Quick Answer

Ice dams are ridges of ice that form at the eaves of your roof, preventing melting snow from draining properly. This trapped water can then seep under your shingles, leading to significant water damage inside your home, including stained ceilings, damaged insulation, and even structural issues. The safest way for a homeowner to manage existing ice dams involves carefully removing snow from the roof 's edge and strategically applying ice melt. Long-term prevention focuses on improving attic ventilation and insulation to keep the roof deck evenly warm.

The Problem

Ice dams occur when the upper, warmer parts of your roof melt snow, but the water freezes again when it reaches the colder eaves, often directly above unheated overhangs. This continuous cycle builds up a barrier of ice that prevents further meltwater from draining off the roof. As a result, water pools behind the dam, finding its way under shingles, into your attic, and down into the walls and ceilings of your home. This can lead to costly repairs, mold growth, and decreased energy efficiency.

Step-by-Step Fix

Safety Note: Always be extremely cautious when working on a roof, especially in icy conditions. Consider wearing a safety harness and always have someone spot you from the ground. Avoid climbing onto a slippery roof. If you cannot safely reach the ice dam from the ground or a sturdy ladder, call a professional.

1. Clear Snow from the Roof: Use a roof rake with an extendable handle to carefully pull fresh snow off the first few feet of your roof, starting from the eaves and working your way up. This removes the source of melting water that feeds the ice dam. Avoid aggressive scraping that could damage shingles.
2. Create Drainage Channels: For existing ice dams, fill old knee-high stockings or tube socks with calcium chloride ice melt (rock salt can damage your roof and landscaping). Lay these socks perpendicular to the ice dam, across the dam and extending into the gutter. The calcium chloride will slowly melt channels through the ice, allowing trapped water to drain. DO NOT use chisels, hammers, or other blunt objects to break ice, as this can severely damage your roof.
3. Continue Monitoring: As the ice melts, you may need to reposition the socks or apply more if the dam is particularly thick. Continue to remove new snow promptly after storms.

Common Causes

• Uneven Roof Temperatures: The most common cause is a roof that is warmer at the ridge and colder at the eaves. This is often due to poor attic insulation, allowing heat from the living space to escape into the attic and warm the roof deck.
• Insufficient Attic Ventilation: Inadequate ventilation prevents superheated air from exiting the attic, leading to warmer roof surfaces. Soffit and ridge vents need to be clear and unobstructed.
• Blocked Vents: Soffit vents blocked by insulation can trap heat, contributing to an uneven roof temperature.
• Warm Air Leaks: Gaps around unsealed attic hatches, poorly sealed light fixtures, or exhaust fans venting into the attic can allow warm, moist air to escape and heat up sections of the roof.

Tips & Prevention

• Improve Attic Insulation: Ensure your attic has adequate insulation (check your local building codes for recommended R-values) to minimize heat transfer from your living space to the attic.
• Enhance Attic Ventilation: Make sure your attic has a balanced system of soffit and ridge vents to allow cold air in and warm, moist air out. Ensure vents are not blocked by insulation.
• Seal Air Leaks: Caulk and seal any penetrations in your attic floor or ceiling, such as around light fixtures, plumbing stacks, and attic access points, to prevent warm air from rising.
• Regular Gutter Cleaning: Keep gutters and downspouts clear of leaves and debris before winter to ensure proper drainage when snow melts.
• Prompt Snow Removal: After a heavy snowfall, use a roof rake to pull snow off the lower 3-4 feet of your roof to prevent ice dam formation.

When to Call a Professional

If ice dams are extensive, difficult to reach safely, or you notice water stains inside your home, call a licensed roofing professional. They have the experience and equipment to safely remove ice and assess any damage. For persistent ice dam issues, a professional can also evaluate your attic's insulation and ventilation to recommend long-term solutions.