Load codes get new look after roof collapses
As the Inland Northwest dug out from record snow, Steve Noll was more focused on what was on the ground, hampering travel and business, than what was above.
That changed Jan. 2, when part of his warehouse on Pittsburg Street collapsed under the weight of snow.
A potential collapse “didn’t even occur to me,” said Noll, who owns Interior Solutions, an office furniture business that remains open despite the roof problem at the company’s warehouse.
Although Spokane endured a record amount of snow in a month, most roofs should have been able to withstand the weight. But with dozens of collapse roofs across the Inland Northwest, some officials are wondering if the standards set in building codes should be re-examined.
For decades, code in Spokane and Spokane County has required roofs to be built so they can support at least 30 pounds of snow per square foot. The standard is at least 40 pounds per square foot in Coeur d’Alene and Kootenai County.
While localized areas reportedly exceeded the 30-pound mark – especially in northern Spokane County – the National Weather Service’s official reading topped out Jan. 6 at 28.6 pounds per square foot.
In many cases, building officials say, the roof failures likely were the result of deteriorated building conditions or possibly substandard construction rather than snow loads beyond the rated capacity.
Still, they say that drifting and localized weather patterns may have led to higher loads in some locations and that it’s often difficult to measure snow load after a collapse.
Noll said he’ll never know the weight that was on his building. A structural engineer blamed the collapse on an attached overhang, which failed and pulled out a wall when it did, causing the roof over about 35 percent of his warehouse to fall.
Spokane’s Building Department counted about 50 failures. Many were larger buildings, such as the Rosauers at Five Mile, but most were smaller structures, such as awnings, carports and small garages.
Spokane County and the city of Coeur d’Alene’s building officials said not including smaller structures, they each had about seven failures.
Spokane Building Director Joe Wizner said he’ll use the data and recommendations being gathered by the Structural Engineers Association of Washington’s Spokane chapter to help determine if rules should change.
Robert Graper, president of the chapter, said about 80 engineers and building officials discussed the collapses at a meeting this week.
“I can’t say that at this point in time I’ve seen any kind of a trend,” Graper said.
Most collapses were on buildings with flat or low-pitched roofs.
Spokane officials said there were only a couple of residential roof problems in the city serious enough for them to order people to stay out.
One dramatic collapse occurred at a home on East 11th Avenue. The house has been vacant for several years.
While collapses received a lot of attention, it’s important to keep the failures in perspective, Graper said.
“I think that the 30-pounds-a-square-foot (standard) is probably appropriate for this area based on the small number of buildings that came down versus the total number of building we have in the area,” he said.
It’s rare for snow weight to reach the limit. It happened in February 1969, when the weather service measured snow on the ground at 36 pounds per square foot in Spokane. In 1993, loads reached 27 pounds a square foot.
In Coeur d’Alene, roof load limits are set at 40 pounds a square foot. Ed Wagner, the city’s building services director, said measurements indicated that weights were near the limit when the thaw came.
“The way it all melted off, it was a blessing,” Wagner said.
Jonathan Brunt can be reached at firstname.lastname@example.org or (509) 459-5442.