Prevention is key to keeping ice off your roof and water out of your home
How do ice dams form?
- Snow that stays on the roof for more than a few days, combined with freezing temperatures
- Warm air from your living space that leaks into the attic, causing snow to melt high on the roof
- Missing membrane protection beneath roof shingles along roof eaves causes melted snow to re-freeze
While you can't prevent snow from collecting on your roof, there are other things you can do to prevent ice dams from causing water damage to your house. Some homeowners choose to focus on reducing the amount of heat that escapes into the attic, warming the upper part of the roof deck and causing snow to melt evenly.
This type of ice dam prevention typically involves sealing air leaks in the attic floor and other solutions. Adequate attic ventilation is also important to keep the underside of the roof the same temperature as the outside air.
Another way to protect your home from ice dams and the damage associated with them is to make sure that an experienced roofing contractor installs a protective "ice and water" shield along your roof eaves, where the ice dams form.
Many building codes (this may vary by state and town) stipulate that this ice dam membrane protection must extend at least 24 inches inside the heated wall space of a house. However, older houses may not have such protection.