Tornadoes are a common event in Canada. The most common sites of known tornado formation are all across the Prairie Provinces and also in Southern Ontario. The tornado season in Canada runs roughly from April through September with tornado formation peaking in the Summer months. While most tornadoes are on the lower-end of the wind speed scale, powerful F3 tornadoes occur about once every eight years in Southern Ontario, and F4 and the extremely powerful F5 tornadoes have been recorded in Canada (Environment Canada switched to the Enhanced-Fujita scale in 2013 – the old system is used here as it is deemed likely to be more familiar to users). In the event that a tornado strikes a home, there is a high chance that the roof will sustain damage or even be removed altogether. When a home is struck by a tornado, substantial uplifting forces are generated on the roof and the toenails that hold the roof to the roof rafters are often insufficiently strong to resist these forces, resulting in sections of the roof (or the entire roof) lifting of the house. In addition to damage directly to the home, these roof debris are then accelerated by the tornado to very high speeds and pose significant danger to people and other structures. Hurricane clips are basically sturdy metal plates with pre-drilled holes for screws or nails that are used to strongly bind wooden frames together. These cheap and simple additions to a home will substantially increase its resistance to the uplifting force of a tornado.
Responding the ever-present and only-increasing threat of tornadoes, in 2016 Dufferin County, Ontario implemented a hurricane-clip rebate program to help protect homes against tornadoes and other severe wind events. Southern Ontario is one of the most tornado-prone regions of the country and even the world. There have been multiple severe tornado outbreaks in the past several decades, with tornadoes occurring in Vaughan in 2009, Leamington in 2010, Goderich in 2011, Angus in 2014, and Dunrobin in 2018. Roofs are a common point of failure when a house is struck by a tornado, or even high winds, as they are subjected to strong upward lift forces that can damage or even outright remove a roof. The use of hurricane clips on roof rafters or trusses can substantially reduce the risk of this kind of damage.