ICE DAMMING

What is Ice Damming? Causes, Effects, and Prevention

What is Ice Damming?

Ice damming is a common winter roofing problem that occurs when snow melts on a roof and refreezes at the eaves, forming a thick ridge of ice. This ice barrier prevents the proper drainage of melting snow, leading to water backing up under shingles. This can cause leaks, structural damage, and mold growth inside the home.

The Dangers of Ice Dams

Ice dams pose several risks to homeowners, including:

Roof Damage: Water trapped behind ice dams can seep under shingles, leading to rot and shingle deterioration.

Interior Water Damage: Once water penetrates the roof, it can damage ceilings, walls, and insulation, causing mold and mildew growth.

Gutter and Downspout Damage: The weight of the ice can pull gutters away from the roof, damaging the drainage system.

Safety Hazards: Large icicles formed by ice dams can break and fall, posing a risk to people and property below.

What Causes Ice Damming?

Several factors contribute to the formation of ice dams, including

1. Poor Attic Insulation

Insufficient or uneven insulation allows heat from the living space to escape into the attic, warming the roof and causing snow to melt unevenly. The melted snow then refreezes at the colder eaves, forming an ice dam.

2. Air leaks

Sealing of air leaks from the house into the attic prevents warm, humid air from entering the attic.

3. Inadequate Ventilation

Proper attic ventilation helps regulate attic temperatures. Poor ventilation leads to heat buildup in the attic, accelerating snowmelt on the roof.

4. Fluctuating Winter Temperatures

Temperature fluctuations, where the daytime temperature rises above freezing and drops at night, contribute to repetitive melting and refreezing cycles, promoting ice dam formation. This is a natural occurrence, and its impact can only be reduced by improvements to the roof covering and regular maintenance and inspections.

How to Prevent Ice Damming

Preventing ice dams requires a combination of proactive improvements on the roof and in the attic. Here are the most effective ways to protect your home:

1. Improve Attic Insulation

Adding high-quality insulation to the attic floor helps prevent heat from escaping into the attic.

2. Seal Air Leaks

The attic hatch or pull-down stairs must have proper weather stripping and sealing.

To minimize heat escape into the attic, seal gaps around chimneys, vents, plumbing, and wiring penetrations with spray foam or caulking.

Recessed lighting fixtures (use IC-rated fixtures that prevent heat loss) have a combustible clearance box with a vapour barrier seal around them.

3. Enhance Roof Ventilation

Ensuring your attic has sufficient ventilation will help maintain a consistent roof temperature. Install ridge, peak, or gable vents; ensure soffits are open on the exterior and that insulation baffles are in the attic to allow cold air flow and reduce excessive heat and condensation buildup.

Steps to take to deal with the ice dams until the root causes of the ice damming can be corrected

If ice damming is inevitable, you can limit the potential damage by taking some steps in the summer and performing winter maintenance.

1. Use Ice and Water Shield Membranes

When replacing or repairing your roof, install an ice and water shield underlayment along the eaves and valleys to prevent water infiltration.

2. Rake Snow Off Your Roof

Using a roof rake to remove snow from the edges of your roof can prevent excessive snow accumulation and help reduce the size of the ice dams.

3. Install Heated Roof Cables

Heating cables installed along the eaves help melt snow and prevent ice buildup.

4. Clean Gutters and Downspouts

Keep gutters and downspouts free of leaves and debris. Clogged gutters can increase the volume of ice dams.

5. Professional Roof Inspection and Maintenance

Scheduling regular inspections to identify damaged areas of the roof that need to be repaired because they are more likely to leak.

Conclusion

Ice damming is a preventable winter roofing issue that can lead to significant home damage if left unaddressed. You can protect your home from ice dams by improving insulation, correcting air leaks, and enhancing attic ventilation. You can also take steps to reduce the impact of ice dams until they can be prevented, such as installing ice and water shields, raking snow off your roof, installing heating cables and keeping gutters clean. If you experience frequent ice dam issues, consulting with a professional home inspector can help you find the best long-term solutions for your home.