The condensed answer is roof leaks aggressively in the process of happening, and beavers have nothing to do with it. Next comes the what, how, where, and why.
It begins with the interaction between warm and freezing cold air. Heat always seeks cold. In the summertime, understanding that principle helps you realize it’s the heat coming in rather than the cool getting out. In the wintertime, most people think the cold air is getting in when it is really the heat going out.
Your attic and roof is the battleground for this heat transfer. Warm air from your home seeking the cold begins melting snow on your roof in the process. The water, being faithfully obedient to gravity, runs down to cooler edges and eaves where it freezes in ever increasing layers forming an ice dam.
The ice dam forms a pond of water freezing into more ice getting deeper until it begins to back up under the shingles. Then the real damage begins as it both degrades the shingle material and causes leaks. You don’t need to be a roofing expert to know that leaks cause structural damage along with the unsightly water stains inside your home.
It wouldn’t be fair to just leave you hanging at this point. There are solutions to control ice damming and prevent roofing damage. We will cover that in the next post about ice and water shields and how they will give you peace of mind when Michigan winters dish out cold and snow. Then you can laugh like children sledding instead of worrying about your roof.