Over 1,000 Anchorage building owners warned of snow collapse risk and danger to workers

Jan. 31—Government officials in Anchorage have taken the unprecedented step of warning more than 1,000 commercial property owners that their roofs could be at risk of collapse because of this year's record-breaking snow loads.

In a letter, the city told building owners that if their roofs are determined to be at risk — or even if they aren't sure — "we recommend that no one occupy the space until the snow is removed from the roof."

The letters were sent late Tuesday from the Development Services Department to approximately 1,070 people with properties identified as possibly susceptible to roof failure.

[Read the letter from the Municipality of Anchorage Building Services Department]

"We're thinking we have hundreds of these buildings out there," said Anchorage acting building official Ross Noffsinger. "If they haven't removed the snow yet ... we're feeling that the potential for failure is high enough that we basically we need to make direct contact with the building owners and ... request that they remove the snow and not occupy the space until the snow is removed.

The letters include photos of the problematic roof structures, and photos of roof construction that are not a concern.

According to Noffsinger, last March, officials with the municipality identified the problematic design flaw common to most of the buildings that collapsed. The failures primarily occurred in structures supported by wooden truss beams connected with metal gang nail plates built before 1990, particularly among flat-roofed commercial buildings with long truss spans.

The letter is expected to start arriving in property owners' mailboxes before week's end.

Noffsinger said the municipality compiled a list of buildings at risk through a combination of property records and preexisting aerial surveys.

As far as he knows, the municipality has never taken such an extensive step to deal with the risk of roof collapse from too much snow.

So far this winter, at least five buildings have partially collapsed under the weight of heavy snow. More than 8 feet of snow has accumulated in the city this season, with more all but certain to arrive before the spring melt.

"The roof construction of concern has failed multiple times even when supporting less than 25 pounds per square foot of snow," the letter continues. "Additional time or snow could lead to failure."

The snowload on uncleared roofs has likely grown to about 30-35 pounds per square foot, after 17 inches fell on Anchorage early this week, he said. Anchorage code requires that buildings support a minimum of 40 pounds per square foot of snow.

Last February, one woman died in a collapse in a winter that saw at least 16 roofs fail. Nobody has been hurt or killed in this winter's collapses.

Building officials recommend that, in addition to clearing off snow, commercial property owners contact an engineer to assess the roof's condition.

Additional information is available at the city's building services website.

This is a developing story. Check back for updates.