I'm really into ice this winter- Sarah, John & Dylan delight in cracking the thin layers of ice that seem to magically form on the edges of the driveway each night, especially as the ice is not really adhered to the asphalt and is hollow and cracks with a satisfying pop , I'm supposing it has something to do w/ the thermal mass qualities ie that the driveway continues to lose heat for much of the night actually keeping a very thin layer of water in contact with the surface from freezing - as I explained to them I remember my brother and I were incapable of walking to school without cracking the ice on every puddle wee encountered- Evidently, water continues to seep out of the snowbanks @ the driveway each night and freeze. I'm thinking that the snow exposed to the sun- even on a day like yesterday when the temp never got above 20 F, some melting occurs, the water percolates down through the snow, and being insulated by the snow drips out during the night, as opposed to the water that hits the bl;ack driveway during the day and evaporates.... So where is this taking me... I'm thinking that ice in the gutters and eaves is inevitable w/out some added heat- ie heat trace cable.. no roof is perfectly insulated and even one that is well insulated will still be subject to some melting from solar sources... so some water will reach the gutters which will be as cold as the outside air,- aluminum or copper sheet metal has no thermal mass qualities- and freeze and then a little more will hit the ice, and a little more......