Ice dams are formed by continual thawing and refreezing of melting snow. Large masses of ice develop as snow on the upper part of the roof melts. The water runs under the snow and refreezes at the edge of the roof. Additional snow melts and forms pools against the dam gradually causing water to back up the roof often getting under the shingles and eventually leaking into the house.
- Poor or non existent vapour barrier which allows heat to escape into the attic.
- Air leakage through light fixtures, plumbing stacks, attic access hatches and fan vents etc.
- Insufficient attic insulation allowing warm air into the attic and melting the snow.
- Inadequate attic ventilation.
- Bright sunshine melting the snow;
- Naturally occurring ice accumulation due to various weather conditions.
How to avoid ice dams:
- Eliminate or reduce air leakage into the attic by installing a vapour barrier or sealing air leaks
- Improve attic insulation keeping the attic space cool, thereby reducing the amount of melting snow
- Lower the humidity level in the living space
Are there solutions to my ice dam problems?
Yes there are but it is usually very expensive to solve. Ice dam and condensation problems occur because warm moist air is leaking into the attic from the living space. You must eliminate these air leaks to eliminate the problem. The only way to do this is by installing a proper vapour barrier. We can do this by cleaning out the cavities and spraying in a polyurethane insulation. This will seal the air leaks and insulate the attic. You could expect to pay anywhere from $5000.00 to $20,000.00. You can do a less thorough job by sealing up light fixtures, attic access hatches and other sources of air leaks. You could also try lowering the humidity level in the living space.
Don't wait until your roof leaks before replacing your shingles. Your shingles are like tires on a car. They wear out gradually over time and at some point they become unable to perform they way they were designed to. If you leave it too long not only will you be replacing the shingles but you will also have interior repairs to deal with, possible deck rot to replace and wet insulation in the attic.
You should consider having your roof inspected or your shingles replaced if you have:
- worn valleys
- roof leaks (waited too long)
- missing or damaged shingles
- shingles that are 15 to 20 years old
- severe curling (some curling is natural in the aging process)
- excessive granule loss (some granule loss is normal especially with new shingles)
- a desire to upgrade and change the appearance of your home with architectural shingles
- severe ice dam or condensation problems that require extensive repairs to rectify the problems