Snow, ice dams and freeze protection for Colorado homes

How ice dams form

An ice dam is a ridge of ice at the roof edge that stops melting snow from draining. It needs three things: snow on the roof, a roof surface above freezing higher up, and a roof edge below freezing. Warm air leaking from the house into the attic heats the upper roof deck. Snow there melts, water runs down under the snow blanket, reaches the cold overhang that sits outside the heated envelope, and freezes. Each cycle adds to the ridge, and eventually water pools behind it and works up under the shingles.

Colorado's sunny winter days speed this along, especially on south-facing slopes and on roofs over vaulted ceilings or poorly sealed attics. You will often see dams on one part of a house and not another, which is a useful clue about where heat is escaping.

Diagnose what you are seeing

Pick everything that matches your house. The tool explains what each symptom usually points to.

Fix it in the attic, not on the roof

The durable fix for ice dams is to keep the attic cold: seal the air leaks from the house, add insulation where it is thin, and make sure the attic is ventilated as designed. Air sealing comes first, because a lot of attic heat arrives by moving air, not by conduction through insulation. Common leaks include recessed light cans, bath fan housings, plumbing and wiring holes in the top plates, chimney chases, and the attic hatch itself.

Once the leaks are sealed, insulation does more good. Many older Front Range homes have far less attic insulation than current energy codes ask for in new construction. An energy auditor or insulation contractor can measure what you have and recommend a target. Some Colorado utilities have offered rebates or audit programs over the years; check your utility's site for what is current.

Protect the eaves when the roof is replaced

When a roof is replaced, the eaves deserve extra protection. Self-adhered ice barrier membrane under the shingles along the eaves is a standard defense in snow country, and building codes in many jurisdictions require it in cold climates. Ask any roofing bidder how far up the roof they run the membrane, whether it covers valleys, and how they handle the drip edge and gutter apron. Our hail and roof guide covers other questions for roof replacement.

When ice is already there

If you have an active leak, the priority is limiting damage. Catch the water, move belongings, and photograph everything. A long-handled roof rake used from the ground can pull the lower few feet of snow off the roof so less melt reaches the dam. Do not climb an icy ladder and do not chip at the ice; it damages shingles and gutters.

Professional ice-dam removal typically uses low-pressure steam, which cuts channels through the ice without harming the roof. If you hire it out, ask how they protect shingles and gutters, and whether they carry liability insurance. The contractor vetting guide covers what to confirm.

Heavy snow on roofs and trees

Late-season storms on the Front Range often bring dense, wet snow that is far heavier than January powder. Most homes built to code handle normal loads, but drifting near higher walls, valleys and lower roofs can concentrate weight. Signs of trouble include sagging ceilings, doors that suddenly stick upstairs, or cracking sounds. If you see those, get people out of the area and call a professional.

Trees are more often the problem. Gently brush heavy snow off shrubs and young trees, especially those still in leaf during an early fall storm. Keep away from limbs over power lines and call the utility for those.

Pipes and hose bibs

Arctic air pushes down the Front Range a few times most winters, and the pipes that freeze are predictable: those in exterior walls, crawl spaces, garages, and cabinets on outside walls. During cold snaps, open cabinet doors, let a faucet on an exterior wall drip, and keep the garage closed.

1. Disconnect hoses in OctoberA frost-free sillcock only works when the hose is off. Store hoses and splitters indoors.
2. Find the main shutoffMake sure everyone in the house knows where it is and that it turns.
3. Insulate exposed pipesFoam sleeves on pipes in garages and crawl spaces are cheap and quick.
4. Plan for tripsKeep heat on, and arrange for someone to check the house during long absences.

If a pipe freezes, shut off the water before it thaws if you can, open the faucet it serves, and warm the area gently with a hair dryer or space heater placed at a safe distance. Never use an open flame. If it has already split, a licensed plumber is the right call; plumbers are licensed by the state in Colorado.