We have a cathedral ceiling-ed home up north that we use as a vacation home. During the winter we turn the furnace down to 10 degrees celcius. We have a steel roof and no eavestroughs. The house faces south and is set high up on rock. The last couple of winters we have had a large buildup of ice along the edge of the roof at the back at one end. Water has begun leaking down the wall and into the basement and we believe it is from this ice.
Answer:
I have a feeling there is little if any air going from the soffits up to the peak and then out. A ridge vent with baffles is all but mandatory on a cathedral ceiling-ed structure because other forms of vent simply permit air to move between one pair of rafters. You have to vent the whole thing. This will only get worse as time goes on.
