and his team found that many nails used to secure sheets to the rafters or rafters to the walls had missed their mark. Given the internal pressure tornado-winds can cause on a building any breach of the structure—such as a board working loose because it is not securely fastened—can prompt significant change in the internal pressure of the house and prompt significant damage, such as blown out windows, roofs torn off, rafters ripped out and wall collapses. Also, this debris can puncture other homes in the area, setting the cycle in motion.

After his presentation, Kopp was clear that the current problem could be easily averted: Keeping the roof on a house could be as simple as using hurricane braces, a relatively inexpensive fix, to make sure the roofs of newly built homes can withstand high wind speeds.

While the damage in Vaughan and environs was to houses built to code, Kopp also suggested that an examination of current codes, and possibly updating these codes, was not out of the realm of possibility.

“It’s amazing not more people were injured or killed,” said Kopp, during his presentation, which was organized by the Institute for Catastrophic Loss Reduction (ICLR) and hosted in Swiss Re’s office in Toronto.

It is now presumed that two F2 tornadoes, packing wind speeds of between 180 and 240 km/h, hit the Vaughan/Woodbridge and Maple area on Aug. 20, 2009. Depending on further investigation, Kopp and his team may upgrade one of these tornados to an F3.

As a result of the investigation, Paul Kovacs, executive director of ICLR, stated that the P&C industry could help by sharing their research and information about tornado damage to help improve municipal building codes.

Kovacs also mentioned that Canada may consider following the U.S. lead, where the P&C industry have started to rate communities on how well their building codes are enforced.

Originally published in Canadian Insurance Business Magazine in September 2009

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