Why Do Ice Dams Form on Roofs and How Do They Cause Leaks?

An ice dam is a ridge of ice that forms at the edge of your roof, usually at the eaves or gutters. It happens when warm air from your attic heats the upper part of the roof, melting snow. The water runs down and refreezes where the roof surface is colder, typically near the overhang.

Over time, that refrozen water builds up into a solid barrier. As more snow melts above, the dam blocks the flow, and water pools behind it. Your roof is not designed to hold standing water, so the pressure pushes moisture up under the shingles and into the decking.

Watch for water stains on ceilings or walls, especially near exterior corners or along the roofline. You may also notice peeling paint, sagging drywall, or a musty smell in the attic. Icicles hanging from the eaves can be a clue, but they are not always a sign of a dam.

If you suspect a leak, act quickly. Move furniture away from the affected area and place a bucket under any drips. Turn off electricity to the room if water is near outlets or fixtures. Drying the space promptly can limit damage.

When an ice dam leak has already caused water damage, the cleanup involves more than drying the surface. Wet insulation, drywall, and wood framing may need to be removed and replaced to prevent mold. The pros use moisture meters and air movers to dry hidden areas thoroughly.

Start by calling a water damage professional to inspect the affected areas. They can identify the full extent of the damage and outline the steps for drying and repair. For immediate roof issues, emergency-roof-tarping can help protect your home until a roofer can make permanent repairs.

• Remove wet insulation and drywall
• Dry hidden cavities with air movers
• Inspect for mold growth
• Repair or replace damaged roof decking
• Check attic ventilation and insulation