One way to find areas prone to ice dams is to look at the roof after the first heavy frost in fall or light snow. Note where the snow melts first and find out what is under that spot. One common sight in such conditions is a horizontal melt line across the roof of a 1 ½ storey house, where the short knee wall meets the ceiling. Other places would be beneath a roof-ducted exhaust fan, plumbing vent, under a skylight and above a leaky attic access hatch. The best prevention for ice damming is to seal all attic air leaks and insulate thoroughly.

Dark wall finishes can absorb solar heat and cause warm convection wall currents that may be to blame for ice dams. Sealing the associated soffit vents may help reduce the problem. However, other venting may still be required to ensure that the roof space is properly vented.