by George Lewinnek ·
Friday, February 27, 2026
Frequent warming and freezing temperatures can lead to ice dams like this one on Oak Hill Road. (Photo by Lisa Aciukewicz)
The ice dams on roofs in Harvard this winter bring back bad memories for Press reporter Julie Gowel.
A decade ago, water leaking into her house from water dams caused $125,000 of damage. A local contractor, Philip Brown, says that ice dam leaks usually damage the sheet rock or plaster in the ceilings and walls. In Gowel’s home, however, the damage involved not only ceilings and walls in multiple rooms, but also doors and floors. The roof was part of the long catalog of damaged items. It had to be replaced.
This year winter conditions have been unusual once again, and homeowners are seeing ice dams that they haven’t seen for a decade. Many have needed professional help. At least some of the techniques for preventing ice dams have failed this year.
The Press has spoken with a half dozen contractors and homeowners; here’s what we’ve learned. The unusual winter conditions that lead to ice dams are just the right combination of melting, freezing, and leaking. The melting begins with a thick layer of snow on the roof. No matter how well the house is insulated, some heat escapes through the roof. This melts snow, especially when the outside temperature is just below freezing. The water runs down the roof until it reaches the eave. Since the eave is not over the heated part of the house, it is cooler. When it is cool enough, water freezes there. This forms the dam.
The dam holds back a pool of meltwater. As the pool gets deeper, the water backs up under overlapping shingles. The shingles have been nailed so that each nail hole is under one or two higher shingles. When the pool is deep enough to reach a nail, a leak may occur—or may not, depending on the builder’s materials and techniques. Leaks can also occur around vents over bathrooms or around chimneys or along dormers where a wall rises out of a shingled roof. Builders will protect these sites, but deep snow or puddles can overflow the protection.
Roof rakes—poles as long as 20 feet with a hoe-like blade on the end—can be used to scrape snow off the eaves of a first-story roof. This year local hardware and builders’ supply stores have sold out of roof rakes, although a few may still be available online. A hardware store employee in Ayer said that no more roof rakes are expected this season.
To keep weight down, the poles are made of aluminum. Aluminum, most of which is imported, is now in short supply in the U.S. The hardware store employee understood that, with this problem, manufacturers are not making more roof rakes.
Resident Brian Talbot reported that at his home on Bolton Road ice dams formed despite roof raking. At the right temperature, snow from the upper, unraked portion of the roof melted and froze again when it reached the lower, raked, and cooler portion of the roof, even when this was above the eaves.
Residents Dan Kagan and Emily Harris of Old Littleton Road called their roofer for help with their ice dams. The roofer broke through one of the dams with his tools, releasing a cascade as the pool drained. The roofer said that the cascade was “like Niagara Falls.”
Others have gotten help from landscapers and contractors. Ladders and roofs are always dangerous, and even more so when ice is involved. The training and experience of these workers keeps them safer than the rest of us would be. Experience also helps them to avoid damaging the roofs as they cut through the ice.
To manage hard-to-reach places, ice-melting salts can be placed in a discarded nylon stocking. Laid over a dam, this device melts a drainage channel into the dam, so long as one can wait the better part of a day and the temperature is one where ice dams form—with extreme cold, salts do not melt ice. The best salt is calcium chloride. Rock salt (sodium chloride) can shorten the life of asbestos shingles and accelerate corrosion in exposed metal.
For those who have had trouble this winter, the spring would be a time to consider preventive measures for the future. An older house may benefit from newer, closed-cell foam insulation.
Modern construction techniques include placing an air layer between the house and the roof to keep the roof colder. Entrance vents under the eaves and exit vents near the roof’s peak allow continuing ventilation with cool air. Retrofitting this might be considered when the shingles need replacing, but it is expensive. This year the air ventilation could fail when snow and ice covered the exit vents.
Metal roofing material sheds snow at lower angles than asphalt shingles. It might be considered, but ice can still form on metal. Large chunks of ice sliding off the metal create risks to shrubbery, gas tanks, and walkways, so safety must also be considered.
Heating elements can be installed over the eaves to eliminate the kind of ice dam that forms there. Ice dams can still form higher up on the roof, as they did this winter.
Unfortunately, none of these measures completely eliminated ice problems this winter. Those who have had the least trouble quickly called for help when it was needed.
And the reaction to all the problems with snow this winter? Furnace repairman Scott Matheiu, who works out of Leominster, seemed to take the challenges in stride, saying, “But the skiing is great!”