Ice dams in Aspen show up as a ridge of ice along the roof edge and a line of icicles that keeps growing. Behind that ridge, melted snow has nowhere to go. It backs up under the roofing and finds its way into the walls and ceilings. The ice is at the gutter, but the cause is usually higher up, in the attic.
Why Aspen roofs carry so much snow
Roofs here are built for a lot of weight. The Structural Engineers Association of Colorado's 2016 design snow load tables list a design ground snow load of 75 pounds per square foot for Aspen and 90 for Snowmass Village (Colorado Design Snow Loads, 2016). Pitkin County's building code points roof design back to those same values (Pitkin County Code, Title 11, version of Apr 26, 2025).
A roof built to carry that snow will hold it for weeks. That long cover of snow is exactly what an ice dam needs.
How an ice dam forms
The University of Minnesota Extension puts it simply: an ice dam needs snow on the roof, an upper roof surface above freezing, and a lower edge below freezing (UMN Extension, Dealing with and preventing ice dams).
Warm air leaking from the house into the attic warms the roof deck. Snow on the upper roof melts. The water runs down to the cold overhang and freezes again. Each day of melt adds to the ridge, and the pond behind it grows.
What heat tape can and cannot do
Heat cable along the eaves and in the gutters keeps a channel open so water can drain off. That helps on a roof that already dams every winter.
It does not change why the dam forms. If the attic stays warm, the snow keeps melting and the water keeps looking for a way in. Treat heat tape as a drain path, not a cure, and have it checked before the season so a dead run is found in October, not in a January thaw.
What snow retention is for
Snow guards and snow fences hold snow on the roof so it does not slide off in one sheet onto a walkway, a deck, a car or a lower roof. On many Aspen homes that matters more than the ice.
Snow retention keeps snow where it is. It does nothing to stop melting underneath. A roof with snow guards still needs a cold attic and clear drains.
The real fix starts in the attic
The long-term fix is a cold roof deck:
- Seal the air leaks into the attic around lights, vents, chimneys and attic hatches, so house heat stays in the house.
- Check the insulation. The National Weather Service suggests at least R-30 in the attic and calls R-38 preferable in northern climates (NWS, Preventing Roof Ice Dams).
- Keep air moving from the eaves to the roof vents so the underside of the roof stays close to the outside temperature.
A short checklist before the big snows
- Clear gutters and downspouts of leaves and needles.
- Test any heat cable and note which runs are off.
- Look at the eaves for last year's water stains or peeling paint.
- Walk the attic for frost, damp insulation or daylight around vents.
- Decide who watches the roof and clears snow when the house sits empty.
For a closed-up second home, that last step is the one that gets missed. Our Property Management team covers the house between visits, and our Roofing team handles repair and replacement built for snow load and fire code in Aspen, Snowmass and the Roaring Fork Valley.