Soffit and ridge venting, baffles and attic air leaks: the cure the state's ice dam guidance points to for roofs that melt snow from below.
Fastest: call (833) 751-2102. Or send this and we call you back.
Attic ventilation and insulation keep the roof deck close to outdoor temperature, so snow on top melts evenly or not at all. Heat leaking up from the living space is the usual cause of ice dams. Newton Roofing connects Newton and Middlesex County callers with an independent roofer who checks venting and baffles and says when insulation is a separate trade.
Look at a roof after a snowfall and you can read the attic. Bare patches over the warm part of the house with snow still on the colder overhang mean heat is reaching the underside of the roof deck. The snow melts, runs down the slope and meets the cold edge of the eave, where it freezes into a ridge. Behind that ridge the next melt has nowhere to go but back under the shingles.
The Massachusetts guidance on ice dams describes the cause the same way: heat from the living space and air leaks melt the snow, and the water refreezes at the eaves. It lists the usual culprits as poor insulation, air leaks around recessed lights, ducts and attic hatches, and poor ventilation. Mass Save, the state's efficiency program, offers a home energy assessment and publishes insulation rebates, so it is worth checking current terms before you pay for insulation yourself.
A roofer is not an insulation contractor, and this page says where one trade ends and the other starts. If you are not sure which problem you have, call (833) 751-2102, say what the roof does in winter and what the attic is like, and you will be put through to an independent roofer who serves your town.
Do not step between the joists in an attic or onto drywall, because a foot can go straight through the ceiling below. Do not run a bath or kitchen fan into the attic, and do not block soffit vents with insulation or stuffing; leave work in a tight attic to the roofer.
Ventilation work is priced by the number of vents or baffles, how easy the attic is to reach and whether the roof has to be opened. Insulation and air sealing are priced by a different trade. This site has no sourced local price for either, so there are no dollar figures here.
| Job | Typical range | What it includes |
|---|---|---|
| Clearing blocked soffit vents and fitting baffles | Quoted on site | Priced by the length of eave and attic access |
| Adding ridge or roof-line exhaust vents | Priced by roof length and type | Often combined with a re-roof |
| Rerouting exhaust fan ducts to the outside | Priced by run length and roof or wall exit | Done with new roof or wall flashing |
| Air sealing and insulation | Quoted by the insulation contractor | Ask about the Mass Save assessment and rebate terms |
Nothing on this page is a quote. The roofer and any insulation contractor each set a written price on site before work starts.
A balanced system pulls air in at the soffit and lets it out at the ridge or high on the roof, so the deck stays cold. Too many exhaust vents with too little intake can pull warm house air up through the ceiling, so the two sides need to be planned together.
Insulation pushed into the overhang blocks airflow right where it is needed. Rigid or light plastic baffles hold the insulation back and leave a channel from the soffit up under the deck. It is a small part, but missing baffles are a frequent fault in attics that have been re-insulated over the years.
Sealing the holes into the attic and then adding insulation is the step that stops the heat from reaching the roof. It is usually done by an energy or insulation contractor, often after a home energy assessment, and the roofer has to know what was done so the venting still works.
Call any hour and explain what is going on. You get a clear price before any work starts.
Warm air that leaks into the attic heats the roof deck from below, so snow melts above the heated part of the house. The meltwater runs down to the unheated overhang, refreezes and builds a ridge of ice. Water then backs up behind that ridge and works under the shingles.
This is why salting or chipping at the ice is a stopgap and not a cure. The heat is still there, and the next snowfall will do the same thing. Where a house is well sealed and well vented, the whole roof stays about the temperature of the air outside and the snow sits or melts at the same rate everywhere.
Our ice dam prevention page describes the on-the-roof side of the problem, and the ice dams in Newton guide goes through the causes in order.
Under 780 CMR R905.1.2, where there is a history of ice forming along eaves, asphalt shingle, slate, wood shingle and shake roofs need an ice barrier. That means two cemented layers of underlayment or a self-adhering polymer-modified bitumen sheet, from the eave to at least 24 inches inside the exterior wall line.
That is a barrier against water that gets past the ice, not a cure for the ice. It works with ventilation and insulation, not in place of them. Which areas count as having a history of ice is designated in the code's table, so ask the Building Department what applies to your address.
