How Ice Dams Form — And How to Help Prevent Them | Nexus Home Inspections
Winter weather in Central New York creates the ideal environment for ice dams — a leading cause of winter roof leaks and attic damage. At Nexus Home Inspections, we often see firsthand how ice dams begin and what can be done to stop them before they cause significant problems.
❄️ What Is an Ice Dam?
An ice dam is a ridge of ice that forms along the edge of a roof, typically near the gutters or eaves. When melting snow gets trapped behind this ice, the water can back up under roofing materials and leak into the home.
❄️ How Ice Dams Form
Ice dams don’t happen randomly — they follow a predictable process tied to roof temperature.
1. Warm air escapes into the attic
If insulation or air sealing is inadequate, heat from inside the home rises and warms the attic.
2. Snow melts on the upper part of the roof
This creates water runoff even when outdoor temperatures are below freezing.
3. Water refreezes at the colder roof edges
The eaves and gutters remain cold, causing the runoff to freeze into solid ice.
4. Ice accumulates and blocks drainage
This growing ridge of ice becomes a dam.
5. Water backs up under shingles
This can damage the roof, insulation, attic, and interior ceilings.
❄️ How to Help Prevent Ice Dams
Prevention focuses on one main principle: keep the roof cold and the attic sealed.
1. Improve Attic Insulation
Better insulation reduces heat loss into the attic and minimizes uneven roof temperatures.
2. Seal Attic Air Leaks
Warm indoor air shouldn’t escape into the attic. Seal openings around:
- Light fixtures
- Chimney chases
- Plumbing penetrations
- Ductwork
- Attic pull-down stairs and hatches
3. Ensure Proper Attic Ventilation
Good airflow keeps the attic the same temperature as the outdoors, reducing melt-and-freeze cycles.
4. Keep Gutters Clean
While gutters don’t cause ice dams, clogged ones can make water buildup worse. Clean gutters help melted snow drain effectively.
5. Use a Roof Rake After Snowfalls
Removing the first 2–3 feet of snow along the roof edge helps prevent the melt-refreeze cycle that starts ice dams.
6. Add Ice & Water Shield When Re-Roofing
An ice & water barrier membrane under the shingles provides extra protection in case ice dams do form.
❄️ Final Thoughts
Ice dams can cause serious problems during our Central New York winters, but with proper insulation, ventilation, and maintenance, homeowners can greatly reduce the risk.At Nexus Home Inspections, we help identify attic and roofing issues before they turn into expensive repairs. If you're concerned about ice dams or want a professional evaluation, we’re here to help.📍 Serving Cortland • Ithaca • Binghamton & Surrounding Areas
📞 607-423-4202
📧 nexushomeinspections@gmail.com
🌐 Nexus Home Inspections — At the Center of Your Real Estate Transaction
❄️ What Is an Ice Dam?
An ice dam is a ridge of ice that forms along the edge of a roof, typically near the gutters or eaves. When melting snow gets trapped behind this ice, the water can back up under roofing materials and leak into the home.
❄️ How Ice Dams Form
Ice dams don’t happen randomly — they follow a predictable process tied to roof temperature.
1. Warm air escapes into the attic
If insulation or air sealing is inadequate, heat from inside the home rises and warms the attic.
2. Snow melts on the upper part of the roof
This creates water runoff even when outdoor temperatures are below freezing.
3. Water refreezes at the colder roof edges
The eaves and gutters remain cold, causing the runoff to freeze into solid ice.
4. Ice accumulates and blocks drainage
This growing ridge of ice becomes a dam.
5. Water backs up under shingles
This can damage the roof, insulation, attic, and interior ceilings.
❄️ How to Help Prevent Ice Dams
Prevention focuses on one main principle: keep the roof cold and the attic sealed.
1. Improve Attic Insulation
Better insulation reduces heat loss into the attic and minimizes uneven roof temperatures.
2. Seal Attic Air Leaks
Warm indoor air shouldn’t escape into the attic. Seal openings around:
- Light fixtures
- Chimney chases
- Plumbing penetrations
- Ductwork
- Attic pull-down stairs and hatches
3. Ensure Proper Attic Ventilation
Good airflow keeps the attic the same temperature as the outdoors, reducing melt-and-freeze cycles.
4. Keep Gutters Clean
While gutters don’t cause ice dams, clogged ones can make water buildup worse. Clean gutters help melted snow drain effectively.
5. Use a Roof Rake After Snowfalls
Removing the first 2–3 feet of snow along the roof edge helps prevent the melt-refreeze cycle that starts ice dams.
6. Add Ice & Water Shield When Re-Roofing
An ice & water barrier membrane under the shingles provides extra protection in case ice dams do form.
❄️ Final Thoughts
Ice dams can cause serious problems during our Central New York winters, but with proper insulation, ventilation, and maintenance, homeowners can greatly reduce the risk.At Nexus Home Inspections, we help identify attic and roofing issues before they turn into expensive repairs. If you're concerned about ice dams or want a professional evaluation, we’re here to help.📍 Serving the Central New York & Surrounding Areas
📞 607-423-4202
📧 nexushomeinspections@gmail.com
🌐 Nexus Home Inspections — At the Center of Your Real Estate Transaction
