Large amounts of snow in southern Norway are causing many rooftops to be in danger of buckling under the weight and collapsing. And more snow is reported to be on the way.
Now, the Advisory Engineers’ Association (RIF) have given a warning to those who have not yet cleared their roofs. The next few weeks could be critical for roofs that have accumulated wet and heavy snow during several rainy periods during the winter.
“Insurance companies receive hundreds of cases of damage due to heavy snow every winter. If the roof breaks under continuous, heavy snowfall, the insurance covers everything. But if the snow accumulates throughout the winter, and the homeowner doesn’t remove it, they risk a reduction of the insurance, or a higher deductible,” said Øystein Løset, an expert in building constructions at the RIF.
Wet snow most dangerous
It is not necessarily the height of the snow on your roof that is the benchmark for when you should pick up a shovel or snow box, but what kind of snow it is. On average, 1 meter of snow weighs approximately 300 kilos per cubic meter. But wet snow is heavier.
“The rule of thumb is that one should look at the roof when the snow depth approaches half a metre, especially on older houses and cabins, but estimate the snow weight to be on the safe side,” said Løset.
The age of the houses makes a difference. Houses built before 1980 have roofs that can withstand up to 150 kilos of snow weight per square meter, while the limits for houses built after 1980 are between 250 and 350 kilos.
With wet snow, this corresponds to about half a metre of snow for houses built before 1980, and up to 90 centimetres of wet snow for houses built after 1980.
When you first remove snow it is also important that you do it properly. “It’s especially important to take equal weight from each side. If you only take half from the front, and leave the back, the load gets uneven and you’re making it worse”, warned Løset.
The JHA wants a scheme so that the municipalities can alert inhabitants when it is time to remove snow from the roof.
“We wish the municipalities to take responsibility for spreading information about the dangers of snow weight, and the need for the local media to give warnings in the same way as they do for avalanches or floods. If not, we fear for life and health after a long snow-bound winter as it has been this year”,said the CEO of RIF, Liv Kari Skudal Hansteen.
© NTB Scanpix / #Norway Today