Good Question: How Much Snow Can Our Roofs Handle?
By Jason DeRusha, WCCO-TV
MINNEAPOLIS (WCCO) — In the metro, the snow isn’t just piling up on the streets, it’s piling up on the roofs of our homes. After the Metrodome roof collapsed, many viewers wondered about the snow on their own homes.
“Curious to know (since we’ve had a LOT of snow),” e-mailed David Altfillisch, “Is my home roof safe with all the added snow sitting on it? Do I need to have the snow removed?”
“No, I wouldn’t be too worried about [the snow piled up on the roof],” said Jason Hanlon, who is the vice president of building services – structures for Ulteig Engineering in Fridley, Minn. Hanlon is a structural engineer.
“If you’re at about two feet or less, your structure will end up being OK,” Hanlon said. “Your roof really can handle two feet of snow … That’s what current code dictates.”
According to calculations prepared by WCCO-TV Meteorologist Mike Augustyniak, Saturday’s 17 inches of fluffy snow weighed about six pounds per square foot. Roofs in southern Minnesota have to be built to handle 35 pounds of snow per square foot on average.
The code for roofs changes depending on where you live. In northern Minnesota, roofs have to withstand 42.5 pounds of snow per square foot.
Roofs are built to handle even more than that, in case the snow drifts to one side.
“They’re two-by-fours that have these metal plates that connect everything together,” Hanlon explained. “That, as itself, is acting as a whole system.”
If you’re worried about your deck under the weight of the snow — don’t be.
“A residential deck, typically, should be designed for about 40 pounds per square foot,” Hanlon explained. That’s five more pounds more per square foot than the average roof structure.
Decks are built to support the weight of a person about every two square feet.
“If anyone has any question on the adequacy of their roof, they should contact a registered professional engineer to come out and evaluate their condition,” said Hanlon.
WCCO-TV’s Jason DeRusha Reports