The weight of snow on the roofs of homes and businesses is something property owners need to be concerned about this winter, according to Tom Blackmore, building inspector for the city of Jamestown.
"New snow, old snow and potentially ice buildup," he said. "It all adds up to more weight than anticipated. We've seen some structural failures."
The most recent storm brought 16 inches of snow with more than 2 feet of new snow falling in Jamestown since Christmas.
In Fargo, there were reports of decks attached to apartment buildings failing, Blackmore said.
In Jamestown, the roof of an already condemned building on Business Loop West collapsed sometime Thursday night or Friday morning. There was no one injured in the incident.
The building in Jamestown had sustained structural damage last winter when an awning collapsed. Occupancy of that portion of the building was prohibited since then.
Next to the building is The Salvation Army Thrift Store, an attached separate building that is considered structurally sound although Blackmore said he ordered it evacuated Friday morning while the snow was removed from its roof.
Blackmore said there is no simple test to determine when there is too much snow on a roof.
"Each roof is different and it differs around town," he said. "It varies so much it needs to be evaluated on a case-by-case basis."
Some of the factors include how steep the roof is and how sheltered the area is by trees that would prevent the wind from blowing the snow off the roof.
Modern homes designed for the northern United States should tolerate a snow load of 40 pounds per square foot although older homes may have weaker roofs. If in doubt, the property owner should call a contractor to inspect the roof and determine if the snow should be removed, Blackmore said.
"If the snow needs to be removed, do it safely," Blackmore said. "If you can do it from the ground, that is safer. Leave a little snow on the roof so as not to damage the shingles."
While the property owner inspects the roof, he or she should also be sure than things like gas meters, any vents from the building and area fire hydrants are free of snow, Blackmore said.
"It is the property owner's responsibility to the neighborhood to make sure the Fire Department can access the fire hydrant as quickly as possible," he said.