Ice Dams and Roof Snow in New Hampshire: Causes and Fixes
Ice dams are the ridge of ice you get along the bottom edge of a roof, holding back melting snow. Ask around New Hampshire in February and you'll hear about them constantly, older houses most of all. Heat is what causes them. Warm house air gets into the attic, and the snow up top melts. The water runs down to the cold eave. There it freezes. Clearing snow helps in the short term. Stop losing the heat, though, and next winter you don't get a dam in the first place.
How an ice dam forms
Say there's a foot of snow up there. Over the heated rooms, the roof runs warmer; past the outside wall, where it hangs out over nothing, it's cold. Let heat from the house leak into the attic and the roof deck warms from underneath. The snow on top starts melting. That can happen on a day the thermometer never gets anywhere near freezing.
Under the snow, the meltwater slides downhill. Then it hits the overhang. No house below, just cold air, so it freezes. Next day, a bit more. Then more. Eventually water pools behind it with nowhere to go. Shingles are designed to shed water running downhill, not to hold standing water, so it backs up under them and finds its way into the house.
Icicles on their own are not proof of an ice dam, but a row of heavy icicles along the gutters is often the first visible sign. So is a roof where the snow has melted in patches over the living space while a thick band of ice sits along the edge. Plenty of older, thinly insulated houses have both going at once.
Signs of ice dam damage inside the house
Where the roof meets the outside walls, that's usually where the water turns up first. A brown or yellow stain on the ceiling near an exterior wall. Paint peeling up high. Drywall gone soft, or bubbled. Or it's just a drip at the top of a window, or a wet patch in the carpet under one.
Go look at the tops of the upstairs windows. Open the closets on outside walls too; nobody ever checks those. Got a finished attic room, or sloped ceilings upstairs? Watch the knee walls and the slope. Roof, insulation and bedroom are all jammed together there.
Insulation that's wet doesn't insulate. Drywall that stays damp can grow mold. So if there's a leak, sort out the water on the roof first. Then open the ceiling or wall and let it dry. Paint over a stain before the source is fixed and you've only hidden the next one. Same stain, same spot, every winter? That's your attic telling you where the heat's getting out.
Roof rake from the ground, or someone on the roof
A roof rake is a long aluminum pole with a blade on the end. After each storm you stand in the yard and drag the snow off the bottom few feet of roof. With that edge clear, the meltwater has less to freeze on, and the eaves carry less weight. Of all the things you can do yourself, it's the safest. Your feet never leave the ground.
Pull straight down. Not sideways. Don't dig the blade hard into the shingles, and don't let it drag across them either. Watch for power lines and service drops near the roof edge, and stand well clear of where the snow will land, especially off a steep metal roof. Clear the snow off vents and away from the base of the house when you are done, and never climb a ladder onto a snowy roof to finish the job.
When the dam is already built and water is coming in, or the roof is too high or steep to reach, it is a job for someone with the right gear. Go at it with a hatchet or a shovel and you'll crack shingles and rip the gutters down. Most of the time the dam comes off with low-pressure steam instead. It melts channels through the ice. Nothing gets chipped.
The long-term fix is in the attic
The dam's really a symptom. The disease is heat getting into the attic. The real fix usually has three parts. Air sealing goes first, then insulation, then ventilation, in that order. We've all heard of the house that "had the attic done" and still dams; usually one step got skipped, or they went out of order.
Air sealing: you close up the gaps warm air uses to get from the house into the attic. Around light fixtures, mostly. Holes drilled for the plumbing and wiring. Chimney chases. The attic hatch. Older New Hampshire houses tend to have plenty of these. Insulation then slows the heat that still conducts through the ceiling. Ventilation, with air coming in at the soffits and out near the ridge, keeps the underside of the roof cold enough that snow melts evenly instead of at the edges.
