Seasonal

Ice Dam Prevention: Why Eaves Ice Up and How to Stop It

By Overland Park Roof Repair · November 2, 2026 · 9 min read

Ice dams in Overland Park usually show up the week after the first real snow, and they always start the same way: a two-foot row of icicles along the eave, and a wet patch on the ceiling near the outside wall. The homeowner wants to know what is wrong with the roof.

Usually nothing. The roof is doing what it was built to do. The problem is that the attic is warm — and attic heat loss, not the shingles, is what this post is about.

How ice dams in Overland Park form

1. Snow lands on the roof and sits there. Johnson County gets around 15 inches a winter, most of it in two or three events that stay on a roof for days.
2. Heat leaking out of the living space warms the underside of the deck. The snow touching that deck melts, even on a cold day.
3. The meltwater runs down under the snow blanket until it reaches the eave — the last two or three feet of roof that hangs past the exterior wall and has nothing warm under it. There it refreezes.
4. That refrozen ridge grows. Water backs up behind it, sits in a pond several inches deep, and finds its way under the shingle courses. Shingles shed water running downhill; they do not hold back standing water.

That is why a brand-new roof can get an ice dam and a 20-year-old roof next door can go a whole winter without one. It tracks the attic, not the shingles.

Where it shows up first inside

• A stain on the ceiling within two feet of an exterior wall
• Water running down the inside of a window frame on the top floor
• Damp insulation in the attic along the outer edge, where the roof meets the top plate
• Paint bubbling at the top of an interior wall
• Nail heads in the attic frosted white on a cold morning

The houses that get them here

Two Overland Park patterns account for most ice dams here. The 1960s and 1970s ranches north of I-435 — the streets off Nall, Antioch and Roe — have shallow pitches, narrow overhangs, and a soffit that was never vented or has since been painted and insulated shut. Warm attic, no cold air moving through it.

The second pattern is newer: the 1990s and 2000s two-stories in the Blue Valley subdivisions with cathedral ceilings, recessed can lights, and a big open bonus room over the garage. Every can light is a hole into the attic. A bonus room over an unheated garage tends to ice at the eave every winter until somebody air-seals it.

Ice dam prevention: what actually fixes it

Ice dam prevention in the Kansas City area comes down to keeping the roof deck cold. In roughly the order most roofers and energy auditors would tackle it:

Air sealing is unglamorous and it is where the money should go first. Bath fans venting into the attic instead of through the roof, an open chase around the furnace flue, an attic hatch with no weatherstrip, twelve can lights that are not IC-rated and airtight — those are the holes. Blowing another foot of insulation over the top of them without sealing them just filters the warm air on its way up.

A cold-morning attic check you can do yourself

The best time to look is early on a morning after a cold night, with snow still on the roof. Take a flashlight and a phone for photos, and step only on the joists.

1. Look at the nail tips poking through the deck. White frost on them means warm, damp air is reaching the underside of the roof.
2. Follow the warm spots. Look above the bath fans, the can lights, the furnace flue and the attic hatch. Dark or dirty insulation there is a sign air has been moving through it for years.
3. Check the eaves. Shine the light toward the outside walls. If insulation is packed against the deck and you see no daylight from the soffit, the intake is blocked.
4. Measure the insulation. A tape measure stuck down to the ceiling drywall in three or four places tells you whether you are anywhere near R-49.
5. Go outside and compare. Bare patches on the roof while the neighbors still have snow show where heat is getting out.

Write down what you found. It turns a vague "we get ice dams" into a list a roofer or energy auditor can price.

Questions to ask before you pay for a fix

• Will you air-seal the attic before adding insulation, or only blow more in?
• Which bath fans end in the attic, and will they be ducted outside?
• Are the soffits open to the attic, and will the baffles keep insulation off the deck?
• If you recommend heat cable, what does it cost to run, and what would fix the cause instead?
• On a re-roof, how far up from the edge will the membrane run?

A good answer names the holes, not just the product.

What not to do

Do not chip at it. Every winter somebody takes a hammer, a hatchet or a garden spade to the ice at the eave and puts a hole through the shingles, the drip edge or the gutter. You will be paying for that in April.

Do not throw salt tablets in a nylon stocking up there unless you accept what calcium chloride does to aluminum gutters and to the plantings underneath.

Do not run a pressure washer or a torch. Both get tried, and both do damage.

Do rake the first three feet with a roof rake from the ground if you can reach safely, before the snow has a chance to melt and refreeze. That is the one homeowner move that genuinely helps mid-storm.

If it is already leaking

Get a bucket under it, pull the wet insulation back so the ceiling can dry, and call a roofer who will come look at the attic, not just the roof. If you need emergency roof repair, Overland Park roofers in January mostly steam a channel through the dam so the pond drains, then come back in warm weather to fix the cause. Steaming runs $400–$900 a visit and it is a stopgap, not a repair.

The permanent fix gets scheduled for a dry stretch, and it usually involves the attic more than the roof. The roof repair page covers how a roofer traces an eave leak from the inside, and the earlier post on gutter and roof-edge repairs covers what the eave assembly should look like when it is right.

If you are replacing the roof anyway

Ask every bidder how far up the roof the ice-and-water membrane will run from the drip edge — ideally past the interior wall line. It is $300–$700 in materials on a typical house, and it is the difference between an ice dam being an annoyance and an ice dam being a ceiling repair. What the code requires at the eave depends on your city, so check with the City of Overland Park's building department (or your city's), and make sure the permit is on the quote. If the membrane is not on the quote, it is not on the roof. The roof replacement page lists what a complete replacement should include, and the cost page has the numbers.

Common questions

Do heat cables stop ice dams?

They keep a channel open so meltwater can drain, which can stop a dam from backing water into the house. They do not fix the attic heat loss that causes the dam in the first place, and they cost electricity every time they run. Think of heat cables as a patch for an eave you cannot otherwise fix, not as the solution.

Should I rake snow off my roof?

Raking the bottom three feet from the ground, with a roof rake and a safe footing, is a sensible move after a heavy snow. It removes the snow that would melt and refreeze at the eave. Never climb onto a snowy roof or work from a ladder on ice; leave anything above the first few feet alone.

Do new shingles stop ice dams?

No. A new roof with membrane at the eaves can keep a dam from leaking into the house, but the dam still forms if the attic is warm. Fix the air leaks and the ventilation first, and the ice usually stops building at the eave.

Why do icicles form along my gutters?

Long icicles mean meltwater is reaching the cold eave and refreezing, which usually points to heat escaping into the attic. A few short icicles after a sunny afternoon are normal. A thick ridge of ice along the gutter line is the start of an ice dam, and it is worth a look at the attic insulation and ventilation.