Updated October 2026

During an Ontario winter, snow accumulating on your roof may seem harmless. However, under certain conditions, melting and refreezing snow can create a problem known as an ice dam.

Ice dams can cause water to back up beneath roofing materials and enter your home, potentially damaging ceilings, walls, insulation and other parts of the building.

Many homeowners first discover a problem when they notice water stains on an upstairs ceiling or water dripping near an exterior wall.

Understanding how ice dams form, how to prevent them and how your home insurance may respond can help you avoid costly surprises.

What Is an Ice Dam?

An ice dam is a buildup of ice that forms near the lower edge of a roof, often along the eaves.

It typically develops when snow on the warmer portion of the roof melts and the resulting water flows toward the colder roof edge.

When the water reaches that colder area, it refreezes.

Over time, additional melting and refreezing can create a ridge of ice that prevents water from draining properly.

Water may then accumulate behind the ice dam and work its way beneath shingles or other roofing materials.

If that water enters the building, it can damage ceilings, walls, insulation and interior finishes.

Why Do Ice Dams Form?

Ice dams commonly develop when different areas of a roof have different temperatures.

Heat escaping from the living space into the attic can warm the upper portion of the roof enough to melt snow, even when the outdoor temperature remains below freezing.

The roof edge, which extends beyond the heated portion of the house, often stays colder.

As the melted snow reaches this colder area, it freezes again.

Several conditions can contribute to ice damming:

• Inadequate attic insulation.

• Air leakage from the living space into the attic.

• Poor attic ventilation.

• Heavy snow accumulation.

• Repeated freezing and thawing.

• Complex roof designs that allow snow and ice to accumulate.

Even a well-maintained home can experience ice damming during certain weather conditions, but proper insulation, air sealing and ventilation can help reduce the risk.

What Are the Warning Signs of Ice Damming?

Homeowners should watch for several signs during the winter.

Large Ridges of Ice Along the Roof Edge

A thick buildup of ice near the eaves may indicate that melting snow is refreezing rather than draining away.

Unusually Large Icicles

Icicles alone do not necessarily mean an ice dam has formed, but extensive ice buildup along the roof edge can be a warning sign.

Water Stains on Ceilings or Walls

Discolouration near exterior walls or upper-floor ceilings may indicate that water is entering beneath the roofing materials.

Damp Attic Insulation

Moisture in the attic may indicate roof leakage, condensation or ventilation problems that require investigation.

Peeling Paint or Damaged Drywall

Water entering through the roof may eventually cause paint to bubble, drywall to deteriorate or interior finishes to become damaged.

If you notice these signs, arrange for a qualified professional to investigate the cause.

Does Home Insurance Cover Damage Caused by Ice Damming?

This is one of the most important questions homeowners should ask.

The answer depends on the wording of your home insurance policy and the circumstances of the loss.

Some home insurance policies provide coverage for certain sudden and accidental water damage resulting from ice damming.

Other policies contain exclusions or limitations involving water entering through roofs, ice buildup, seepage or repeated water infiltration.

The fact that water entered your home does not automatically mean the damage is covered.

For example, if an ice dam causes water to enter your home and damage an interior ceiling, your insurance company will review the cause of the loss and the applicable policy provisions.

Depending on the coverage, the resulting interior damage may be insured.

However, the cost of correcting inadequate insulation, poor ventilation or deteriorated roofing materials may not be covered.

Home insurance is generally intended to respond to insured losses, not pay for routine maintenance or correct pre-existing construction deficiencies.

If you experience damage from an ice dam, contact your insurance broker or insurance company to determine how your policy applies.

Will Insurance Pay to Remove the Ice Dam?

Not necessarily.

Removing snow or ice from a roof is generally considered a maintenance or loss-prevention activity.

Insurance policies do not ordinarily pay for routine roof snow removal.

However, if an insured loss has occurred, the insurer may consider reasonable emergency measures taken to prevent further covered damage, subject to the policy terms and claims circumstances.

Before arranging expensive emergency work, contact your insurer where practical.

If immediate action is necessary to protect the property, document the situation and retain your receipts.

How Can I Prevent Ice Dams?

There are several measures homeowners can take to reduce the likelihood of ice damming.

Improve Attic Insulation

Proper attic insulation helps reduce heat transfer from the living space to the roof.

This can help maintain a more consistent roof temperature during cold weather.

However, simply adding insulation may not correct every ice damming problem.

Seal Air Leaks

Warm air can escape into the attic through gaps around plumbing penetrations, electrical fixtures, attic hatches and other openings.

Sealing these air leaks can be an important part of preventing ice dams.

Maintain Proper Attic Ventilation

Appropriate attic ventilation helps manage moisture and roof temperature.

