Assessment of damage to residential construction from the tornadoes in Vaughan, Ontario, On 20 august 2009

The results of a detailed damage investigation of the two tornadoes in Vaughan, Ontario, which were part of the 19 tornadoes in the outbreak of 20 August 2009, are presented. The bulk of the damage in both tornadoes consisted of structural roof failures categorized as EF-1 on the Enhanced Fujita Scale. However, multiple houses in both tornadoes suffered total roof failure, which is EF-2. It was observed that the total roof failures were all due to either internal pressurization and (or) weak (or non-existent) roof-to-wall connections. Wind speeds for specific damage states are estimated using median values from published fragility analyses and compared to the wind speeds found in the EF-Scale. The current results indicate that applying fragility concepts to the EF-Scale may allow for future improvements and verification of the wind speed – damage relationship for tornadoes.