The main reason you should keep your roof as snow free as possible is that it’s crucial for preventing ice dams from forming on your roof. If you’re able to prevent ice dams you are less likely to have damage to your roof or home.
As a rule of thumb one square foot of snow that is one inch in depth weighs about a pound. If your roof has 12 inches of snow on it, that could easily amount to thousands of pounds of stress on your roof, not to mention the weight the ice amounts to from the ice dams. Minimizing the stress placed on your roof is a great way to minimize the risk of leaking and cave-ins, which happen more often than many people may think.