Snow Exceeds Regulations County Standards For Roof Support May Be Too Low For Usual Amount Of Snow Here
Sandpoint beer distributor Bill Jones is drafting plans to replace his old warehouse, which collapsed last week under heavy ice and snow.
But his new shop won’t meet Bonner County building codes.
It will exceed them.
Jones said he and others have learned the hard way that code requirements for roof strength are too lax to handle extreme winter weather.
In recent weeks, moisture buildup has caused roofs to collapse at two public schools and dozens of businesses, garages and barns in Kootenai and Bonner counties.
In most cases, the buildings weren’t poorly constructed. The collapses typically involved structures that met county safety regulations.
The problem, several building experts said, is that regulations themselves are inadequate.
It was merely luck that no one was hurt during the collapses, experts said. And if regulations had been adopted as recommended 15 years ago, taxpayers might have been spared a $200,000 repair bill at two Bonner County schools.
“The code requirements are not enough. That’s obvious,” said Rick Ulveling, a state building inspector responsible for all five northern counties. “I definitely think it’s time they’re changed.”
At issue is a rule used region-wide that requires most building roofs to be sturdy enough to handle up to 40 pounds per square foot of snow and ice.
In the wake of recent storms, Ulveling and the man who heads Bonner County’s building department plan to recommend boosting that capacity to 50, 60 or 70 pounds for some new buildings.
Some area engineers support the move, but the pair likely face an uphill political battle from builders and other inspectors.
Those opponents say the price of repairs or risk of injury isn’t great enough to justify the cost of new rules - even while they admit the cost would be minimal.
Requiring building tops to withstand the worst Idaho storms would increase most construction costs by less than 1 percent - under $1,000 for a $100,000 home. The difference generally is as simple as using thicker, stronger wood or metal roof supports.
“If you view it from the point of a home buyer, it sounds like good insurance,” said engineer Jim Meckel, who supports the changes. “If you view it from a builder putting up 20 houses in a season, then it starts to add up to real money.”
Meckel describes the problem as one of risk management. But accurately assessing the risk is difficult, if not impossible.
Cities and counties nationwide establish roof snow load requirements based on projected snowfall. North Idaho’s 40-pound requirement is based on a 15-year-old study of weather patterns by University of Idaho engineers.
But some question the study’s accuracy. Others say it’s not even being followed.
The study suggests only one Coeur d’Alene winter in 50 is likely to produce moisture that could accumulate 40 pounds or more on a roof.
That one in 50 winters clearly came this year.
The National Weather Service reported more snow in December - 43 inches in Spokane - than in any other one-month period going back 100-plus years. That directly followed a severe storm that left up to 3 inches of ice on many rooftops.
Still, many weather watchers believe snow accumulation was nearly as severe in the winter of 1992-1993. And 1985-1986. And 1973-1974. There’s no telling when a similar winter could come again.
“By my calculation, we’ve had snow loading in excess of 40 pounds at least 3 or 4 of the last 19 years,” Meckel said. “That suggests to me that the standard is too low.”
Meanwhile, the university study shows snowfall increases to the north and suggests roof thresholds should rise accordingly. In Sandpoint, for example, the study recommends roof capacity be 75 pounds per square foot.
But “Bonner County has been using 40 pounds because it was politically decided years ago that it would be that way,” Garrison said.
That means roofs on buildings such as Jones’ 16,000-square-foot beer warehouse, or the Sandpoint High School auditorium, quickly reached their capacity for snow. Drifting snow caused both roofs to fail.
“In one night, we had 8-foot drifts on the part that ended up caving in,” Jones said. “We just never anticipated it.”
The county lost more than 30 buildings in December. Most were storage facilities, but at least seven were businesses.
Garrison plans to recommend that county commissioners increase roof capacity on new businesses or public buildings to 75 pounds.
The situation is only slightly less dramatic in Kootenai County.
In downtown Coeur d’Alene, a 70-year-old theater, a vacant children’s gymnastics club and a clothing store collapsed. Across the county, outbuildings caved.
“In most of the ones I’ve seen, the structure was designed for 40 pounds, was adequately designed and adequately built,” Meckel said.
Even county building chief Dave Daniel says parts of Kootenai County consistently get snow built up at more than 40 pounds per foot.
But - after consulting with the North Idaho Building Contractors Association - Daniel maintains there’s no evidence that snow load standards need to be increased.
“When you take a look at the total number of collapses, it’s pretty insignificant,” Daniel said. “As far as my knowledge, we haven’t had any single-family home roofs collapse.”
Garrison in Bonner County said homes are less vulnerable because the materials include a greater “fudge factor” than those used for commercial buildings.
Besides, Daniel said, concerned residents can shovel snow from their own roofs. And some contractors already build to a higher standard on their own, he said. But he said stiff competition meant most stuck to minimum requirements.
Daniel said he primarily fears a “knee-jerk” reaction that would make building more expensive. He prefers to wait until the problem is more acute.
“If we started seeing single family homes and trusses failing more than we currently have, most certainly we would have to take a look,” he said. “If the decision is made to increase it, then the cost of doing that has to be taken into consideration.”
But Ulveling, the state inspector, and Meckel said after a winter like this one, it may be too risky not to increase snow loads.
“It’s a philosophical question,” Meckel said. “On a pole building, the cost of a roof failure may be less than the cost of building a stronger unit. But when you get into residential or commercial, suddenly you’re talking about more than money; you’re talking about buildings that are used by people. You’re talking about health and safety,” he said.
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