This is how the roof looked when Anne-Mette and family came to the cabin on Utvikfjellet mountain in Western Norway in late December. (Photo: Anne-Mette Hjelle)
Extreme low pressures from the west have resulted in heavy snowfall in the mountains of Western and Eastern Norway – and in many places, the snow depth is between 2 and 4 meters. House and cabin owners are concerned: How much snow can the roof withstand before it collapses?
– It is better to shovel than to wonder about the weight of the snow, says senior scientist Trond Bøhlerengen at the Foundation for Scientific and Industrial Research (SINTEF) to the weather service yr.no.
Many have already been shoveling a lot this winter. Others have calculated that the roof withstands even more snow and is postponing the job.
If we are to believe the senior scientist, it is better to get outside and shovel than to sit indoors worrying about when the roof is going to collapse.
One meter of wet and hard-packed snow is obviously heavier than a meter of dry and loose snow – but finding the exact weight is difficult.
– You have to know a lot about the history of the snow to find the weight. I recommend everyone just to start with the snow depth, says the senior scientist.
The Expert’s Advice
– If you look at the snow depth, there are two rules that apply in Norway, says Bøhlerengen:
Cabins built before 1980: The roofs are usually dimensioned for a critical snow load of 150 kg/m², and should be shoveled when the depth exceeds 0.5 meter.
Cabins built after 1980: The roofs varies in how they are dimensioned and one should shovel when the snow depth is approaching 1 meter.
Shovel while the snow is dry and light, Bøhlerengen continues. Wet, old snow can quickly become a burden on the back and heart.
– There are probably more people who have died from shoveling than snow sliding off the roof hitting somebody.
However, there is a misconception that the total weight goes up when the temperature rises, and the snow gets wetter.
– You have a given amount of snow on the roof whether it is mild or not. Everything is water in solid form, says Bøhlerengen and adds:
– Remember that if the weather changes and it gets milder with additional rainfall, roofs may quickly get a severe overload.
Text modified by: Thor Lanesskog, ThorNews