The roof of an Alaska Railroad storage building at 801 W. First Ave. collapsed under a heavy snow load Wednesday night or early Thursday, and another commercial building in South Anchorage sustained a partial roof collapse Thursday evening.
No one was in the Alaska Railroad building, which is leased to a transport company and held plywood and lumber, said Tim Sullivan, the railroad's external affairs director. The collapse was discovered by a snow removal crew that arrived at 7 a.m. Thursday to clean the roof, he said.
Early Thursday evening, firefighters responded to reports of a roof collapse at Document Storage Inc, 2410 E. 88th Ave. A portion of that roof appeared to have sagged, but the building was mainly intact. Workers were beginning to clear snow off the roof at the time. No one was injured.
Last Friday, the auditorium roof at Abbott Loop Community Church caved in, forcing the church to move its services to Anchorage City Church for the near term.
With this winter's snow approaching a season record, there have been several large roof collapses over the past few weeks.
The city on Monday published a warning on its website that building owners and managers should "monitor the snow loads on their roofs.
"Of special concern are older buildings with flat roofs, and those with areas of snow drifting, such as at parapets and lower roofs. Special attention should also be paid to long overhangs where snow blankets are draping over the roof edge," the warning says.
City building safety officials are offering to talk to people with questions at 343-8211, then option No. 4.
The city hasn't heard of any house roof collapses, said Jim Stubbs, lead structural building inspector for the city. But that doesn't mean residents should ignore the danger, he said.
"The reason we've put out these advisories is people should be concerned."
City code calls for roofs to be designed to handle 40 pounds per square foot, and that standard has been in place for decades, said a city building official. That equals about two feet of dense snow.
"A roof designed to current code should not have problems until the load is significantly higher than 40 psf," the city advisory reports.
Stubbs said snow loads vary in different parts of town. For example, some neighborhoods around DeArmoun Road and in Muldoon have experienced heavier snowfall, he said.
The railroad building roof that collapsed this week gave way on the south side where snow had drifted to a depth of about three feet, Stubbs said.
It was built in the late 1950s or early 1960s, Sullivan said.
If it were built today, the construction would have been sturdier, Stubbs said.
Meantime, there hasn't been an official cause for the Abbott Loop Community Church roof collapse, said Frank Curry, a pastor there. The collapse occurred on the west end of the auditorium.
Workers have been shoring up remaining roof on the east end, then will demolish what's left on the west side, Curry said.
Reach Rosemary Shinohara at firstname.lastname@example.org or 257-4340.
By ROSEMARY SHINOHARA
Anchorage Daily News