On a recent visit to my house site, I saw huge accumulations of icicles and lots of evidence of ice damming. Many neighbors have installed heat tape on their eaves, an affront to elegant design in my opinion. I vowed to design and build a house that skirts the ice damming problem without resorting to active heating of the roof, a colossal waste of energy.
Here is a typical roof in the neighborhood. Icicles more than 10 ft. long hang from the eaves. There is probably significant ice damming at the roof edge. Dangerous, ugly, and a potential source of leaking and water damage.