Municipal inspectors advise owners of some older commercial buildings to clear snow from roofs

[Above: An indoor camera aimed at the front door of the FashionPact store near downtown Anchorage captured the March 4 roof collapse. A traffic camera captured the collapse from a distance. Videos courtesy James Clancey]

After the roofs of three commercial buildings crashed down in Anchorage in the past three weeks, municipal building inspectors on Tuesday issued a warning asking owners of certain buildings to clear their roofs of snow and ice “as soon as possible.” The region has seen a series of heavy snowfalls this winter, and snow and ice are piled high on rooftops across the city.

The collapses occurred in buildings constructed between the mid-1970s and mid-1980s, with wooden trusses supporting the roof, Ross Noffsinger, acting building official for the municipality, said in a statement.

In some cases, the metal plates from that construction era may have been too small or not properly placed, potentially allowing beams to split and trusses to break, according to the municipality. Rooftop snow or ice can compound the problem, adding pressure from above, Noffsinger said.

Large portions of roofs buckled at a transmission shop off Dowling Road on Sunday, a thrift store near downtown on Saturday, and the Turnagain CrossFit gym in South Anchorage over two weeks ago, where one person was killed and two others trapped.

“The trusses are breaking,” Noffsinger said in an interview. “We don’t know how they’re breaking, but they’re breaking.”

Both the thrift store, built in 1983, and the CrossFit gym, built in 1979, had the same truss design, according to the city. The auditorium of the Abbott Loop Community Church, which collapsed dramatically in 2012, also used that truss design, according to private engineers familiar with the building, Noffsinger said.

Meanwhile, the Anchorage School District closed libraries at five elementary schools this week, amid concerns about heavy snow loads on roofs. But on Tuesday, the district confirmed those buildings are not made with truss designs the city is concerned about.

In the three commercial buildings that collapsed, Noffsinger said the chain of events that caused the trusses to crumble isn’t known, in part because some evidence is destroyed in the collapse.

“It’s really hard to go back and forensically decide what is the exact mechanism that caused these to fail,” Noffsinger said.

Noffsinger said the city plans to have the trusses in each collapse analyzed, potentially working with a contractor and using design software to analyze strengths and potential failure points.

Tuesday’s statement was an update to a warning the municipality issued last week that identified potential problems with so-called top-chord hung trusses from the 1970s and 1980s that can be found in flat-roofed commercial buildings.

The top-chord hung trusses were found in the FashionPact thrift store and the Turnagain CrossFit gym, according to the city. Noffsinger said engineers also found top-chord hung trusses at the Abbott Loop Community Church, the location of the 2012 collapse.

The city’s warning asked building owners to look for cracking in the top beam, in particular. They should also look for metal plates that don’t extend to the top of the upper beam, and therefore might not reinforce it well. Such trusses will need to be analyzed by a structural engineer and potentially reinforced, the city’s statement said.

Any cracking in the top beam demands immediate attention, and if there is snow or ice on the roof, people should evacuate portions of the building where the roof might collapse, the municipality said. The municipality said it should also be informed if there is a problem, and people can call the Development Services department at 907-343-8301.

On Tuesday, the city said that the potentially problematic top-chord-hung trusses were not found in the Quality Transmission Service building off Dowling Road, built in 1974.

That building has a peaked roof, not a flat one.

But commercial building owners should also be inspecting wooden trusses if they were built in the mid-1970s to mid-’80s, Noffsinger said.

“If you own a building falling within these parameters, we ask that you remove the snow/ice from the roof as soon as possible,” the statement said, referring to commercial buildings with flat and pitched wooden trusses from the mid-‘70s and ‘80s.

“We ask that snow removal contractors prioritize these types of buildings,” the statement said.

The building that collapsed on Sunday has a roof pitch common in many houses across Anchorage, Noffsinger said.

“It could also be a problem in houses, we just haven’t seen this problem in houses,” he said.

The concern right now is with commercial buildings, he said.

Engineers have said this year’s heavy snow is not too much weight for the vast majority of Anchorage houses.

Thick ice buildup, called ice damming, has been identified as a potential problem at the flat-roofed CrossFit gym, because it appeared to be well beyond the city code design standard of 40 pounds per square foot.

But the snow and ice load at the two Anchorage buildings that collapsed over the weekend appeared to be less than that design standard, Noffsinger said.

The snow was cleared earlier in the winter at the FashionPact building, building owner James Clancey said in an interview Monday.

The building had about 8 inches of snow and not much ice buildup to speak of, he said.

“It definitely does not seem snow- or ice-related,” he said of the collapse. It’s hard to say what the problem was, he said. Engineers have speculated that maybe there was unseen water damage, but the municipality might learn from analyzing the building’s trusses, he said.

The roof at Quality Transmission off Dowling had some ice damming. But that was located near the eaves, close to support from walls and likely not a factor in the collapse, Noffsinger said.

The owner of that building, Greene Nickell, stood outside his transmission shop on Monday looking at the collapsed roof and waiting for a private engineer to arrive. The engineer was expected to provide information about when the uncollapsed portion of the building can be safely reentered to retrieve belongings.

Nickell said the collapse blew out a bay door and crushed a 1975 Ford Highboy truck he’d restored as a personal project.

“I’m just thankful no one got hurt,” he said.

No Anchorage school buildings are designed in the manner that the city has warned about, according to the district.

Cracks in the library ceilings of Klatt and Spring Hill Elementary prompted the district to announce it was closing libraries at those and other similarly designed schools Monday, including Fire Lake, Bear Valley and Ravenwood elementary schools.

Steel girders, or structural steel beams, over the libraries had flexed somewhat, pushing down slightly on steel two-by-fours, said Rob Holland, the district’s senior director of maintenance and operations.

”Schools and hospitals are the safest buildings you’d ever want to find yourself in, they just are — bar none,” said Holland. “They’re engineered, typically, to a higher standard and to higher seismic codes.”

Daily News reporter Morgan Krakow contributed.