Ice dam damage: what it does to a house and how to repair it

Repairing ice dam damage is two jobs. One is fixing what the water ruined: the stained ceiling, the soaked insulation, the rotted trim at the eaves. The other is fixing why the dam formed, which is almost always heat leaking into the attic. Patch the ceiling and leave the attic alone, and the stain tends to come back the next hard winter. In Saratoga County, where snow can sit on a roof for weeks while the temperature bounces above and below freezing, ice dams are one of the most common ways water gets into a house in winter.

How an ice dam forms

An ice dam is a ridge of ice along the bottom edge of the roof. The upper roof, over the heated part of the house, gets warm enough to melt the snow on it. The eaves hang out past the walls and stay below freezing. Meltwater runs down under the snow, hits the cold eave and freezes. The ridge grows and water pools behind it. Shingles are made to shed water running downhill. They're not made to hold back a puddle, so the water works its way up under them and into the house.

The heat that melts the snow comes from your living space. Warm air slips into the attic through gaps around the attic hatch, recessed lights, plumbing vent pipes and the top plates of the walls. Thin or patchy insulation lets more heat through the ceiling. Poor attic ventilation keeps that warmth pressed against the underside of the roof deck. Older houses get it worst, along with houses that have finished attic rooms or low-slope roof sections.

Long icicles and gutters packed with ice are usually the first thing you'll see.

Where the water ends up

Water from an ice dam doesn't always come out where it went in. The obvious damage is stains on top-floor ceilings, often near the outside walls, and paint that peels, bubbles or cracks on ceilings and high on walls. Old plaster cracks and sags, because soaked plaster loses its grip on the lath.

Up in the attic, wet insulation packs down and loses much of its insulating value. Water can run down inside the walls and show up as stains around windows or at the baseboard. At the eaves, roof sheathing, fascia and soffits rot, and the weight of the ice can tear gutters loose or bend them.

A lot of this stays hidden. Insulation and framing can sit wet for weeks before a stain shows, and wet material in a closed wall or ceiling can grow mold.

During a leak

If water is coming through the ceiling during a thaw, move furniture and belongings out of the way and catch the drips with buckets and towels.

Water near a light fixture, outlet or ceiling fan is an electrical problem first. Shut that circuit off at the panel and have an electrician check it before you use it again.

A ceiling that's bulging may be holding a lot of water. Keep everyone out from under it and call a professional. Don't poke a big bulge yourself.

From the ground, you can use a roof rake to pull snow off the bottom few feet of the roof, which cuts down the meltwater feeding the dam. Don't climb onto an icy roof, and don't go at the ice with a hammer, an axe or a shovel. That tears up shingles and it's how people fall. Roofers who do this work cut channels through ice dams with low-pressure steam.

Take photos as it happens. They help with an insurance claim, and later with tracing where the water came in.

Fix it in this order

Start in the attic, if you can get into it, during the leak or right after. Water stains on the underside of the sheathing, wet insulation, and frost on the tips of the roofing nails all point to where heat and moisture are collecting.

Then fix the attic. This is the part that stops a repeat. It means air sealing the gaps between the living space and the attic, adding insulation so it's an even depth all the way across, and making sure the soffit and ridge vents work together so cold outside air runs under the roof deck. Insulation and air sealing are often done by an insulation contractor, and a home energy assessment can show where the heat is getting out.

Next, the roof edge. Rotted sheathing, fascia and soffits at the eaves get replaced. When a roof is replaced, an ice barrier membrane goes down along the eaves under the shingles to help keep backed-up water out. The New York State Residential Code addresses ice barriers at the eaves; your building department can confirm what applies to your roof. Our post on soffit and fascia repair covers the trim end of this.

Inside comes last, and only once everything is dry. Paint over a damp ceiling and it peels, and the stain bleeds back through. Wet insulation in walls or ceilings generally has to come out. A stain on otherwise sound drywall can often be sealed with a stain-blocking primer and painted. Sagging plaster may need to be reattached or replaced. Mold on framing, insulation or drywall should be looked at and handled by a mold professional.

Old ceilings after a leak

A lot of older Saratoga County houses have plaster ceilings, and some got a textured or popcorn finish added later. Have a textured ceiling tested for asbestos before anyone disturbs it. In a house built before 1978, test painted plaster for lead before sanding or scraping.

A cracked plaster ceiling doesn't always have to come down. Depending on its shape, it can be repaired, skim-coated, or covered. One badly cracked ceiling shown on our site got tin-look tiles, which hide the damage and look right in an old house. Our guide to restoring an old house in Saratoga Springs covers how we decide between repairing original finishes and replacing them.

Water running down the outside wall can soak the upper-floor window trim too. If those sills are soft come spring, see our post on window sill rot repair.

Heading off the next one

Clean the gutters in late fall so meltwater has somewhere to go; our fall home maintenance checklist puts it on the calendar. Rake the lower roof from the ground after big storms. Seal and insulate the attic, which is the fix that lasts. And look for new stains every spring as part of a spring home inspection.

Heat cables along the eaves can help in a trouble spot, but they treat the symptom and leave the cause in place. They need to be put in by a qualified person, following the manufacturer's instructions.

Frequently asked questions

Do gutters cause ice dams?

No. Ice dams come from heat escaping through the roof, and they form on roofs with no gutters at all. A clogged gutter can make it worse by holding ice at the edge, but cleaning gutters by itself won't stop them.

Can I paint over an ice dam stain on the ceiling?

Only after the ceiling and everything above it are fully dry and the cause is fixed. Prime with a stain-blocking primer first or the stain will bleed through regular paint.

Does homeowners insurance cover ice dam damage?

Policies vary. Many cover sudden water damage inside the house but may treat the cause differently. Call your insurer, and photograph the damage before you clean up.

Once the attic's sorted, we repair the water-damaged ceilings, trim, soffits and fascia, keeping original finishes where we can. That falls under our restoration and built-ins work.