Got ice dams? What to do and how to prevent them

Ice dams, both awe-inspiring and terrifying, can damage homes when snow melts on a warm roof and refreezes at the colder eaves. Find out how to deal with ice dams now and prevent them in the future, which can also save you money on your heating bills.

What to do (and not do) now

One way to prevent ice dams is by removing snow from your roof. While you can try to do it yourself with a snow rake, it may be best to hire a professional snow remover, especially if it takes getting on the roof or using a ladder. Put safety first. If you have an ice dam that is already causing water damage to your interior ceilings and walls, hire a professional ice dam removal service that uses steamers.

A few things you should not do:

• Do not install heating cables as a substitute for air sealing and insulation. They add to your energy costs and do not address the heat loss that causes ice dams.
• Do not remove ice yourself with chippers, chemicals or heat. These can damage shingles, gutters and other building components.
• Do not add powered attic vents to solve ice dams. Natural roof ventilation can help keep roof temperatures uniform, but air sealing and insulation come first.

Warm air leaking into an attic can melt roof snow. Meltwater refreezes at the colder eaves, allowing water to back up beneath the roof covering.

How do ice dams form?

1. Ice dams are primarily caused by the presence of warm air in the attic, combined with snow on the roof and the right weather conditions, with part of the roof above freezing and the eaves below freezing.
2. When heat leaks into the attic, it melts the underside of the snow on the roof. The water then flows down the roof surface until it reaches a cold spot, such as the eaves or soffit, where it forms a frozen dam. The ice buildup can back up under the shingles, damaging the roof and allowing water to leak to the ceilings and walls below.
3. Any penetration into the attic space (around wires, plumbing vents, light fixtures, chimneys, knee walls) is a potential for air leaks. Inadequate insulation, especially near the eaves, is also a contributing factor.

Preventing future ice dams

Ice dams are primarily a heat-loss problem, often caused by a home that is leaking warm air. Roof design, insulation and ventilation also affect the risk.

Due to inadequate air sealing, heat from the home's interior gets into the attic and melts the underside of the snow on the roof. The melted snow water flows down the roof surface until reaching a cold spot, such as the eaves or soffit, where it forms a frozen dam.

Over time, especially with a snow-covered roof in subfreezing temperatures, more ice can build up. Eventually, water starts seeping into the home.

Because a primary cause of ice dams is warm air leaking into the attic, the best prevention is to seal leaks with materials appropriate to each opening, then insulate. For vented attics in climate zones 5 and higher, DOE’s Building America guidance recommends R-60 or greater; the right approach depends on the climate and roof assembly.

Get an energy assessment

An advanced home energy assessment, or audit, is your first step to preventing ice dams and making your home more energy efficient. Ask for an assessment that includes a blower-door test and, where useful, an infrared camera to find attic air leaks and heat loss.

A home energy audit can be arranged through your local utility, a nonprofit energy group or an HVAC professional.

Once problem areas are detected, get bids from at least two licensed contractors to have the work done.

Home Energy Guide & Tips

A comprehensive resource for keeping your home comfortable, safe, durable, and efficient from the Minnesota Department of Commerce.

This article from Clean Energy Resource Teams was republished with permission and updated by Green Builder Media. Videos and other tools are available on the original post here.

Updated content · October 15, 2026