Home Sense

What to Know About Ice Dams

If you’re no stranger to snow, then an ice dam on your roof is a dangerous seasonal possibility.

An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow from draining off the roof. From gutter damage to unintended injuries, an ice dam can spell disaster. Fortunately, ice dams can be easily mitigated if you take steps to prevent them from forming or if you remove them as soon as they start to form.

How do ice dams form?

If you’ve ever been tasked with removing an ice dam from your home, you might have wondered how the ice dam formed in the first place.

To form, the dam requires the perfect temperature conditions and a bed of snow. Temperatures at the snow's highest point must reach above freezing (32 F), while areas at the base of the snow must be below freezing.

If these conditions exist, the snow in higher area — above 32 F — will begin to melt and run downhill. When it does, this water will come into contact with the colder snow and turn to ice. This ice then blocks the way for additional melting moisture to escape, making the dam grow larger and larger.

As the dam keeps growing, it will only continue to add ice in areas that are below freezing. Once the water backs up into the region where freezing temperatures are no longer present, that water will search for other places to escape — including into a home.

Where do ice dams most commonly form?

Ice dams require very specific conditions to form successfully. Yet those conditions are usually more common than you may think.

The slanted roofs on many homes are ideal staging areas for ice dams, particularly if the lower half of the roof is shaded by another section of the roof or the home itself.

Temperature conditions inside the home can play a part in ice dam formation as well. In many cases, the warm air rising to the ceiling inside the home also warms the roof. This heat keeps the higher portion of the roof warm. Meanwhile the lower portion—which is designed to hang away from the house—stays cool. This creates the ideal conditions for an ice dam to form.

Areas of your house that are shaded tend to get more ice dams since the sun isn’t present to melt the damage.

What makes ice dams dangerous?

Ice dams are formed by winter moisture trapped in a specific area, such as a crux in the home's roof. The potential for damage exists wherever this water collects. An ice dam can also spread water and ice on the ground beneath it, creating hazardous walking conditions along the home's exterior. Those beautiful icicles pose another very real danger to anyone walking beneath them.

Most often, however, the greatest danger posed by ice dams is to the home's gutter system. While any of these potential hazards is reason enough to remove ice dams from your home, the danger posed by ice dams to the home’s interior is usually the most detrimental and expensive.

When an ice dam forms, it applies pressure on the structure and channels water from the home’s exterior through the building’s envelope (the term used to describe the home’s roof, exterior walls and floor). Once water has entered this space, it becomes more difficult to detect and remove.

Damage caused by this stagnant water can include:

  • Rotting in the home’s roof decking, exterior and/or interior walls, and rafters.
  • Mold growth, which can affect the health of people in your home.
  • Peeling paint caused by the presence of water in the wall cavity. This damage can actually appear after the ice dam has disappeared if the water remains and festers in the wall.
  • Reduction in the effectiveness of the home's insulation.Wet insulation performs poorly compared to dry insulation; if the insulation becomes wet enough, it may never dry out correctly.

While the icicles may be beautiful, they’re also a warning sign of problems that lie beneath.

How do you prevent an ice dam?

Preventing ice dams from forming should be a goal of any homeowner in a cold-weather climate.  Fortunately, there are quite a few things you can do when it comes to preventing ice dams from forming on your home.

Control your home’s temperature

Ice dams require certain temperature conditions in order to form, so it's to your benefit to prevent them from occurring. For starters, avoid heating your roof or attic. The heat emitted from a roof or attic can melt the snow on the roof, and that can help form an ice dam. (Eliminating this heat waste is also a helpful energy saver that can lower your utility bills.)

To prevent your home’s heat from leaking through the roof, inspect the attic's insulation. The same insulation that blocks cold air from coming into the home can stop warm air from reaching the roof. Your attic’s insulation should be 12 inches thick, though 15 to 20 inches is recommended if you live in an area with especially harsh winters.

This is also a good time to check your attic’s ventilation capabilities. They should let cold air enter the attic and let any warm air that enters escape — preferably rapidly. When warm air lingers in the attic, it can heat the roof and lead to the formation of ice dams.

Prevent extra, unnecessary sources of heat

Properly insulating your attic is the first and most important step to keeping your roof cool and preventing ice dams. Yet there are other things you can do when it comes to preventing ice dams from forming.

For starters, contact an HVAC professional and ask him or her to inspect your system. You should schedule this check-up every fall to make sure your furnace is ready for the winter and to ensure the system is ventilating properly. Furnace or bathroom vents that accidentally leak heat into the attic will only make ice-dam formation more likely.

You can also use this time to inspect any other openings to your attic, such as pipes or cable holes. Take the opportunity to apply caulk or sealant to these areas if necessary. This will prevent additional warm air from seeping into your attic, which can go a long way toward keeping your roof safe and dry for another winter season.

Even the best preparation can sometimes lead to an ice dam

You’ve done your homeowner due diligence and tried your best to take the necessary steps to prevent ice dams. However, when you look at your roof, you see icicles, the ground is slick beneath your feet and you can spot snow, ice and debris above your head. The telltale signs are all there: You have an ice dam. (Yikes!)

What should you do about it?

The short answer, of course, is to remove the ice dam. An ice dam shouldn’t be ignored.Before you remove an ice dam, you first need to decide whether you will tackle the task yourself or hire a professional. Here’s what to consider when it comes to both options.

Getting rid of an ice dam yourself

It may seem counterintuitive, but the best way to remove an ice dam is to first focus on the snow. Ice dams require specific conditions to form, and the snow on your roof supports these conditions by acting as an insulator.

Start the ice-dam-removal process by using a roof rake to pull snow from your roof to the ground. Use a telescopic roof rake and try to remove the three to four feet of snow closest to the edge of your roof.

Once you've removed the snow, you’ll see the ice formation underneath. Use a ladder to reach this area and apply an ice melt product like calcium chloride. If you don't have a ladder or you're not interested in climbing one, you can also use throwable ice-melt solutions, such as ice melting pucks. These products, which are the size of small plates, are specifically designed to be thrown up on the roof to melt ice in hard-to-reach places.

Applying an ice-melt product is the safest, most efficient way to remove an ice dam from your home. Under no circumstances should you ever try to melt the ice with fire or chip away at the ice with an axe, pick, screwdriver or similar object. Doing so will only expose you to injury and your home to damage.

Hiring a professional to remove your ice dam

If you’d feel better leaving your ice dam removal project to the experts, head online to hire a contractor in your area. Look for one who will remove the ice dam using low-pressure steam as opposed to high-pressure washing, which can damage your roof. 

Low-pressure steam may be expensive. But if you’re okay with the higher cost, hiring a professional will spare you from having to tackle one of winter’s most notorious weather issues.  Average costs for professional roof snow removal and ice dam removal could be anywhere from $50/hour or $300-$500 per job*. Before any ice dams are removed, 3-4 feet of snow needs to be cleared away from the gutters or the ice dam will return almost immediately. 

Another way to protect your home during winter is by having the right homeowners insurance. Find out which coverages you need by talking to an Erie Insurance agent in your community.

*Costs for ice dam removal services are subjective and will vary based on regional pricing, roofing systems and complexity. Erie Insurance does not endorse specific contractors and it is ultimately the decision of the individual on who to hire for a specific job.


The icicles hanging from your roof give your home that iconic winter appearance. Their appearance, however, means something else if you recognize them for what they are: a tell-tale sign of an ice dam. If you have an ice dam on your property, you need to remove it as quickly and safely as possible. /blog/what-to-know-about-ice-dams Erie Insurance