In Anchorage, snow is piled high on many rooftops and homeowners are wondering if they should shovel it.
Acting Anchorage Building Official Ross Noffsinger said the snow load in the city is about 60% to 80% of the designed maximum for residential roofs.
“We really wouldn’t be recommending getting up and shoveling a roof right now, given the potential to fall off the roof,” he said.
Still, some homeowners might want to consider it, said longtime home inspector Dave Mortensen from Discovery Home Inspection.
“The snow storms have produced so much snow at once that roofs that had never performed poorly before are performing poorly now,” Mortensen said.
Mortensen said owners of old houses could have cause for concern about the weight on their roofs. That goes for homes built before building code enforcement began in the 1970s or with recent changes to insulation or attic ventilation, which can cause a roof to hold more snow than it used to.
For homes built in the 1980s or later, the issue isn’t so much the weight as the ice accumulating on the eaves. Atmospheric conditions have been ideal for ice dams, Mortensen said.
Ice dams occur when the bottom layer of snow on a roof melts. Water runs under the snowpack until it reaches the edge, where it freezes. Ice dams have been building this winter, blocking more snowmelt from draining and forcing it up under shingles.
Homeowners across Anchorage report leaking in their homes.
Mortensen said removing snow above an ice dam is a good idea, to halt the growth.
“If you can stop that pattern by removing that fuel, basically then the ice dam will stop in that area,” he said.
Throwing granulated ice melt on the ice can help, Mortensen said, to give a path for the water to run down. He cautions against using metal tools, or scraping down to the shingles, to avoid damage to roofing material.
If homeowners want to remove snow because of problematic ice dams, the Anchorage Office of Emergency Management warns to beware of where the snow and ice will land. The office recommends doing the work with a partner or consulting with a licensed and bonded professional.