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. When you see icicles forming in gutters and eaves, it's an indication that ice prey is accumulating on the roof. These ice deposits can cause damage to the interior and exterior of your home, and should be fixed as soon as possible. In addition, if an ice dam breaks, it can tear off shingles and gutters with it, damaging anything it falls on.
When the roof coating gets wet, it can form mold and rot, causing more damage to the roof. Icicles form in gutters when excess water is not allowed to flow freely through the gutters. In winter, the heat inside the house usually keeps the roof warm, causing the snow that has accumulated there to melt. As the snow melts, the water flows into a cold gutter, accumulates there and spills down the sides, forming icicles.
Ideally, this running water would follow the course of the gutter and go down the rain pipe. But if the gutters are clogged with obstructions, such as leaves or soil, the extra water tends to flow down the sides, causing icicles to form at temperatures below zero. When winter comes and snow accumulates on the roof of your house, it will melt and fall into the gutters. As they become depleted, it can freeze again and therefore produce icicles.
These icicles are formed due to several factors. If you live in a northern state, cold winters and heavy snow are the norm. When the weather clears and the sun rises or when the heat inside your house moves to the outside, the snow on the roof will melt, at least partially. As the melted snow begins to drip, contact with sub-zero air freezes it again, in the form of tiny frozen droplets.
New droplets run along the sides of these forming icicles and then freeze as they move downward, causing the icicles to increase in size, sometimes dramatically. The record for the longest icicle is in dispute, but claims range from 28 to 45 feet. The weight of ice trapped in the gutter can damage the gutter or tear it completely off the side of the house. Newer homes that are well insulated, or older ones, only receive ice when the outside temperature is close to freezing, for example, between 28 and 32 degrees.
While snowy scenes of icicles in a house look beautiful, even cozy, these ice formations are truly dangerous. My hypothesis about this ice in the garage is also the reason why I think well-insulated houses had problems in this “storm”. Those houses have ice even when they are in their early twenties because so much heat escapes into the attic that they can cause a 20-degree attic to be above freezing. It was strange to see my house with ice and then places in the city that I know have serious problems with not having ice at all.