Many homeowners whose roofs had ice damming issues last winter should now be looking into putting ice and water shields. This product, made out of rubberized asphalt, will adhere more to the shingle nails, resulting to a tighter fit than a metal flashing. Different roof contractors may have different opinions on how much ice shield to lay down. The decision depends on the design of your roof. The more areas you cover, the higher the cost would be. Here are the common places where ice shield coverage is needed:

1. Valleys. The space where two slopes meet can be a problem area. If this is the source of the leak and water damage you had, there is no avoiding the ice shield here.

2. Above the eaves. Since the ice dams occur near the edge of the roof where the temperature is likely lower, you will need the additional protection here. Proper insulation is still key to avoid ice dams in the first place.

3. At all sides. If your contractor is proposing coverage on the whole side, it can only mean that the slope of your roof is not too steep, and not because your contractor is out to rip you off. The flow of water in a flat roof can be slower and would tend to seep into the shingles.

Source: Askmehelpdesk.com