Ice Dams by Alex Wilson If you mention ice dams around here, most builders groan and nod, with an I'm-all-too-familiar-with-thatproblem look. The past two winters, while great for the New England ski industry, have been among the worst in recent memory for ice dams. In this column, I'll take a look at the problem of ice dams: why they occur, and how you can avoid them (or at least reduce the potential damage). The Cause Ice dams form when snow melts on a building, allowing water to flow down the roof surface and freeze at the overhang. I've seen ice dams more than a foot thick. The ice acts as a dam, causing additional snowmelt to back up the roof-as much as