What are Ice Dams?

Ice Dams

Ice dams occur when water that is running from melting snow and ice, freezes in an area that causes accumulation of this ice and creates a dam effect, causing additional ice build-up and issues such as safety hazards, or leaking roofs.

Where are the most common areas that ice dams occur?

  • Roof edge or eave; the edge of your roof or the eave is the most common area for ice dams to occur. These types of dams can cause major issues in the home or other structure, due to the backing up of water under the roofing material and leaking into the interior of the structure.

The reason that ice dams commonly occur at the edge of the roof, is easily figured out. If the roof has a layer of snow and ice that has accumulated on the roof especially the north or west sides of the structure, thawing of this ice and snow will cause water to drain down the roof. If the temperature is cold enough, the water will not remain liquid all the way down the roof. If the water does not remain liquid all the way down and off the roof and freezes up somewhere on the roof, this ice will cause any water draining to accumulate against this ice. As the water stops flowing and collects, it will freeze and the ice dam starts to build up.

Once the ice dam starts to build up, the water that is still draining off the roof will accumulate against the upper side of the ice dam, and will eventually find its way under the shingles and into the structure. Depending upon the type of roof, the roof flashings, as well as the overhang of the structure, will determine how much water may end up in your living room.

The best method of preventing the accumulation of ice on the edge of the roof, or at the eaves, is to have installed on the last 6 feet of the roof, a full sheet of metal or raised seamed metal roofing. The introduction of a full, impenetrable surface of metal will stop the accumulation of ice and prevent any water from entering the structure. Although the majority of homeowners do not want a full sheet of metal roofing along the perimeter of their roof this is the best method of stopping ice dams and the subsequent negative effects of these dams. The next best trick, to prevent the entrance of water into the home due to ice dams, is the full installation of “ snow and ice shield “ along the edge of the roof, prior to the installation of the shingles. This impenetrable layer of synthetic flashing prevents any water from getting under the roofing and entering the structure. This installation occurs under the actual roofing shingles and is not visible to the observer of the roof itself.


  • Perimeter of the home; Ice dams or ice accumulation is also possible along the perimeter of the home, due to falling water from the roof and eaves. These types of ice dams can cause the water to pool alongside the home and eventually leak into the basement. The presence of any build-up of ice along the homes perimeter can create heavy, thick slabs of ice that once the springtime sun warms and melts the ice, can cause uncontrolled runoff.


  • Driveway entries: Ice dams and ice accumulation, in many instances occurs at the curb-cut of the driveway or entry to the garage. These two areas are normally lower than the surrounding pavement and will cause water to accumulate. If these areas are not free-draining, a build-up of ice can start to accumulate. If this occurs at the curbside of the road, then additional roadside drainage can flow into any type of ice dam that has occurred at the driveway entrance. If this does occur, substantial ice can accumulate in this area and cause difficulties when entering and exiting the driveway.


What are some basic steps to eliminate ice dams and ice accumulation?

  • Proper drainage; One of the principal solutions to ice dam build up is proper drainage. It is essential to keep the water moving and not allow the water to stagnate. Although this appears obvious, the accumulation of water, causing a stoppage of the flow, or a slowing down of the flow of water, will give the water time to cool down enough to freeze. In most cases, flowing water will not freeze in one spot. Although the degree of cold, can cause almost any water to freeze, the moving water will freeze less frequently, and will require a longer period of time to freeze.


  • Unobstructed flow; It is essential that there are no barriers or boundaries that will cause the water to either stop, of slow down, once it has thawed. There should be no broken shingles or uneven surfaces on the roof, driveway or other surfaces, that will have water flowing when the ice melts. Unobstructed flow is essential, and will prevent much of the issues that accumulating ice will cause.


  • Awareness of elevation and exposure; It is important to understand the exposure of any accumulated ice and snow. If the snow and ice has a tendency to pile up, or drift against a portion of the roof, the exposure in terms of north, south, east or west, will cause this accumulated ice and snow to melt at different rates. The southern exposure will normally melt the fastest and the north exposure the least. Due to the tendency to be cooler in the morning, the easterly rising sun will not be as hot as the westerly sunset. Therefore the melting will tend to be greater on the western exposure, as opposed to the east. Once it is determined which elevation the snow and ice have accumulated on, the degree of melting can be estimated.


  • Snow and ice removal; the most important aspect of snow and ice removal is safety of the individual removing the ice and snow. Remember, it is extremely easy to slip on the ice and snow, especially if the removal is required on a sloped roof.   Safety is the ultimate goal. Once the area is secured safely, and you feel that you can remove the ice and snow without incident, then removal should be considered. The less ice and snow, the less drainage and the less possibility of ice accumulating due to pooling of the melted water.

The accumulation of ice and snow can cause substantial problems to a structure. Unfortunately the timing of the issue is normally during a severe storm or extremely cold temperatures. This makes the correction of the problem extremely uncomfortable and difficult. This is why we recommend that during the warm summer months, consideration is given to building up of ice and snow. Making sure that all drainage paths are clear and the eaves of the structure are secure from water building beneath the roofing, is far easier during the warm and sunny summer, than in the midst of a blizzard or extreme cold snap.

Remember, keep the water moving and flowing away from the structure, without any means of accumulating or pooling.