NHSaves, the state's utility-sponsored efficiency program, offers home energy assessments and incentives for weatherization work like air sealing and insulation. ENERGY STAR publishes plain guidance on sealing and insulating an attic. Read both before paying for anything on the roof. Brand-new shingles over a leaky attic will dam right along with the old ones.
When to call
Water coming in? Call. Snow too high or too heavy to reach safely from the ground? Call. The same ceiling stain showing up winter after winter is the third reason. The first one is urgent. The last is a sign the attic needs attention once the season ends and the roof is dry enough to work on.
After a leak, take photos of the stains and the ice from the ground before anything is cleared. They help later, both for working out where the water came in and for any conversation with your home insurer. Note the date and which rooms were affected while it is fresh.
Crimson Maple Construction handles roof snow removal, ice dam removal and roofing around Manchester and southern New Hampshire. Call (603) 722-3344, or message us a photo of the roof edge — we’ll get you a number.
Questions people actually ask
- What causes ice dams on a New Hampshire roof?
Heat escaping from the house into the attic warms the upper roof and melts the snow on it. The meltwater runs down to the overhang, which sits over cold outside air, and refreezes. Over days the ice builds into a ridge that traps more water behind it. That water can back up under the shingles and leak into ceilings and walls.
- Is a roof rake enough to prevent ice dams?
A roof rake helps. Pulling snow off the lower few feet of the roof from the ground after each storm leaves less snow to melt and refreeze at the eave. What it won't touch is the cause: heat leaking into the attic. If your house dams every winter, think of the rake as buying time until the air sealing, insulation and ventilation get done.
- Should I chip the ice off my roof myself?
Please don't. A hammer, hatchet or shovel is about the quickest way there is to crack shingles and yank a gutter off, and an icy roof is a dangerous place to stand. Keep to the ground and use a roof rake on the snow. Dam already built, water already coming in? Have it taken off by somebody with the equipment. That usually means low-pressure steam.
- How do I know if an ice dam leaked into my house?
Stains on the ceiling close to an outside wall are the big tell. Also paint peeling or bubbling high up, drywall that's damp or soft, and water marks over the upstairs windows. Don't forget closets on outside walls, or sloped ceilings upstairs. Once insulation above a stain gets wet it quits working. So when the roof's handled, expect to open the ceiling and dry it out.
Before hiring anyone for this kind of work, it is worth reading what New Hampshire does and does not license and how a written quote should read. About Crimson Maple Construction covers who would be doing the work.
Where to check this yourself
The work this guide is about
- Ice dam removalIce dam removal in Manchester, NH: why dams form at the eaves, steam vs chipping, what to ask whoever clears them, and the attic fix that stops them returning.
- Roof snow removalRoof snow removal in Manchester, NH: when snow load becomes a problem, warning signs inside the house, roof rakes vs shoveling, and protecting the shingles.
- RoofingRoofing in Manchester, NH: shingle repair or replacement, tear-off vs overlay, ice barrier at the eaves, flashing and ventilation, and what to send for a quote.
The other guides
- Hiring a Contractor in New Hampshire: What to Check Before You SignNH doesn't license general contractors. So "are you licensed?" gets you nowhere. Ask these four things instead.
- Manchester NH Building Permits: What Homeowners Should KnowManchester's Building Division, decks, electrical, who pulls the permit. And the one phone call that settles it.
- Lead Paint in Older New Hampshire Homes: Renovating SafelyBuilt before 1978? Then sanding, scraping and old windows come with federal rules. Here's what to ask first.
- LVP, Tile or Hardwood: Choosing Floors for a New Hampshire HomeBasement, bathroom, mudroom. Slush and salt on the way in. Which floor survives where, and why the subfloor matters.
- Drywall Repair or Replace: How to Decide in an Older HomePatch it or re-sheet it? Plus what's different when the wall turns out to be 1900s plaster and lath.
Manchester, NH
Tell us what the house needs
Call and describe the job. If it is on the service list, ask how it would go. Foundation work and concrete pads are not on it.