Ventilation requirements depend on the design of the roof and attic.

A qualified roofing or insulation professional can assess whether your home's ventilation system is suitable.

Keep Eavestroughs Clear

Blocked eavestroughs can contribute to drainage problems and ice buildup.

Clean them in the fall before freezing temperatures arrive.

Although clean eavestroughs alone will not prevent all ice dams, proper drainage is an important part of roof maintenance.

Remove Excessive Roof Snow Safely

Reducing snow accumulation near the roof edge may help limit ice dam formation.

A roof rake designed for use from the ground may be appropriate for some homes.

However, homeowners should avoid climbing onto icy roofs or using ladders in hazardous winter conditions.

For significant snow accumulation or difficult roof designs, consider hiring a qualified contractor.

Should I Break the Ice Away From My Roof?

Generally, homeowners should avoid attempting to chip or break ice away from roofing materials.

Using axes, hammers, shovels or other sharp tools can damage shingles, flashing and eavestroughs.

There is also a serious risk of injury from falling ice, slippery surfaces and working at heights.

If an ice dam requires removal, contact a qualified roofing or ice-removal contractor who uses appropriate methods.

Steam removal or other professional techniques may be suitable in certain situations.

Avoid using open flames or uncontrolled heat sources to melt ice.

Do Heated Roof Cables Prevent Ice Dams?

Heated roof cables may help maintain drainage channels in certain problem areas.

However, they do not necessarily correct the underlying conditions that cause ice dams.

If warm air is escaping into the attic or the roof has inadequate insulation, ice damming may continue even with heating cables installed.

These systems also require proper installation and maintenance.

A more effective long-term approach is often to identify and correct the insulation, air leakage and ventilation issues contributing to the problem.

What Should I Do if Water Is Entering My Home?

If water begins entering your home because of an ice dam, take the following steps.

1. Protect Your Safety

Stay away from electrical equipment or fixtures affected by water. Do not climb onto an icy roof.

2. Document the Damage

Take photographs of visible ice buildup, water stains, wet materials and damaged belongings.

3. Prevent Further Damage

Move belongings away from the affected area and collect dripping water where it is safe to do so.

4. Contact Your Insurance Broker or Insurance Company

Report the damage promptly and ask about the claims process.

5. Arrange Qualified Assistance

A roofing contractor may need to address the ice buildup, while a restoration contractor may be required to dry affected interior materials.

6. Keep Your Receipts

Retain invoices for emergency services, inspections and temporary repairs.

Avoid undertaking major permanent repairs before discussing the situation with your insurance company, unless immediate work is necessary for safety or to prevent further damage.

What if the Ice Dam Was Caused by an Older Roof?

Roof condition can affect how an insurance company assesses a claim.

For example, an ice dam may cause water to enter through roofing materials that are already deteriorated or improperly installed.

The insurer may need to determine whether the damage resulted from a covered event, excluded deterioration or a combination of contributing factors.

The cost of replacing an aging roof is generally a homeowner maintenance responsibility.

If your roof is approaching the end of its useful life, having it inspected before winter can help identify problems that might otherwise become more serious.

Can Ice Damming Cause Mould?

Yes.

If water enters the attic, insulation, walls or ceilings and the affected materials remain damp, mould may develop.

This is one reason it is important to investigate water stains and leaks promptly.

Mould-related coverage varies considerably between insurance policies, and exclusions or limitations may apply.

Do not assume that all mould remediation expenses will be covered simply because the original moisture problem involved an ice dam.

Prompt drying and appropriate repairs can help reduce the risk of further damage.

Why Prevention Is Important

Ice damming is often associated with conditions that develop over time, including insulation deficiencies, air leakage, inadequate ventilation and roof maintenance problems.

Although an insurance policy may respond to certain resulting losses, preventing ice dams is generally preferable to dealing with water damage and repairs.

Homeowners should consider having their attic insulation, ventilation and roof condition assessed if ice dams repeatedly form during the winter.

Repeated ice damming may indicate an underlying problem that should be corrected rather than simply removing the ice each year.

Let Us Help You Understand Your Coverage

Ontario winters can be unpredictable, and ice damming can cause damage even when homeowners have taken reasonable precautions.

At L.D. Dermody Insurance Brokers, we encourage our clients to contact us if they have questions about water damage, roof coverage or how their home insurance policy may respond to an ice damming claim.

We can help explain the applicable policy provisions and assist you in understanding the claims process.

Remember: Preventing ice dams through proper roof maintenance, insulation and ventilation is often far less expensive than repairing the damage they can cause.

This article provides general information about ice damming and home insurance in Ontario as of October 2026. Coverage, exclusions, deductibles and claims settlement conditions vary by insurance company and are subject to the terms and conditions of the applicable policy.