Firehouse.com recently reported the loss of two firefighters in Yellowknife, Canada. Without specific reference to the Yellowknife fire, I offer some thoughts on operating on roofs loaded with snow and ice.
In 1927 on the coldest day of the year, FDNY lost four firefighters in a warehouse fire collapse. The operation had been defensive with multiple heavy streams including fireboats. The operation was winding down and two engine companies were sent into the building. Without warning the building collapsed. The cause was ice build up and the weight of water soaked textiles. The warning was there but was not recognized.
Some years later, Chicago firefighters were battling a blaze in a commercial building. There was a thick layer of ice on the roof. Firefighters cut through the ice to cut a vent hole. As they moved to cut another hole, the roof collapsed and three firefighters died.
Fire training manuals show sketches of vent holes emitting smoke but I have never seen a reference to the fact that the vent provides an air flow to the fire which is probably not confined to the contents but is also attacking the structure.
If the roof itself is burning. It is being weakened. The structure is already overloaded by the heavy ice, and additionally overloaded by the dynamic load of the firefighters. As usual the collapse occurs without warning. The warning was there in the form of thick ice, or heavy snow. It is foolhardy to determine the breaking point of a structure by putting firefighters on it.
The point of venting is to allow firefighters to operate within the structure. Firefighters should not be in a building where collapse is a serious potential. No one is smart enough to know when a structure under attack by fire, will fail.
As usual I quote Vincent Dunn "No Building is worth a firefighter's life". The force of gravity wants the firefighter on the ground. The GRS (gravity resistance system) is being attacked by fire. Who knows when gravity will win? We train firefighters in buildings designed not to collapse All such training should include discussion of collapse and hidden fire hazards rather than leaving it to be learned by DEADLY EXPERIENCE.
The title of my columns is "The building is Your Enemy" Believe it and act accordingly. Be aware that firefighters who run mostly medical calls may overreact to a real fire.