Although icicles hanging off a roof may look old world pretty, they generally mean just one thing — ice dam.
An ice dam is an accumulated mass of ice that forms at the edge of a roof and prevents melting snow water from draining into the gutter. As the draining water meets the ice dam it begins to back up and eventually seep under the roofing material — causing problems both inside and outside the home. As well as damaging shingles and gutters, ice dams can create water damage to insulation, walls, ceilings, and floors.
Ice dams occur when there is a lot of snow on the roof and the temperature of the upper part of the roof is above freezing but the lower portion near the gutters is below freezing. Generally speaking what is happening is heat from the home is getting into the attic and warming the roof, causing the snow to melt. But since the air is still below freezing the water turns to ice near the gutter line, causing a dam of ice. Next time it snows, take a look at some houses in your neighborhood and see where the snow is melting first to get a better idea of how much variance in heat a roof can have.
The best way to deal with an ice dam is to prevent it from happening in the first place. A well-sealed and insulated attic generally does not have ice dams because the roof will not have uneven heat. Increasing ventilation in the attic space under the roof and sealing any possible air leaks will also help maintain an even roof temperature.
If an ice dam has occurred, however, action has to be taken immediately to try to minimize the damage. Just be sure that whatever action you take will not make the matter worse as clearing snow and ice off the roof can seriously damage the roofing materials and only cause more problems down the road.
It’s also important for homeowners to realize how dangerous working on a roof can be – especially in the wintertime. Calling a professional roofing contractor is always the safest option.
Of significant note: roofing manufacturers have created new products in recent years that aim to prevent leaks caused by ice dams by creating an impermeable barrier to water wherever they are installed. Certainteed’s WinterGuard is one such product which is made from asphalt polymers and formed into a rolled sheet. New products such as these can either be used just in problem – or potential problem — area or for the entire surface of the roof if deemed necessary. They are, however, designed to have a regular roofing material applied on top.
