Ice Dams: Facts & Myths
Who, What, Where, When? Who: Roof ice and ice dams result from heat escaping from the attic or space in the roof. This heat builds up and melts snow that is built up on the roof. The water then runs along the cold edge of the roof and forms an ice dam once it freezes. Ventilation, insulation, solar orientation, tree coverage, home architecture, snow cover, and weather conditions are all factors that can cause ice dams on the roof of a home. All houses are different in style, structure and she so it is common to have neighboring homes on two ends of the ice dam spectrum; one may have major leaking, while the other is virtually unaffected. What: An ice dam is a ridge of ice that forms at the edge of a roof which prevents melting snow from draining as it should. Since the water is melting and not draining properly it causes the water to back up behind the ice dam can and leak into the home. This causes damage to walls, floors, ceilings, insulation, and other areas. Where do ice dams happen: Most ice dams occur on the lowest edge of your roof. This does not mean that they cannot occur in other locations on a home. When: Winter is a prime time for ice dams due to snow, freezing temperatures and ice. It is important to be proactive and make changes in your home before winter so that you prevent ice dams from occurring. Facts vs. Myths Fact: Ice dams can occur with virtually no snow on your roof. It takes very little actual moisture to form ice dams. Even a dusting of snow can create a problem. In most cases though, the more snow that is in your roof, the quicker an ice dam will form. Myth: Gutters have something to do with ice dams. Gutters have nothing to do with ice dams. If your home has poor ventilation and little insulation you are bound to get ice dams. However if you have gutters they will fill with ice and provide a foundation for the ice dam above. If you don’t have gutters, the ice dam builds on the cold edge of the roof. Fact: Gutter systems can be damaged by gutter ice. Fresh water ice weighs about 60 pounds per cubic foot and gutters are not designed to tolerate that sort of load. This means that if you allow your gutters to fill with ice, then they are likely to buckle under the load and fall from their position on a house. Myth: When it comes to insulation, the more the better. Improperly insulated homes are just as bad as under insulated homes when it comes to ice dams. Just because you shove a ton of insulation in the wall does not mean it will fix the problem, especially if it is done poorly or wrong. Specifically,insulation done in such a way as to inhibit proper ventilation will cause ice dams and other serious problems. If you don’t address air leakage into the attic or rafter spaces, all the insulation in the world won’t prevent ice dams. Fact:You can’t always see ice dams from the ground. It’s true that you can usually spot a huge ice dam easily. You can also easily see the large icicles hanging from the roof. The hidden ice dams are usually hidden around skylights or in roof pan areas far out of sight. Sometimes ice dams grow up valleys and on top of dormers making it almost impossible to identify from the ground. Myth: Ice dams need to be thick to cause a problem. Ice dams as thin as one inch can cause big problems. A good general rule is that the steeper your roof, the thicker the ice dam has to be to cause problems. On lower pitched roofs even a thin ice dam can hurt. Fact: The leaking caused by ice dams may not show up right away. It would be easy if water stains, leaks and mold appeared immediately upon entering your home but unfortunately this is not the case. Often the water that ice dams push into homes travels around wall and ceiling cavities, trapped by vapor barriers and other materials until it finds the path of least resistance to escape. By the time you see water inside, it’s usually been there for a while.