A preliminary report report released by the Institute for Catastrophic Loss Reduction looked at how the 1,500,000-acre Fort McMurray Fire ignited some of the 2,400 structures in the Alberta city in May of this year.
Below are excerpts from the document.
After evaluating the fire environment and clearances between homes and the forest edge, the investigator discounted direct contact from flames or radiant heat of the forest fire as being significant sources of home ignition at Fort McMurray. Instead, it was concluded that wind-driven embers were the most probable cause for the majority of early home ignitions in the zone where the fire made its transition from forest into urban neighbourhoods. Once established, the fire would have spread from structure to structure as an urban conflagration, accounting for the majority of home losses.
In all neighbourhoods studied, homes whose owners had adopted FireSmart guidelines survived much more frequently than homes where they had not, despite the extraordinarily harsh conditions.
Recommended FireSmart guidelines work. They are effective in reducing the probability of home ignition and wildfire losses. Home survival does not appear to be random or a matter of luck.
Home survival depends on conditions in the home ignition zone, for which owners are responsible.
While low total hazard rating is important, a single critical weakness can lead to home loss.