City of Spokane Building Official Joe Wizner is advising owners and tenants of buildings with flat or very low sloped roofs to take steps now to remove snow and reduce the risk of collapse.
With an additional 6 inches of snow last night, many buildings which had sustained the weight of recent snow storms finally succumbed last night. An additional four buildings suffered from collapsed roofs this morning bringing this week’s roof collapse total in the City of Spokane to about 28, which include a mix of commercial buildings, industrial buildings, awnings, carports, and residential garages.
“The low-slope roofs like warehouses and commercial buildings (strip malls) are probably the most susceptible to failure,” Wizner said. “With more snow in the forecast, the loads will get heavier and threaten more buildings.”
The roof drains on flat or low-slope roof building are easily blocked by ice, so even when we get a day of thawing in between snowy days, the weight on the roof won’t diminish since the snowmelt likely isn’t draining. The additional weight of people shoveling and equipment like snow blowers also can contribute to the collapse potential so taking steps now before new snow adds to the load is critical, Wizner says.
Car ports, trailer homes with flat roofs, and similar structures also could be at risk.
Single-family residential structures in the region are holding up much better than the low slope roofs. While there is a lot of ice damning occurring, the City is not getting reports of residential roof failures other than carports, awnings and accessory structures.
The City Building Official is encouraging property owners and tenants to use extreme caution when clearing the roofs of these buildings themselves. If you are hiring help to remove snow, always use licensed and bonded professionals like roofing contractors.
If you believe your building already has sustained damage and the roof may collapse, you should have a structural engineer evaluate the building for evidence of over-stressing, such as doors sticking, sheetrock buckling, or signs of bowed walls or ceilings. Any creaking or snapping sounds should be considered a serious warning to vacate the building until it is evaluated.
Spokane Fire Department officials also advise that commercial property owners be mindful of snow depth that may obstruct boiler vents on roofs which could cause a build-up of carbon monoxide inside the building. Many older vents may rise only two to three feet above the roofline.
Please report collapsed or partially collapsed buildings to the City of Spokane Building Department at 625-6300. The Building Services Inspectors can post buildings that have been damaged as “Unsafe to Occupy”.
An engineer is needed to evaluate the structures before they can be deemed as safe to occupy.
