Spring melt means the risk of roof avalanches increases

The snow slowly slips down a narrow-sloped roof.
The snow slowly slips down a narrow-sloped roof.(Alaska's News Source)
Published: Apr. 1, 2021 at 6:23 PM AKDT
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ANCHORAGE, Alaska (KTUU) - Dramatic video of snow sliding off a roof can give the viewer an idea of how much force and energy is released when a roof avalanche occurs.

Just such an avalanche happened at a home in Willow this week, and was captured by a home security camera.

Not one, but two roof avalanches

Wow! What a scary sight to see, not one, but two roof avalanches! When Shandra Lounsbury returned home in Willow Tuesday after running errands she found a new mound of snow next to the house. The security camera revealed where the snow came from, a roof avalanche dropping 4 to 6 feet of snow all at once right next to the house! Then today, it happened again on the other side. This time also causing damage to the house, knocking out power, and potentially causing a gas leak. Andrew Knowles says he's thankful his fiancee, Shandra, and their dogs weren't home during the potentially lethal snow slides. He was also away at the time, but now has not only snow to clear, but damage to repair. This serves as a reminder that roof avalanches can and do happen, and they can be deadly. At least three people have reportedly died in similar situations in just Alaska alone. Stay alert!

Posted by Melissa Frey on Wednesday, March 31, 2021

“You can get seriously injured from that,” said Chad Hansen, lead estimator with General Roofing in Anchorage.

This is mainly an issue for metal roofs, but it’s good to be cautious this time of year. On those warm days — or even cold days when the sun shines — heat melts the snow and a layer of water slips between the snowpack and the roof. This relaxes the grip of the snow on the roof and it releases, sending the avalanche off to the ground.

Hansen said if you’ve got a metal roof or are getting a metal roof, to be proactive, not reactive.

“Look where the snow is going to fall,” he said. “Get snow stops, be safe. The little money it costs for snow stops might save your car, your wife, your kid, your dog — you just don’t know.”

Snow stops are small metal bars about two inches tall that are placed on the roof to hold the snow in place.

Even roofs with shallow slopes can be the source of a roof avalanche.

“I call them creepers,” Hansen said. “It creeps and creeps and then one day, it just falls off. It doesn’t have to be a steep roof to be a dangerous roof.”

These kinds of avalanches are similar to glide avalanches in the mountains, where the whole snowpack slides as one piece. The lower portion of the snowpack starts to slip, cracks form near the top and, on a warm day, the water reduces the friction holding the snowpack in place and it gives way.

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