Icicles form when ice accumulations form along roof eaves. Ice accumulations are caused by the lower layer of snow that begins to melt when heat seeps from the attic. When those drops of snow move downward and encounter cold air along the eaves of the roof, they form an ice dam. Ice buildup is due to insulation problems in your home.
The heat from your home should not reach the attic; when it does, it causes snow or ice on the roof to melt, water to flow down, and refreeze in gutters, chimneys, skylights, and other areas. In fact, they are an indication of a fairly large problem in the home. You see, as the ice in the gutter gains momentum, it eventually blocks the drain. Basically, it forms an ice dam.
As water continues to flow down the roof, the ice dam blocks this flow, causing the water to basically settle in a rooftop pool. This is an extremely dangerous condition, as water eventually seeps under the shingles, through the roof and into the house. Ice deposits and icicles form when snow melts, goes down the roof, and freezes again near the edge. This only occurs when part of the roof is heated above 32 degrees F, hot enough to melt snow, while the roof edge remains below freezing.
This scenario is usually the result of a warm attic. Attached with clips along the edge of the roof in a zigzag pattern, heated cables help prevent ice deposits that lift the roof tiles and cause leaks. Cutting ice prey with a hammer, chisel, or shovel is bad for the roof and dangerous for you. Small icicles aren't usually a cause for concern, but when you start seeing diameters of two or more inches, you may have bigger problems, such as ice accumulators.
If you can't detect signs of leaks in ice dams, whether on outdoor ceilings or in the attic or on roofs, you may not need to do anything. Most icicles are harmless, but if you pay attention to them and ensure adequate insulation and ventilation, and then proactively manage the snow accumulated on the roof, you can get through another winter without having to deal with the costly and messy problems that can arise when ice dams are left untreated. Removing large amounts of snow from the roof as soon as possible can also be useful to prevent ice accumulators from forming. This is when secondary strategies and ice dam prevention products must be used to prevent damage to ice dams.
If you have large icicles, either in length or diameter, you should be concerned, as they are signs of ice prey. If you're leaking an ice dam and can't remove snow from the roof, the best way to get rid of the ice dam is to hire a roofing company to steam it out. If you're wondering how to fix an ice dam on the roof, here's how you can avoid them completely or remove them if they've already formed. While snowy scenes of icicles in a house look beautiful, even cozy, these ice formations are truly dangerous.
Or, ice dams can constantly form at the foot of roof valleys (the junction where two roofs meet at right angles) because they are filled with wind-blown snow.