What Causes Ice Dams on Colorado Roofs?

What the 2026-27 El Niño Forecast Means for Colorado Roofs

NOAA expects El Niño to remain strong through the 2026-27 winter. The current forecast does not tell us exactly how much snow Gunnison, Crested Butte, Durango, or another Colorado community will receive.

It does signal that homeowners should prepare for changing storm patterns and potentially challenging winter conditions.

The safest plan is to make sure the roof, gutters, valleys, snow retention, and heat cable are ready before the first heavy snowfall.

How Does an Ice Dam Form?

An ice dam begins when snow melts on a warmer part of the roof.

The water moves down the roof and reaches a colder eave, overhang, valley, or gutter. It then refreezes and begins creating a ridge of ice.

As more snow melts, water collects behind that ice. With nowhere to drain, the water may enter the roofing system or building as the freezing water expands into crevices and creates leak points as it melts again.

Common Warning Signs

Watch for:

Thick ice along the eaves
Large or recurring icicles
Frozen gutters or downspouts
Ice buildup in roof valleys
Uneven snowmelt
Water stains on ceilings
Damp attic insulation
Leaks following snowstorms

Small icicles do not always mean there is a major problem. Recurring ice buildup or interior moisture should be inspected.

What Causes Ice Dams?

Several conditions may contribute.

Heat Loss

Warm air escaping from the home can heat the roof deck and melt the snow above it.

Thin insulation, attic access doors, recessed lighting, exhaust vents, and other openings may allow heat to reach the roof.

Poor Drainage

Blocked gutters, frozen downspouts, poorly draining valleys, and low-slope transitions may prevent water from leaving the roof.

Roof Design

Dormers, multiple roof levels, long valleys, and shaded roof sections can create areas where snow and ice collect.

Changing Temperatures

Colorado’s freeze-thaw cycles allow snow to melt during warmer periods and refreeze when temperatures drop.

Do Metal Roofs Prevent Ice Dams?

Standing seam metal roofing sheds snow and water more efficiently than many other roofing materials. This can reduce snow accumulation and improve drainage.

However, ice may still develop when heat escapes through the roof, valleys do not drain correctly, gutters are blocked, or heat cable is missing from known problem areas.

Bottom Line

A quality metal roof helps manage snow and water, but the complete roofing and drainage system determines how well the home handles winter.

How to Prepare Before Winter

Before the 2026-27 El Niño winter, schedule an inspection of:

Roofing materials and seams
Flashing and penetrations
Roof valleys
Gutters and downspouts
Existing heat cable
Snow retention
Areas with previous ice or leaks

An ice dam does not automatically mean the entire roof needs replacement. A targeted repair, drainage improvement, or heat cable upgrade may solve the problem.

If the roof is aging or has widespread damage, replacement may provide better long-term value.

Schedule an Ice Dam Assessment

Axtell Mtn Construction installs roofing, heavy-gauge steel gutters, snow retention, and integrated heat cable systems built for Colorado mountain conditions.

If your home has recurring ice buildup or winter roof leaks, schedule an assessment before the next heavy snowfall.

Why Homeowners Across Southwest Colorado Trust Axtell

Replacing a roof is about more than selecting materials. It's about investing in a roofing system designed to perform in Colorado's demanding climate.

At Axtell Mtn Construction, we specialize in premium roof replacements throughout Durango, Gunnison, Crested Butte, Pagosa Springs, Bayfield, Cortez, Dolores, Telluride, Ouray, and Silverton. Every recommendation is based on your home's architecture, elevation, weather exposure, and long-term goals, ensuring your new roof delivers lasting performance for decades to come.

Through our partnership with Gunnison Sheet Metal & Roll Forming, we also provide locally manufactured standing seam, corrugated and propanel metal roofing systems that are precision fabricated for each project.

What is the main cause of an ice dam?
Ice dams commonly form when snow melts on a warmer part of the roof and refreezes when it reaches a colder section.
Can clogged gutters cause ice dams?
Clogged gutters can make ice buildup worse by preventing meltwater from draining. Heat loss, roof design, valleys, and changing temperatures may also contribute.
Will heat cables stop ice dams?
Heat cable can help keep drainage paths open. It works best as part of a complete system that includes proper roofing, flashing, gutters, insulation, and ventilation.