Lake-effect snow, roof leaks and ice dams in Buffalo

Why does heavy snow lead to roof leaks?

Heavy snow adds weight and holds moisture against the roof. When the temperature rises and then falls, meltwater runs to the eave and refreezes, and the water behind the ice finds a way under the shingles.

A deep snowpack holds meltwater against the shingles. In the daytime the melt runs down the roof, and at night it freezes at the eave, where the roof is coldest. The frozen ridge of ice, called an ice dam, holds the water behind it, and the water has to find another way out.

The water often travels under the shingles and along the rafters before it drips through a ceiling. The leak can be several feet from the stain, which is why the attic should be read before the ceiling is opened.

How big was the snow record in Buffalo?

The National Weather Service Buffalo office records 16.1 inches of snow in one day in November 2022, which broke the record of 7.6 inches set in 2014. The December 1979 storm dropped 20.1 inches at the Buffalo Airport over about 24 hours.

The November 2022 storm is the most recent large single-day record in the sources. The office reports that it broke the 7.6-inch single-day record from 2014, which means the city's roofs were loaded more than the previous record had prepared them for.

The December 1979 event is described by the same office as the second-greatest 24-hour snowfall on record. Reports of the November 2022 total for Orchard Park differ, so this guide does not give a figure for that town.

How does an ice dam differ from condensation?

An ice dam leak shows as a stain or wet insulation near the eaves, often after a warm spell. Condensation shows as frost or dampness across the underside of the roof sheathing and a general musty feel.

An ice dam leak is usually at the outer edge of the house, and the stain on the ceiling runs toward the eave. The attic insulation there is wet or compressed. Condensation is more even across the attic and shows frost on the sheathing when it is cold outside.

Both can be present in one house, and each needs a different repair. A roofer addresses the ice dam and the roof edge, and an attic ventilation contractor addresses the condensation. A restoration crew reads the attic and the ceiling together and records what it finds.

What do you check after a heavy snow?

Check the top-floor ceilings and walls for stains and bubbling, the gutters and eaves for ice, and the attic if it is safe to enter. Note the date and the weather when a stain first appears.

Look along the outside walls and in the corners of the top floor, since those are where water from the eave usually shows first. A stain that grows, a bubble in the paint or a new crack in the plaster is a reason to call.

Look at the gutters and downspouts for ice that is blocking the flow, and at the eave for a dam. If snow is piling at the eave, clear the lower part of the roof from the ground with a roof rake, and keep the path to the house clear of ice.

• Look for stains and bubbling on top-floor ceilings and walls
• Check the gutters, downspouts and eaves for ice
• Enter the attic only if it is safe, and look for wet insulation
• Note the date and the weather when a stain first appears
• Do not climb onto an icy roof

Why should the framing be dried before the ceiling is closed?

Wet rafters, joists and sheathing hold moisture that can rot the wood or support mold if it is sealed in. Drying the framing to its readings before the ceiling is closed is the step that prevents the problem from returning.

Wood holds water in its cross-grain and joints. When it is covered by new drywall or insulation before it is dry, the moisture stays inside. The crew measures the moisture in each member near the leak and along the path the water took, and it dries the wood until the readings show a steady dry level.

Plaster and drywall below the framing are opened where they cannot dry in place. The openings are recorded, so the roofer and the owner know where the leak was and what was removed.

Who repairs the roof, and who dries the damage?

A roofer repairs the roof, the flashing and the shingles, and a restoration crew dries the water damage inside. The two jobs are separate, and each one should be done in order, with the note from the drying passed to the roofer.

A roofer checks the edge, the valleys and the flashing, and repairs the leak point. Some roofers also advise on ventilation and insulation at the eave, which can reduce the risk of ice dams. A drying crew does not repair the roof and says so when the source is outside its scope.

The crew's note gives the roofer the leak point, the readings and the openings made. That saves time on the roof and makes sure the repair starts from the right place.

What is the risk to a person on the roof or under a ceiling?

A roof covered in snow or ice is dangerous, and a falling sheet of ice can injure someone below. A ceiling that sags or bulges can fall without warning, so keep out from under it.

Climbing onto a snow-covered roof to clear it causes more injuries than most leaks. Use a roof rake from the ground, and keep the path to the door clear of ice. Ice falling from the roof edge can injure people below, so the area under the eave should be kept clear.

A ceiling that is sagging, bulging or cracking along a seam should be left alone until a crew has checked it. The crew can support or remove the sag where it is safe, and it can recommend a structural check if the sag points to a problem with the framing.

What does a leak like this cost to fix?

The cost depends on the number of rooms reached, the amount of framing and insulation that is wet, and the roof repair itself. The price for drying is explained and approved on site before any equipment is set up, and no figure is given in this guide.

A stain in one corner of one room is a smaller job than water that has run along the rafters into several rooms. The number of openings, the insulation removed and the finish that has to be restored all add to the drying scope.

The roof repair is priced by the roofer, and the finish repair by the people who do that work. The owner should ask for each price separately, so the work can be compared without confusion.

How can you reduce the risk of the next ice dam?

The main steps are a sound roof edge, sealed attic openings and attic ventilation that keeps the roof cold and even. A roofer or a building contractor can advise on what suits a particular roof.

Heat leaking from a warm attic melts the snow on the roof, and the melt refreezes at the cold eave. Sealing the attic floor against warm air and improving ventilation can reduce that cycle. Those are building measures for a qualified contractor, and this guide does not recommend a product.

After a repair, keep the gutters and downspouts clear and check the roof edge after each heavy snow. Clear the lower part of the roof with a roof rake from the ground when snow is piling up. A record of when a stain appeared and what the weather was like helps the roofer decide what to change.