Parts of a Roof – and Where Ice Dams Form
It’s important to know which parts of your roof ice dams tend to form on. That’s easier if you know the terms for the different parts of a roof and other features associated with the roof. On most roofs those include, in no particular order: gables, gable vents eaves / overhangs, valleys, soffits, fascia, gutters, ridge, ridge vent, chimney, hips, fields, vent pipe(s). Many roofs may also include skylights, dormers, cupolas, turbine vents, box vents, and other features.
Ice dams typically form on the overhangs and valleys of a roof. Of course, as they expand they can cover even more of your roof.
Here’s a diagram that shows in more detail what we’re describing: (click here to open the full-sized image in a new tab):