Does Hot Water Melt Ice Dams? Safer Ways to Clear a Roof Edge

No, do not try to melt ice dams with hot or boiling water. It cools fast, runs down to the cold eave and can refreeze there, it can shock cold shingles and eavestroughs, and it means working on an icy ladder. Safer choices are raking snow off the lower roof from the ground, a calcium chloride sock as a stopgap, or a pro using low-pressure steam.

Can you melt ice dams with hot water? Why it backfires

It looks logical. Ice is the problem and hot water melts ice. In practice, several things go wrong at once.

• It refreezes. Water poured onto a roof edge in freezing weather cools quickly. What does not drain away can freeze again at the cold eave, in the eavestrough or on the ground below.
• It can shock the roof. Cold asphalt shingles, eavestroughs and flashings can be damaged by a sudden change in temperature. Boiling water makes that worse.
• It does not fix the cause. Snow keeps melting from the attic heat below. The dam rebuilds, and the water you added is on the roof as well.
• It makes a hazard below. Runoff freezes on steps, walkways and driveways under the eave, which creates a sheet of ice where people walk.
• The set-up is unsafe. You would be on a ladder on icy ground, next to a slick edge, hauling hot water or a hose up with you.

That is the full answer to the boiling water question too: it is the same problem, only hotter. If water is already coming into the house, the pull to act fast is strong, but hot water is not the fast fix.

Can you break or hammer ice dams?

Not without damage. Natural Resources Canada warns that attacking ice dams with an axe or ice pick will damage the roof surface. Ice at the eave is bonded to the roof covering, so prying or chopping it can tear off shingle granules, lift shingle tabs, dent or bend eavestroughs and scratch metal finishes. You also risk dropping heavy ice on whoever is beneath.

So should you break ice dams? Not as a DIY job. Our post on why DIY ice dam methods often make things worse goes through what homeowners usually try and where it goes wrong. If you cannot reach a dam safely from the ground, leave it for someone with the right equipment.

What you can do yourself from the ground

Can you remove ice dams yourself? Not the ice itself, safely. You can still help from the ground.

1. Rake the snow off the lower roof. A roof rake pulls snow from the first stretch of roof above the eave, so there is less snow to melt and feed the dam. Keep the blade off the shingles, watch for slides, and stay clear of power lines. Our post on when to use a roof rake has the details.
2. Protect the inside. Move belongings away from wet walls, put a container under drips and take photos with the date.
3. Stop the walkway hazard. Keep people and pets away from beneath the eave, where ice and snow can drop.
4. Tell your insurer if water is coming in. The Insurance Bureau of Canada says to contact your insurance provider right away to start a claim.
5. Plan the real fix. Natural Resources Canada says to seal all attic air leaks and insulate thoroughly. That is what stops the melting underneath.

Calcium chloride socks: the DIY ice dam melt, and its limits

The usual DIY melt is a tube of nylon stocking filled with calcium chloride ice melter and laid across the dam, from above the dam down over the eave, so it melts a channel that lets water drain. It is slow, and it does not clear a thick dam.

• Use calcium chloride, not rock salt. Rock salt can be harder on shingles, metal and plants.
• It is still a salt. Runoff can harm plants and finishes below, so use only what you need. Follow the label.
• Placement is the catch. The sock has to sit on the roof. If you cannot place it from safe footing, skip it. A pole is not a plan for a ladder on ice.
• Keep expectations small. It opens a path for trapped water. It will not remove the dam or stop another from forming.

Our post on using de-icing products on Ontario roofs covers the products in more depth.

Low-pressure steam: how ice dams are safely removed

An ice dam steamer, run by a trained operator, works differently from pouring a kettle of hot water. Low-pressure steam cuts channels through the ice and releases it from the roof without hammering or chipping. That lets trapped water drain and avoids the damage that picks and axes do to shingles and eavestroughs.

When to call someone

Call when water is entering the house, when the dam is thick or the roof is steep or high, or when you cannot reach the eave from the ground. The Insurance Bureau of Canada recommends engaging a professional to correct ice dam problems.

D&D Snow Services provides ice dam and ice removal using low-pressure steam, and raking along the lower roof edge to reduce the snow that feeds the dam. It starts with a free written estimate. After the dam is cleared, fix the cause: attic insulation and air sealing first, and heating cable along the problem eaves if drainage still freezes.

Hot water and ice dam questions

Can you remove ice dams yourself?

Not the ice itself, safely. Chipping and hot water risk the roof and a fall. You can rake snow from the lower roof while standing on the ground, protect belongings inside, and call your insurer if water is coming in. An established dam is best removed by a professional with steam equipment.

Should I break ice dams?

No. Natural Resources Canada warns that attacking ice dams with an axe or ice pick damages the roof surface. Chipping can strip shingle granules, lift tabs and bend eavestroughs, and falling ice is a hazard. Low-pressure steam cuts channels without that damage.

Can you melt ice with boiling water on a roof?

It is not advisable. Boiling water cools quickly in freezing air, can refreeze at the eave and below, and can shock cold shingles and gutters. It also means working near an icy edge. A calcium chloride sock or steam from a professional is a safer way.

What is an ice dam steamer?

It is equipment that makes low-pressure steam, used by a trained operator to cut channels through an ice dam and free the ice from the roof. It is different from pouring a kettle of hot water, and it avoids hammering and chipping the roof covering.

Devon Moore, Operations Lead Co-Founder & Operations Lead — D&D Snow Services

Devon Moore is the co-founder and Operations Lead at D&D Snow Services, providing reliable residential and commercial snow removal across Waterloo Region.