How do you stop ice dams on a Colorado mountain home?

Why do ice dams form on mountain roofs?

• Two temperatures on one roof. The upper roof sits above 32F and the lower edge sits below 32F, so meltwater refreezes at the eave.
• Heat comes from the house. University of Minnesota Extension names air leakage from the house into the attic as the major heat path.
• Cold winters feed it. Jefferson County designs mountain homes for a 1°F winter temperature, so the eave stays below freezing for long stretches.

How do you prevent ice dams?

• Seal the attic first. DOE lists sealing leaks at wiring, light fixtures, plumbing stacks, flues, chimneys and attic hatches as step one.
• New builds get a full air barrier. Extension calls for a continuous air barrier through the ceiling with no air leakage into the attic.
• Ice barrier at the eave. IRC R905.1.2 runs it from the lowest roof edge to at least 24 inches inside the exterior wall line.
• What an ice barrier is. Two layers of underlayment cemented together, or a self-adhering polymer-modified bitumen sheet.
• Jefferson County requires it. Ice barrier underlayment is marked required in the county's climatic and geographic design criteria.

Ask the county building department for the permit history on a roof before you buy.

Does heat tape work on a roof, and what does it cost to run?

• It keeps a channel open. Heat cable melts a path at the eave and in gutters so water drains instead of backing up.
• It draws 5 to 8 watts per foot. 100 feet of cable draws 500 to 800 watts while running.
• A month adds up. 100 feet running nonstop for 30 days uses 360 to 576 kWh.
• What that costs on CORE Electric. At CORE's $0.1155 per kWh residential energy rate for 2026, 360 to 576 kWh runs $41.58 to $66.53 before demand charges.
• Rates went up. CORE raised rates 6.7% on average starting with January 2026 bills, and added an on-peak demand charge of $5.47.

Put heat cable on a thermostat or timer. Ask the seller for last winter's electric bills.

How do you keep pipes from freezing in a mountain second home?

• Keep the heat on. Jefferson County's heating design temperature is -7°F below 7,400 feet and -11°F above it, so an unheated house freezes.
• Stop the air leaks. The same attic sealing that stops ice dams keeps cold air off pipes in outside walls.
• Have someone check the house. A property manager walking the house after each storm catches a frozen line before it floods.

Roof snow removal is work for an insured crew with fall protection, not the owner on a ladder.