How Ice Dams Form
Ice dams are caused by a combination of factors unique to Colorado winters:
Warm air escaping from your living space into the attic melts snow on the upper roof. This is the #1 cause of ice dams.
The eaves (edges) of the roof are not heated, so melted water refreezes there, creating a dam of ice.
Denver averages 50-60 inches of snow per year. Heavy snow provides the water supply for ice dams.
Denver's frequent freeze-thaw cycles in winter accelerate ice dam formation. Daytime temperatures above freezing followed by nighttime freezing are the worst conditions.
Damage Caused by Ice Dams
Ice dams can cause significant damage if left untreated:
Water backs up under shingles and can enter your home through ceiling fixtures, walls, and attic insulation.
Water can damage drywall, insulation, paint, and personal belongings. Mold growth can follow if not addressed quickly.
The weight of ice can pull gutters and downspouts away from the roof, causing costly repairs.
Ice dams can cause moisture to penetrate fascia and soffit boards, leading to rot and structural issues.
Emergency Ice Dam Removal
If you have an active ice dam, here is what to do:
Contain the Water
Place buckets under leaks. Move furniture and valuables away from affected areas. Puncture sagging ceilings to release trapped water.
Call a Roofer
Contact a roofing professional for emergency ice dam removal. Many offer 24/7 service for this issue.
Use Calcium Chloride
You can temporarily melt ice dams by filling pantyhose or stockings with calcium chloride ice melt and placing them across the roof in a cross pattern. Do NOT use rock salt—it damages shingles.
Do NOT Use a Pickaxe
Striking ice with tools can damage shingles, puncture the roof deck, and void warranties. This is dangerous and can cause more damage than the ice dam itself.
Preventing Ice Dams Long-Term
The best way to deal with ice dams is to prevent them:
Adding insulation to your attic floor prevents heat from reaching the roof deck. This is the single most effective prevention method.
Seal gaps around light fixtures, plumbing vents, chimneys, and other penetrations in the attic floor. This stops warm air from entering the attic.
Proper soffit and ridge ventilation keeps the roof deck cold, preventing snow from melting. Add vents if your attic is poorly ventilated.
Electrical heating cables along the eaves can melt ice dams. These are a temporary solution and should be combined with insulation and ventilation improvements.
Using a roof rake, you can remove snow from the roof to prevent ice dam formation. This is a temporary fix and should be done carefully to avoid damaging shingles.
When Ice Dams Indicate Bigger Problems
Frequent ice dams may indicate deeper issues:
If ice dams form every winter, your attic insulation is likely inadequate. Adding insulation can solve the problem.
If ventilation is inadequate, even good insulation may not prevent ice dams. A professional can assess and upgrade your ventilation system.
Complex roof designs with multiple valleys and low slopes are more prone to ice dams. Proper flashing and ice/water shield installation can help.
Frequently Asked Questions
How do I remove ice dams from my roof?
Emergency removal should be done by a professional roofer. You can temporarily melt ice dams using calcium chloride (NOT rock salt) in pantyhose placed across the roof. Never use a pickaxe or strike ice, as this can damage your roof and void warranties.
How do I prevent ice dams?
The best prevention is improving attic insulation and sealing air leaks to prevent heat from reaching the roof deck. Proper ventilation is also critical. Heating cables along the eaves provide temporary relief but should be combined with insulation and ventilation improvements.
Is an ice dam the same as icicles?
Icicles are frozen water dripping from the roof edge. Ice dams are ridges of ice that form at the eaves, blocking water from draining off the roof. Both indicate heat loss from your attic, but ice dams cause active damage while icicles are mostly cosmetic.
How much does it cost to fix ice dams?
Emergency ice dam removal costs $500-$1,500. Long-term prevention (insulation, ventilation, heating cables) costs $1,500-$5,000 depending on the scope. The cost of prevention is far less than repairing water damage from ice dams.