Winter in Quebec is ruthless for residential and commercial roofs. One of the most insidious enemies is hailstorm (or “ice dam”) that forms at the edge of the roof. In P.G. Roofing., We often intervene to diagnose, prevent, and repair these problems. In this article, you will discover how ice dams form on roofs, why they are dangerous, and what sustainable solutions can be implemented.
Table of Contents
- What is an ice dam?
- Ice dams form because of uneven melting and refreezing of snow on a roof.
- The associated risks
- How to prevent ice dams
- Safe methods for eliminating them
- When to Call a Professional (and Why Toitures P.G.)
- Optimized FAQ (Questions People Ask)
- Call to action
What is an ice dam?
An ice dam is an accumulation of ice at the edge of the roof (at the eaves or gutters) that prevents meltwater from draining properly. The blocked water can then back up under shingles or membranes, causing water leaks. IKO Global+2One Stage Genie+2
2. Why do ice dams form?
Heat loss and snowmelt
When heat from the house escapes towards the roof (through poorly insulated attics or air leaks), it causes snow on the upper parts of the roof to melt. The resulting water flows down towards the edge of the roof, where colder areas will freeze the water, creating a dam.
b. Inadequate attic ventilation
Without proper ventilation (air intake and exhaust), heat accumulates in the attic, worsening snow melt. If the soffits or vents are blocked, air does not circulate well. L2 Roofing + 2 One Stage Genie + 2
c. Insufficient or improperly installed insulation
Insulation that is too thin or poorly installed can allow thermal bridges or air leaks. This facilitates localized roof warming. One Stage Genie+2 Benjel+2
d. Roof Design / Configuration
Certain roof sections, joints, overhangs, or “cold” areas (e.g., not exposed to the sun) can promote ice accumulation. A clogged or undersized gutter can also worsen the problem. IKO Global+1
3. Associated risks
- Water infiltration behind shingles or under roofing membrane
- Damage to attics, ceilings, walls, insulation
- Premature degradation of roofing materials
- Mold growth and condensation in the attic Stage Genie+1
- Loss of warranty if inappropriate ice removal methods are used IKO Global
4. How to prevent ice dams
Here are the most effective (and sustainable) methods:
4.1 Insulation and airtightness
- Install a well-sealed vapor barrier to prevent air leakage from the living space into the attic. Stage Genie+1
- Add or improve insulation with appropriate thermal resistance (R-value).
- Avoid blocking soffits with insulation
4.2 Adequate attic ventilation
- Have air intakes (e.g., soffits) and outlets (ridge vents, vents)
- Check that nothing is obstructing the ventilation channels
- Install mechanical ventilation devices (if necessary)
4.3 Protective membrane (ice & water system)
An “ice and water protector” or waterproofing membrane under the shingles near the eaves can limit infiltration during an ice dam. IKO Global+1
4.4 Heating wires / heating cables
Heating cables can be installed in gutters or on roof edges to melt ice as it forms or prevent it from forming. IKO Global+1
4.5 Snow Maintenance and Removal
- Shovel the snow regularly before it gets too thick.
- Leave a minimum layer of snow when plowing (do not scrape the roof) IKO Global+1
- Clean the gutters to facilitate drainage
5. Safe methods for removing an ice dam
When an ice dam has already formed, it can be removed, but with caution:
Recommended methods
- Warm water in a gentle stream run lukewarm water (not high pressure) over the ice to melt it gradually. IKO Global
- Heating cables (permanent or temporary installation) to help melt ice. IKO Global+1
Methods to avoid / prohibited methods
- Using a pick, shovel, or any sharp tool: this can damage the shingles or the membrane. IKO Global
- Using corrosive chemicals (salts, tablets): They may damage roofing materials and void warranties. IKO Global
When to Call a Professional — And Why Choose Toitures P.G.
- If the ice dam is significant or persistent
- If the roof or its materials are fragile
- To diagnose insulation, ventilation, and waterproofing in depth
- To ensure work is done to standard and safely
Why P.G. Roofing?
- Expertise in the Saint-Jérôme, Mirabel, Laval, and Montreal region toiturespg.ca
- Snow removal, ice removal, and roof repair services.
- Use of quality materials and adherence to best practices.
FAQs
What is an ice dam on a roof?
It's an accumulation of ice on the edge of the roof that prevents meltwater from flowing, which can cause leaks.
Why do I get ice dams every winter?
Often due to insufficient insulation, poor attic ventilation, or air leaks that warm the roof.
Are heating cables a permanent solution?
They can help, but they don't replace good ventilation and insulation. They must be installed well to be effective long-term.
Is it dangerous to remove an ice dam yourself?
Yes, because using inappropriate tools can damage the.