So you are probably trying to avoid this...
Well in Switzerland they are using Schneestops to make sure it doesn't happen to them!
We wondered how our neighbors across the pond deal with roofborne snow and ice hazards, and Switzerland-based reader Christian put us on to Schneestops. Having been used in the Alpines for over 30 years, Schneestops ("snow stops"
are a simple, clever, and retroactively-installable solution to prevent large chunks of ice or snow sliding off of your roof and harming whatever's beneath them. (Check out the wrecked Honda in our last entry on the subject.)
The idea behind Schneestops is pretty brilliant: Assuming your roof is built strongly enough to handle the weight of snow, as they are in the Alpines, and assuming your roof is watertight, as it should be, then it's better to actually hold the snow in place on top of your roof, like this:
Snow serves as an excellent insulator, so you might as well get a little extra R value from Mother Nature's wintry gift.
To that end, Schneestops are metal brackets with a right angle placed in the bottom end:
Learn more
here!