The row bungalows here have a problem. Snow accumulates in valleys that are 20 ft wide at the bottom and 40 ft at the top. Snow slides occur that cause damage to cars parked below. Melting cables have been suggested.
Answer:
Melting cables will embrittle the shingles and you'll be replacing them prematurely. These are large areas you're talking about and about the best you'll do with them is to have a professional roofer monitor and clear them when necessary.
