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Five Questions and Answers About Ice Dams on Your Roof

5 Questions and Answers About Ice Dams on Your Roof

By Ardith Stephanson

As if winter weather didn’t create enough problems for homeowners, the hidden dangers of ice dams can be added to the list.

While it’s great to get a break from extremely cold temperatures - the ones that cause issues like frozen water pipes - the jump to warm weather can create its own special headaches.

Like ice dams on the roof of your home.  

If you’ve never heard of ice dams, or you want to make sure that seemingly innocent buildup of ice on your shingles doesn’t turn into a major problem, we’re here to help.   

Here are 5 questions and answers about ice dams on your roof, including how to spot them, how to prevent them, and what to do if you get them.  

1. What Is an Ice Dam?

An ice dam is caused on the roof of a building when a ridge of ice forms that prevents snow and melting snow from draining off the edge or down the eavestroughs. A freeze-thaw-freeze cycle can result in a large buildup of ice over time.

When snow melts and has nowhere to go, the water backs up behind the “dam.” That water can then leak into the home and create a mess of damage to the insulation under the roof, as well as the ceiling, walls below, and even drip to the floors and create major water damage.  

Some of the damage can remain unseen behind the walls and ceilings, leading to further issues like mold, insulation, degradation and more.

2. What Causes an Ice Dam?

The main cause of “damming” is when the surface temperature on the roof of a building fluctuates or is different on different areas of the roof itself. Fast changes in the weather can make the problem worse, like when extreme cold suddenly becomes a sunny day with temperatures above freezing.

For instance, ineffective insulation and or lack of or broken vapor barrier can cause heat to escape from the ceiling onto the roof, causing a non-uniform surface temperature. Add snow to the roof and some sections of it may be cold, while the areas where heat is escaping is warmer.

Snow can even become a layer of insulation on your roof, warming the air in the attic, and then that warm air melts the snow. 

When snow melts, water drips down to areas that are colder, or the melted snow re-freezes when it hits the lower and colder section of the roof. If the melting snow and water doesn’t drain properly, it freezes and builds up to create an ice dam.

The combination of fluctuations in weather temperatures, along with inconsistent temperatures on the roof can create those dams. If the weather continues to fluctuate between bitterly cold and sudden warm spells, the ice dam can actually spread up the roof, with water seeping under the shingles, past the water shield and into your attic. 

Water always finds a place to go, wet always finds dry and in this instance, it finds cracks and openings in the exterior roof covering, even going up under shingles. Water then flows into the attic space, and from there into exterior walls, through the ceiling insulation, or into the rooms below. 

3. How Do You Spot Ice Dams?

Heavy snowfall is the start of an ice dam, but there are some tell-tale signs of an issue. One is a build-up of ice or snow at the eaves, often with icicles hanging down. 

When the melted snow drains down the slope and freezes, some of it drips off to form icicles. The continued thawing and freezing can cause large icicles - also a hazard if they break and fall on someone walking below. 

A bigger issue is when the outside temperature rises above freezing, which causes more melting and results in water leaking into the roof. 

Besides watching for icicles hanging off the eaves, pay close attention to where your roof may form a valley, such as an intersection of two sloping areas. This “valley” can act as a water collector, concentrating all the water from the melting snow of both slopes in the lower end of the valley. If more snow falls, and the temperatures outside go from cold to warm, then it’s an ideal location for an ice dam. 

Even portions of the roof that face different directions can create different issues. As the National Research Council reports: “A roof slope facing south will become bare of snow much more quickly than one facing north, because of melting from heat loss and sun radiation combined. This sometimes can add to the problem of ice formation on north slopes.”

Other places to watch are wide overhangs and extensions of roofs, areas over unheated spaces such as car ports, and other spots where you’ve noticed water or snow gathering. Saskatchewan Government Insurance advises to watch for “uneven melt patterns on your roof, as well as hills or mounds of ice running along the bottom edge of your roof.”

Inside your home, keep an eye out for water stains on the ceilings or walls, or water actually running down the wall, forming pools, or ending up on the floor.

4. How Do You Prevent Ice Dams?

Ice dams tend to be more common in older homes but can happen to any home. Here are a few tips to help lower the risk of ice damming:

Clear snow off the roof: A big buildup of snow increases the chances of a melt-and-freeze cycle that leads to damming. Use a roof rake to clear snow, particularly on the lower part of the roof, or hire a professional to clear the roof after a large snowfall. 

Keep eaves clean: Get in the habit of cleaning your eaves and downspouts each fall and spring. That helps ensure melting snow has somewhere to go. If the eaves are clogged with leaves, you’re asking for trouble. If possible, check and clear eaves during the winter months as well.

Check the attic and roof before winter hits: Make sure your attic has proper insulation as well as circulation. If the air can circulate, it helps prevent heat from being trapped in the attic and warming the roof and the snow on top of the house. Also make sure the chimney, exhaust fans and any other entry points to the attic are properly sealed, to prevent hot air from escaping – which should also help with heating costs. It’s best to have a professional check the attic and do any necessary work for you. 

5. What Happens if You Have an Ice Dam?

Some insurance policies cover the damage caused by an ice dam. Whether or not you have coverage, you need to deal with the issue. And if you have an ice dam, there’s a good chance you have unseen water damage. 

That’s when you need professionals like the team at got mold?™. Water could be hiding behind walls, floors and ceilings. Water inside of your home can become contaminated and cause health concerns due to bacteria. And any kind of water damage can lead to the danger of mold, another serious health hazard.

Contacting the professionals at got mold?™ is the best option if your home suffers from ice damming. 

The Bottom Line

Those warm, sunny winter days that follow cold temperatures feel like a blessing, but can be a danger in disguise to homeowners. Extreme cold weather followed by warm temperatures can create ice dams, which can in turn create water leaks into the house. 

Now that your questions about ice dams have been answered, you can take steps to prevent damming. If it does happen, trust the experts at got mold?™ to provide you with advice and resources to deal with water damage, mold remediation and more. 

Contact us today at 1.888.909.MOLD [6653] to find out more about our services in Saskatchewan, Alberta and Manitoba.

Ardith Stephanson is a freelance writer and journalist who shares some of her own stories at

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