With the heavy snowpack this winter, home and business owners are advised to know the warning signs of potential damage to roofs.
According to FEMA, one foot of fresh snow can range from three to 21 pounds per square foot depending on the moisture content.
Structural engineer Phil Bachofner, PE of Stahly Engineering & Associates, said the ground snow loads in Helena are currently around one pound per inch in depth.
“Basically, the current snow we have on a modern roof is good for 30 inches of snow,” Bachofner said.
He noted the ground snow load does not necessarily reflect the snow load on any given roof. Features like the roof’s slope will factor into the actual snow load.
Montana code requires all new buildings to be designed to support a minimum snow load of 30 pounds per square foot.
Aubrey Yerger, PE, a structural engineer for Morrison-Maierle, said a roof collapse is uncommon, but people should be concerned if they see sagging in the roof, new cracking in the interior, or new water leaks.
“You should also look for excessive drifts in roof valleys and unbalanced snow loads,” explained Yerger. “Ice damming can also be problematic especially when we get into those warmer temperatures. When ice forms at the edge of your roof it can prevent snow from sliding off when it does warm up.”
Bachofner said the majority of building damage he tends to see is related to water of some kind.
“If you can heat the gutter it will help,” said Bachofner, “and heat tape is always a good option.”
Yerger also recommends people concerned about the amount of snow on their roof contact a contractor to remove it. That way no inadvertent damage is caused to the property.
Both engineers said if a person sees sagging in their roof or cracks significantly widening, the building should be evacuated and a structural engineer or building inspector should be consulted.
-Reported by John Riley/MTN News