Ice dams form when heat leaking from the house warms the upper roof above 32 degrees while the eave stays below freezing. Snow melts higher up, runs down to the cold edge and refreezes into a ridge. Water then pools behind that ridge and works its way under the shingles.

That is the short answer to what causes ice dams anywhere. Ice dams in Buffalo are more common than in most cities because three local conditions stack up: deep roof snow from Lake Erie, a winter full of thaws, and a housing stock built long before modern insulation.

What Causes Ice Dams: The Three Ingredients

University of Minnesota Extension explains that an ice dam needs snow on the roof, an upper roof surface above freezing and a lower roof surface below freezing, all at the same time. Remove any one of the three and the dam cannot form.

Ingredient	What it means	The Buffalo factor
Snow on the roof	A blanket of snow to melt and feed the dam	Lake effect supplies more than half of the annual snowfall here
A warm upper roof	Heat from the house melts snow from below	Most city homes predate modern attic insulation
A cold roof edge	Meltwater refreezes over the unheated eave	Long stretches below freezing, broken by thaws

Where the Heat Comes From

The sun is rarely the cause. The heat almost always comes from inside the house, and it reaches the roof in two ways.

Air leaks. Warm air rises through gaps around recessed lights, attic hatches, plumbing stacks, bath fans and chimneys. Minnesota Extension calls this the major source of heat loss behind ice dams in many homes.
Thin insulation. Heat also moves straight through the ceiling. The effect is worst where there is little room for insulation, such as sloped ceilings and the knee walls of a finished attic.

Leaky ductwork in the attic and bath or kitchen fans that vent near the roof add to the problem. So does a chimney that is in steady use.

Why Ice Dams in Buffalo Are So Common

Old houses. Census figures reported by WGRZ show that 64 percent of Buffalo homes were built before 1940, the highest share of any large city in the country. Doubles on the West Side, cottages in Kaisertown and the big frame houses of Parkside were built with little or no attic insulation, and many finished third floors have none in the slopes.

Lake effect snow. The National Weather Service climate narrative for Buffalo says more than half of the annual snowfall comes from lake effect, and that areas south of the city get much more of it. Orchard Park, Hamburg and East Aurora roofs carry heavier loads than roofs in Tonawanda or Kenmore.

Thaws. The same narrative describes Western New York winters as cold and snowy but changeable, with frequent thaws and rain. Every thaw sends meltwater toward the eave, and every cold night after it adds to the ridge of ice.

Do Clogged Gutters Cause Ice Dams?

No. A clogged gutter is not what causes ice dams, and a house with no gutters at all can still get one. Gutters do change how bad the dam becomes. When leaves block the trough and the downspouts, meltwater has no path off the roof, so it freezes in place and the ice builds faster and heavier. That weight can also pull hangers loose, which is when gutter repair becomes part of the job.

The National Weather Service guidance on roof ice dams lists cleaning leaves, sticks and other debris from gutters and downspouts as the first step a homeowner can take. Our guide to the best time to clean gutters in Buffalo covers when to schedule that, and downspout cleaning matters as much as the gutter itself.

Hand pulling debris from a clogged gutter, which is not what causes ice dams but makes them worse — Debris holds meltwater in the gutter, where it freezes and adds weight at the eave.

Signs You Have an Ice Dam

A thick band of ice along the eave, often with large icicles hanging from the gutter.
Ice coming out from behind the gutter or through the soffit.
Water stains on a ceiling or on the top of an exterior wall.
Icicles on the siding or around window frames below the roof edge.

Small icicles on a sunny day are normal. A solid shelf of ice that grows over several days is not.

Ice Dam Prevention That Works, in Order

Seal the attic floor. Minnesota Extension puts this first: make the ceiling airtight so warm, moist air cannot reach the attic.
Add insulation. Erie County is in climate zone 5. ENERGY STAR recommends R60 for an uninsulated attic in this zone and R49 where 3 to 4 inches are already in place.
Keep natural ventilation open. Soffit and roof vents help hold the roof at an even temperature. Minnesota Extension does not recommend powered attic fans as an ice dam fix.
Clean gutters and downspouts before winter. This gives meltwater a way off the roof during every thaw.
Rake heavy snow from the ground. The Weather Service suggests a long handled roof rake to keep snow loads down at the eave.
Use heat cables for trouble spots. Valleys and low slopes over unheated porches sometimes freeze even on a well sealed house. Cables manage those spots. They do not fix heat loss.

Steps one and two are the cure. The rest reduce the damage while the cause is still there. If you want the roof edge checked before winter, see our roof and gutter inspection service.

What to Do When an Ice Dam Forms

Stay off the roof. Minnesota Extension warns that anyone on a roof in winter risks injury and can damage the roofing.
Do not chop at the ice. Hammers and shovels break shingles and gutters before they break the dam.
Dry out wet ceilings and walls quickly. Moisture left in place leads to mold.
Call for help if water is coming inside. Our ice dam removal page explains how we handle active leaks.

Frequently Asked Questions

Are icicles always a sign of an ice dam?

No. Icicles form on any roof edge when snow melts in the sun. They point to an ice dam when they hang from a thick ridge of ice at the eave or appear along with stains indoors.

Do gutter guards stop ice dams?

No. Guards keep leaves out, which helps drainage, but they do not change the roof temperature. We do not promise that guards prevent ice dams. See are gutter guards worth it in Buffalo for what they do well.

Will a new roof fix ice dams?

Not by itself. New underlayment can limit leaks, but the dam still forms if heat keeps reaching the roof deck. Fix the attic first.

What is the fastest ice dam prevention step before this winter?

A clean gutter and clear downspouts in November, followed by sealing the largest attic air leaks. Both can be done in one season.

Get the Roof Edge Ready Before the Snow

We clean every gutter by hand, flush every downspout and send photos of the result. Use the free photo quote form or call (716) 415-7160 for gutter cleaning in Buffalo, NY before the first heavy lake effect band.

Written by Mark, owner of Buffalo Gutter Shield. Mark has worked on Buffalo rooflines for more than 8 years.