Sometimes it helps, but ventilation does not seal leaks from below. Warm air that is pouring through a hatch or around lights keeps feeding the roof deck no matter how many vents are cut. The state's guidance puts air sealing and insulation alongside ventilation, and a house usually needs a mix of the three.
Adding vents to a roof that has a bad ceiling is a little like opening a window while the heat is still on. If the energy assessment shows large gaps, the sealing comes first and then the vents are set to move the right amount of air.
Ask the roofer to be specific about which vents are being added and why, and where intake air will come from. A line item that says only vents added is not enough.
Look for signs rather than counting vents: frost on the underside of the deck in winter, damp or stained wood and insulation, uneven snow melt and ice at the eaves. A roofer can measure the vent openings against the attic floor area, but the winter and summer symptoms tell the story first.
In a snowy climate the winter symptoms are the ones to watch: moisture on the deck, damp insulation and ice at the eaves.
The roofer looks at where snow melts first, where ice forms and whether intake vents at the eaves and exhaust vents near the ridge exist, since air has to enter low and leave high.
Inside, the roofer checks the underside of the deck for frost or stains, whether insulation blocks the soffit openings and which fans, ducts, hatches and lights are leaking warm air into the space.
Baffles are fitted at the eaves to hold insulation back and keep a channel open, soffit vents are cleared or added, and exhaust ductwork is carried to the outdoors. This is roof-side work.
Sealing the gaps in the ceiling below and adding insulation is air sealing and insulation work. The roofer will usually tell you when a Mass Save assessment or an insulation contractor is the next step.
Where eaves have had ice damage, the roofer checks the underlayment and whether an ice barrier, a waterproof layer under the shingles at the edge, is there. If not, it may be part of the next re-roof.
Arlington's housing is among the older stock in the area, with one source putting about 47 percent of homes as built before 1940. Older houses often mean original framing, chimneys and eaves where heat loss can feed ice dams, and an attic full of past patches. Look for old insulation pushed hard into the overhang.
Framingham's 1950s Campanelli ranch houses had one story and a low-pitched roof. Low-pitched roofs shed snow slowly and are more prone to leaks at shingle laps and ice-dam backup, so underlayment, an ice barrier and a well-ventilated attic matter more than on steeper roofs. In Dedham, where the median home dates to the 1950s, older eaves may lack the ice barrier the current code asks for where ice dams are a known risk.
Needham's mid-century Capes and ranches carry older asphalt roofs that are often at or past the usual lifespan of 20 to 30 years, and ventilation is among the things worth checking when one is replaced. See the Framingham and Dedham pages for more on those housing types.
Not sure if you're covered? Check your ZIP code.
Ice removal, leak repair and the attic fixes that stop ridges of ice forming at Newton eaves.
A roofer's written look at decking, flashing, ventilation and remaining life, for buyers of older houses and owners weighing repair against replacement.
Re-hanging, replacing and clearing gutters that snow, ice and leaves load down on wooded Newton-area lots.
Full tear-offs and re-roofs for Newton houses, with the building permit and the ice barrier handled as part of the scope.
Ice dams form when heat from the living space and air leaks melts snow on the warm part of the roof, and the water refreezes at the cold eaves.
Often both. A roofer fixes venting, baffles, flashing and the ice-damaged eaves. An insulation or energy contractor seals air leaks and adds insulation. Start with whichever problem you can see. The roofer should tell you when the heat loss is the bigger issue.
Mass Save offers a home energy assessment and lists insulation rebates and air sealing, according to the state's ice dam material. It looks at where your house leaks heat, which is the cause of ice dams. Check Mass Save directly for what is offered now and what it requires.
You can, but pushing batts into the eaves is the most common way homeowners block their own venting. If you do it, keep baffles in place and the soffit openings clear, and seal the ceiling gaps before adding material. Many people find it easier to let a contractor handle the sealing.
A properly flashed vent should not. Poor installation, missing end caps or wind-driven snow can let water in. If a ridge vent was added and stains followed, tell the roofer, who can check how it was cut and fastened.
Minor repairs are usually described as not needing a Newton building permit, and a full replacement does need one. Vent changes during a re-roof fall under that permit. For a stand-alone job, ask the Building Department rather than assuming.
Damp air from the house is probably reaching the cold side of the roof, or a fan is exhausting into the attic. Moisture then collects on the deck and on insulation. A roofer can check for stained wood and ductwork. Do not seal or paint over the stains until the cause is found.