Ice dams are accumulations of ice that form at the edges of a roof, usually from the constant thaw-freeze cycles in winter. They occur when snow on the roof starts to melt and the water runs down to the eaves and refreezes. Ice dams can cause water to back up under the shingles and leak into the attic or walls, leading to costly repairs. Preventing ice dams involves controlling attic heat and proper roof ventilation. Getting rid of existing ice dams requires some special techniques. Here’s a detailed guide on how to get rid of and prevent ice dams.
What Causes Ice Dams?
Ice dams form when the following conditions occur:
- Snow buildup – Ice dams always start with snow accumulating on the roof. Areas with substantial winter snowfalls are prone to ice dam issues.
- Heat escape – Heat from the home’s interior warms the underside of the roof. This causes snow on the roof to melt.
- Freeze-thaw cycles – Melting snow refreezes when it runs down the roof and reaches colder eaves and overhangs. This forms an ice dam that prevents further meltwater from draining.
- Poor insulation – Improper insulation allows interior heat to escape into the attic and warm the roof from below. This accelerates snowmelt.
- Inadequate ventilation – Lack of proper ridge and soffit ventilation prevents cold air circulation in the attic. This also raises roof temperatures.
The key factors are melted snow pooling at the eaves and refreezing. Preventing heat escape and ensuring ventilation inhibits ice dam formation.
How To Get Rid of Existing Ice Dams
If ice dams have already formed, act promptly to minimize water damage. Here are some effective removal methods:
Use ice melt products
- Spread ice melt on problem areas to melt through the ice. Calcium chloride or sodium chloride work best.
- Apply a channel of ice melt leading from the dam to the gutter. This creates a drainage path.
- Refill ice melt as needed until the dam is gone.
Remove snow
- Carefully shovel off all snow on the roof above and along the ice dam. This eliminates the water source.
- Use a roof rake to remove snow from hard-to-reach areas. Don’t risk falls by walking on inclined roofs.
- Hire professionals if roof access is hazardous. They can safely clear snow with rakes or other specialized tools.
Dislodge ice
- Gentle prying with a flat pry bar may detach the ice dam and break it up. Don’t damage roof shingles.
- A sledgehammer or ax can be used to carefully chip away at stubborn dams, working from the bottom up.
- Hire roofing contractors instead if you are uncomfortable with this method. Professionals have the proper tools and experience.
Install heating cables
- Heating cables designed for roofs can melt channels in ice dams. The cables run along the eave and loosen the ice’s grip.
- Hire an electrician to safely install these systems. The cables must be UL-approved for exterior use.
- Maintain heat cables through future winters to quickly eliminate new dams before they grow.
How To Prevent Ice Dams
Preventing ice dams involves controlling attic heat gain and improving ventilation:
Increase attic insulation
- Add extra insulation in the attic floor to resist heat loss through the ceiling below.
- Seal all penetrations and bypasses in the attic floor where warm interior air can enter.
- Insulate any hatch or pull-down stairwell that connects the attic to heated spaces.
Ventilate the attic space
- Install ridge vents along the roof peak to allow hot air to escape.
- Make sure soffit or eave vents permit sufficient intake of cold air.
- Check that ventilation paths aren’t blocked. Insulation should not restrict airflow.
Seal air leaks
- Caulk and weatherstrip all exterior wall and ceiling penetrations to reduce air leakage.
- Pay particular attention to sealing penetrations for utilities, plumbing, etc.
- Use spray foam for permanently sealing difficult to access gaps.
Manage moisture
- Vent all bathrooms, kitchens and laundry rooms to the outside to remove humidity.
- Consider installing a whole-house dehumidifier to reduce indoor moisture.
- Increase ventilation in musty basements and crawlspaces under the living space.
Common Questions about Ice Dams
What are signs of an ice dam?
Signs of ice dam formation include:
- Snow melting unevenly across the roof, with meltwater pooling at eaves
- A ridge of ice visible along the eaves or in gutters
- Icicles hanging from the eaves
- Signs of water damage like damp attic insulation or ceiling stains
Do heat cables permanently fix ice dams?
Heating cables effectively eliminate existing ice dams. However, they don’t prevent new ice dams from forming in other problem areas in future seasons. For a permanent solution, the root causes of improper attic heat and ventilation must be addressed.
What temperature causes ice dams?
Ice dams form when attic temperatures reach around 40-55°F. This allows just enough melting on the roof to create freeze-thaw conditions at the eaves. Keeping attics cooler is key for prevention.
Can ice dams be removed without damaging gutters or shingles?
It takes proper technique, care and the right tools to safely remove ice dams without roof damage. Consider hiring experienced professionals for difficult or hazardous dams.
How long does it take for ice dams to form?
Ice dams can form quickly under the right weather conditions. In a single overnight thaw-freeze cycle, enough snowmelt can pool and freeze at the eaves to start an ice dam. They continue growing as melting and refreezing persists.
Conclusion
Ice dams are a common roof problem in snowy northern climates, but they can be effectively managed. Start by acting promptly to remove existing dams using safe but effective removal techniques. For a long-term solution, address the root causes by improving attic insulation, sealing heat bypasses, and increasing ventilation. Stopping attic heat escape provides the best protection against recurring ice dams and costly roof damage. With proper prevention and vigilance, you can keep ice dams under control and protect your roof.