Ice damming is a phenomenon that occurs when snow accumulates on the roof at the point where the warm side of the roof meets the cold side of the roof. The area I am describing is where the outside wall meets the attic space or just beyond where the soffit ends.
The snow higher on the roof will melt and run down the roof with part of it refreezing just a couple of feet above the eaves trough, creating a dam effect. The water just above the dam may then work its way under the shingles.
This issue may present itself as just a stain or dripping at the ceiling near the wall edge or at an exterior door or window on the top floor.
Most newer houses will have an Ice and Water Shield for the first few feet above the roof edge, that may help keep water from entering the home. The only problem is that the ice and water shield tends to end at the area where the problem may occur.
Ice Damming may occur higher up on the roof when certain conditions exist:
- Inadequate or inconsistent insulation.
- Poor attic ventilation.
- Air leakage from the house into the attic.
There are also roofs that may be more susceptible to ice damming, such as low slope roofs or roofs that have poorly designed valleys. Your Canspec inspector will inform you of vulnerable designs when inspecting a home.
Many products exist that may help to alleviate symptoms of ice damming:
- A roof rake.
- Heating coils (use a lot of energy).
- Ice melting chemicals.
- Shoveling the roof (high risk of injury).
Using axes and shovels and even rakes to break up ice dams can cause a lot of damage to the shingles. I have heard of someone having success putting ice melting chemicals in their eaves trough (in a nylon material).
None of these solutions really gets to the root cause of the problem and will not be as reliable as just solving the problem.
When investigating an ice damming issue the first place to start is in the attic above where the water is presenting itself. How is the insulation, and ventilation in the area?
The single biggest factor in elimination of ice damming is ensuring that warm air from the house is not entering the attic. Warm air can enter the attic from improperly sealed attic hatch, pot lights, plumbing vents, chimneys etc…..
Ice damming can be corrected by a home owner, but you have to be aware of things like how to walk in the attic and how to spot design issues and poorly sealed areas.
If in doubt I would always encourage a home owner to contact a specialist.
*When purchasing my own home, I entrusted the services of Canspec to carry out the Home Inspection and was 100% satisfied with their work and communication as a Buyer!
