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.

Ice dams can’t form without snow.  If you’re able to prevent ice dams, you’re far more likely to prevent your roof from leaking and damaging the inside of your home.

Another reason roof snow removal is so important is that it’s a good idea to keep all that excess weight off your roof.  As a rule of thumb, one square-foot of snow that’s 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.  That’s not even counting the weight of any ice dams that may form as a result of leaving the snow on your roof; just one cubic foot of ice weighs 57 pounds, and a typical ice dam can weigh thousands of pounds.  Minimizing the stress placed on your roof is a great way to minimize the risk of leaking and cave-ins (the latter of which occur more frequently than you might think).

How do I know when roof snow removal is necessary?

A good rule of thumb is to get your roof cleared after every 6 inches of snowfall.  If you prevent too much snow from piling up on your roof, it’s much harder for ice dams to form and you can certainly stop worrying about any sort of roof cave-in.

Of course, it all depends: I’ve seen ice dams form with only a dusting of snow on the roof.  I’ve also seen roofs with mountains of snow remain free of ice dams.

Generally speaking, even though every roof is different, you’ll especially want to consider this “6-inch” rule of thumb if you’ve repeatedly had problems with ice dams in the past.

On the other hand, if you’ve never had an ice dam and your only concern is avoiding a roof collapse, then you might want to consider holding off on any roof snow removal until you’ve accumulated a foot or more of snow.

When deciding the right time to get roof snow removal, it’s also important to take into account how heavy the snow is.  Wet, heavy snow can weigh 6 or more times as much as lighter dryer snow.  One cubic foot of snow can typically range in weight from as little as 0.26lbs (light, dry snow) to as much as 1.66lbs. (heavy, wet snow).  If you step outside and pick up the snow and it seems heavy and wet, that’s one factor that might indicate you should get your roof cleared sooner rather than later.