If you want to prevent ice dams, your main priority should be keeping the whole roof cold and this can be achieved in a couple of different ways.
Metal Roof – First and foremost, a metal roof will be a great starting point. Although ice formations can occur on a metal roof, it is designed so that melting water cannot penetrate the surface and leak into the house. Furthermore, snow is likely to slide off the smooth surface as opposed to the surface on asphalt shingles.
Seal Air Leaks – For a smaller solution, you can ensure that heat isn’t getting to your roof. For example, you could seal all air leaks from the attic. Most commonly, these will appear around wiring, hatches, light fixtures, plumbing, and other vulnerable areas.
Check Insulation – If you have big spaces in your insulation, you’re at an immediate disadvantage so check for rips or maybe even try increasing the thickness around the chimney, on the attic floor, and the ductwork.