HELENA – Home and business owners are being advised to know the warning signs of potential damage to roofs as a result of our heavy snowpack.
According to FEMA, one foot deep 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.
Bachofner 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 to contact a contractor to remove it. That way no inadvertent damage is caused to the property.
Both engineers say 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.
