The time for snowfall is not over yet. For homeowners, this means: be careful and look at the roof, because it’s the crowd that counts. 10 centimeters of powder snow weigh about 10 kilos per square meter. In the worst case, there could be a collapse.
As light and airy as it floats down from the sky, snow has real weight in the fallen mass. TÜV Rheinland points this out. If powder snow weighs even less, wet snow can put undue stress on a roof construction.
A comparison: 10 centimeters of powder snow weigh about 10 kilos per square meter, wet snow four times as much. If the snow freezes to ice, it is even 90 kilos. So it is tricky when a lot of snow has fallen and it freezes and thaws alternately.
This can be particularly critical on larger flat roofs or slightly sloping roofs where snow collects. Superstructures such as skylights also cause drifts, which can increase the load in some places.
In the worst case, there could be a collapse. Timely clearing is therefore best announced while there is still powder snow on the roof. According to Wolfram Stahl from TÜV Rheinland, however, it is difficult to say from what quantity clearing is necessary. “It depends on the respective statics.”
Stahl warns that homeowners who want to remove snow from their roofs themselves must be extremely careful. It makes sense to put on a safety belt and remove the snow from different sides to avoid one-sided loads.
Caution is also advised with possible skylights or solar panels on the roof. Homeowners usually know where something is. If a company is commissioned to clear snow, it is advisable to mark such places. “You could attach a small staff or a flag there,” says Wolfram Stahl. A professional can do that too.
Incidentally, sloping roofs should not carry too much snow, otherwise these masses could slide down as a roof avalanche and cause damage there.
