Saving your roof from snow build up

Weather Wednesday

Roof collapse
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FARGO - It's hard to forget the moment the Metrodome roof collapsed right before a Vikings game twelve years ago. In the two days leading up to the metrodome roof collapse, the Twin Cities picked up more than 17” of wet snow.

Since the water content in the snow so was high the fiberglass fabric roof, supported by air pressure, wasn’t enough to keep the snow at bay and the baggie buckled under the heavier snow. It was the fifth and final time a tear or collapse caused chaos for the Metrodome, though the other four were all in the 80s.

But this isn’t just a freak occurrence for football stadiums: buildings with flat roofs are more susceptible when the snow stacks up. Anthony Stock, Assistant Manager MAC’S Hardware in Fargo says sloped roofs don’t collapse as easily, “Anything with that flat roof with snow is just going to sit and accumulate and potentially drift on your roof.”

It’s a disaster that has been going on for ages, this is Fargo North’s High School gym from 1966, Trail King Industries suffered a snow collapse just three years ago. But it is not just domes and flat roofs that are at risk, even roofs with more of a slope can collapse if there is enough snow or even just the right type of snow.

Fluffy snow may pile up quickly but it doesn’t weigh as much, roughly four pounds per square foot since there isn’t much water in it. Moderate snow with a bit more moisture weighs about six pounds per square foot but when the temperature is warmer, it’s wet snow that falls and that weighs the most: twelve pounds or more per square foot. Twelve inches of that type of wet snow would weigh about the same as three pick-up trucks on the roof. Most roofs on homes can withstand about 20 pounds per square foot.


We do see a lot more light, fluffy snow around here but snow density does increase over time, just as we can expect the snow to increase throughout the winter so we shouldn’t be complacent. “There's a few different things you can do: one we have our snow rakes just rake off the snow. It's as simple as it sounds. It's a long extendable pole. Put it up on your roof. Uses as the instructions kind of describe. Whenever we get those heavy snow falls two feet it’s smart so it doesn't compact once it starts melting. We also have a roof melt. Simple as throwing a hockey puck onto the roof,” explains Stock.

Jesse Ritka is a StormTracker meteorologist and holds the AMS Certified Broadcast Meteorologist seal of approval.

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