SEASONAL

Ice Dams: What Causes Them, What They Damage, and How to Remove Them Safely

By AJ Roofing | April 2, 2026 | Southwest Suburbs of Chicago

Every winter, AJ Roofing gets calls from homeowners who are watching water stain their ceilings. Ice dams are one of the most misunderstood hazards in our climate. If you have an active ice dam emergency, call our steam ice dam removal team immediately for safe, non-destructive clearing.

What Is an Ice Dam?

An ice dam is a ridge of ice that forms at the edge of a roof, blocking water from draining properly. Here's how it happens: Heat escaping from your living space through an under-insulated attic warms the upper portion of your roof deck. This melts snow on the upper roof. That water runs down the slope toward the eaves — but the eaves extend beyond the heated interior, so they stay at or below freezing. The water refreezes at the eave, building up a wall of ice.

As more snow melts above, water pools behind this ice wall. It has nowhere to go but sideways and backward — under your shingles, through your underlayment, and eventually into your home. The insidious part is that the leak point inside your home can be several feet from where the actual ice dam sits on the exterior.

Why Illinois Homes Are Particularly Vulnerable

The Chicago suburbs sit in a climate zone that cycles repeatedly through freeze and thaw throughout winter. Unlike northern Minnesota where it stays cold continuously, Illinois winters often see temperatures swing from single digits to the upper 30s and back within the same week. This cycle is precisely what creates the conditions for ice dam formation — warm enough to melt, cold enough to refreeze.

Older homes in communities like Homer Glen, Frankfort, and Mokena often have insufficient attic insulation by modern standards — R-19 or less when R-49 to R-60 is now recommended for our climate zone. Homes with complex roof geometry (multiple valleys, dormers, skylights) have more opportunities for ice accumulation and more vulnerable transition points for water entry.

What Damage Ice Dams Cause

The water intrusion from ice dams causes damage well beyond what you'd expect from a simple leak. Water that enters at the eave travels along rafters and decking, often appearing inside the home at an interior wall or light fixture far from the roof edge. This makes tracing the source difficult without professional inspection.

Inside your home, ice dam water saturates insulation (reducing its effectiveness permanently), stains and damages drywall ceilings, and creates the warm, damp conditions that mold requires. Mold growth can begin within 24 to 48 hours of moisture intrusion — and in a hidden attic or wall cavity, it can grow undetected for weeks.

On the roof itself, the ice physically forces apart shingle layers and damages the ice-and-water shield underlayment at the eave. After a severe ice dam winter, even a relatively young roof may need repairs at the eave zone. Gutters are also at risk — the weight of ice can pull gutters away from the fascia entirely.

Why DIY Removal Damages Your Roof

Homeowners typically try two DIY approaches: chipping at the ice with a hatchet or ice pick, or dumping rock salt on the dam. Both cause damage. Mechanical chipping gouges shingles and creates new leak points. Rock salt corrodes metal flashing, kills plantings below, and damages concrete and wood. Neither approach actually addresses the underlying problem.

Roof rakes — long-handled tools that let you pull snow off the roof from the ground — are a reasonable preventive measure if used carefully before ice forms. But once a dam has developed, a roof rake won't clear it safely.

Steam Removal: The Professional Standard

Professional ice dam removal uses low-pressure steam equipment that melts ice quickly without the mechanical force that damages shingles. Steam is effective, fast, and doesn't introduce the chemical problems of salt. Our crews create channels in the dam to allow trapped water to drain, then address the remaining ice carefully.

Steam removal is a temporary fix, however. The ice dam will return the next time conditions allow unless the underlying cause — heat loss through the attic — is addressed.

Long-Term Prevention: Insulation and Ventilation

The permanent solution to ice dams is keeping the roof deck cold in winter, which means preventing heat from escaping the living space into the attic. This involves two components: attic insulation (keeping heat in the living space) and attic ventilation (exhausting any heat that does reach the attic before it warms the roof deck).

AJ Roofing's roof inspections include an attic check for insulation adequacy and ventilation balance. If you've had ice dams form more than once, it's worth addressing the root cause — not just calling for steam removal every winter.