Last Thursday, Chad Hansen used a big forklift to deliver three snow blowers to a flat roof in a Midtown Anchorage office park, where there was about 3 feet of snow, literally tons.
“Aw, this is just fun, itin it? Did that one last night,” he said, gesturing to the next building over, “now this one today.”
Hansen owns General Roofing Co. Businesses like his have been slammed with snow removal work this winter. Even paying $30 an hour, Hanson’s crew today is down a few guys. They’ve been getting worn out, he said.
“There’s a lot of it to go around right now, you know?” Hanson said.
Across Tudor Road, a different crew was clearing snow off the top of another office building.
Anchorage has gotten more than 100 inches of snow this season, setting various records in November, December and January. A fresh series of roof collapses from the heavy snow load this winter – at least 10 so far that the fire department’s responded to – has prompted city building officials to take a more active role in identifying and managing the risk.
Daniel King is an engineer in the city’s development services division. He’s been working on the city’s roof guidance, which is not his typical work. He said the level of building failures last winter and this winter have been exceptional.
“And so it’s an evolving situation where we’re trying to move as quickly as the situation is growing, as the danger grows,” King said.
According to the division’s latest snow removal notice, residential buildings built after 1990 should generally be able to hold up to heavy loads. But signs of distress like a sagging roof, doors and windows that have begun to stick or jam, and strange creaking, popping or cracking coming from the roof or attic are all signs that it’s time to clear the snow off your roof.
The roofs that have been failing have all been on commercial buildings, according to the Anchorage Fire Department. The city is particularly concerned about roof supports called “parallel chord metal plate-connected wood trusses.” Six of the failed roofs this winter had these trusses, King said. The city’s notice says some failed with a significantly lighter load than they’re designed to withstand.
The city doesn’t know exactly which buildings have these trusses.
However, King’s division used public property data and some knowledge about how building codes changed to make educated guesses about properties that might be built like the ones that have failed. Starting with roughly 90,000 parcels city-wide, King said they filtered for commercial properties built before 1995 made of wood or fire-resistive materials, rather than steel or fireproof materials. Large condo buildings with more structural redundancies were also filtered out.
They identified about 1,200 older commercial properties across the city that fit those criteria.
“That does not mean that 1,200 have this type of truss, because it could be a different type of construction that is wood. It could be something else,” King said. “And so we are asking people to respond and let us know, do you have this type of truss? Or, do you have a different type of construction that hasn’t seen the same pattern of failure?”
In the past few weeks, his division sent the owners of these properties warning letters with this information, how to identify their trusses, plus advice on inspections and snow removal.
“We’re mostly concerned with the warehouses and larger, longer spans of buildings,” King said.
The city recently mailed out another 6,000 notices to tenants of previously notified property owners. They published an interactive map on Thursday with a little bit of information about roofs that have failed, properties that might have the trusses of concern, and properties they’ve confirmed do have them.
The map, which is being updated daily, shows 19 roof failures since last winter, which was also unusually snowy. The city is asking snow removal contractors to prioritize the higher risk buildings.
The General Roofing crew was on one of those potentially riskier buildings. With the snowblowers running, they were making short work of the snow load – until they realized there were little vents protruding up, buried in the snow.
“All right, shut it off!” Hanson yelled to his crew. They switched back to shovels to dig out the vents.
Anchorage had more than 100 inches of snow in the winter of 2011-2012, too. That February, the Anchorage Daily News reported on the “unusual” collapse of two commercial buildings’ roofs within a week.
Editor’s note: Daniel King is married to an Alaska Public Media staff member.
Jeremy Hsieh covers Anchorage with an emphasis on housing, homelessness, infrastructure and development. Reach him atjhsieh@alaskapublic.orgor 907-550-8428. Read more about Jeremyhere.
