Ice dam (roof)

An ice dam is a ridge of ice that forms at the edge of a roof, typically on a sloped roof. It prevents melting snow and ice from draining properly off the roof. The water backs up behind the dam and can leak into a home, causing damage to walls, ceilings, insulation, and other areas.

Formation:

Ice dams are primarily caused by uneven roof temperatures. Heat escaping from the home's interior warms the roof, causing snow to melt. This melted snow then flows down the roof until it reaches the colder eaves, which are typically not warmed by the house's interior. At the eaves, the water refreezes, forming a dam of ice. As more melting snow reaches the dam, it continues to freeze, expanding the dam and backing up the water.

Damage:

The primary damage caused by ice dams is water infiltration into the home. Water trapped behind the ice dam can seep under roof shingles or through other roof penetrations, eventually finding its way into the attic, walls, and ceilings. This can lead to:

• Structural damage: Rotting wood, damaged drywall, and compromised structural integrity.
• Insulation damage: Wet insulation loses its effectiveness, leading to higher energy bills and potential mold growth.
• Mold and mildew growth: Moisture creates an environment conducive to mold and mildew, posing health risks.
• Damaged ceilings and walls: Water stains, peeling paint, and sagging ceilings.
• Damaged exterior finishes: Paint damage or staining to soffits and fascia.

Prevention:

Preventing ice dams involves reducing heat loss from the home and ensuring proper roof ventilation. Effective prevention measures include:

• Improving insulation: Adding insulation in the attic and walls reduces heat escaping from the home.
• Sealing air leaks: Sealing gaps around pipes, wiring, chimneys, and other penetrations prevents warm air from escaping into the attic.
• Ensuring proper ventilation: Adequate attic ventilation helps keep the roof temperature consistent and prevents warm air from becoming trapped in the attic.
• Removing snow from the roof: Raking snow off the roof, especially near the eaves, can help prevent ice dam formation. This should be done carefully and safely from the ground using a roof rake designed for this purpose.
• Installing heat tape: Electric heat tape or cables can be installed along the eaves to melt snow and ice and create a channel for water to drain. However, this is considered a short-term solution and should be used with caution due to energy consumption and potential fire hazards.

Removal:

If an ice dam has already formed, removal can be necessary to prevent further damage. Safe removal methods include:

• Removing snow from the roof: As mentioned above, removing snow reduces the amount of water contributing to the dam.
• Creating channels for water to drain: Carefully chipping away at the ice dam to create channels for water to drain. Extreme caution is required to avoid damaging the roof or gutters. Professional assistance is often recommended.
• Using ice melt products: Ice melt products designed for roofs can be used to melt the ice dam, but care should be taken to avoid damaging the roof or surrounding vegetation.
• Steam thawing: Professionals can use steam to melt the ice dam safely and effectively.

Important Considerations:

Attempting to remove an ice dam can be dangerous, especially when working on a ladder or on a slippery roof. It is often best to consult with a professional roofing contractor or ice dam removal specialist. Avoid using sharp tools or hammers that could damage the roof.