It is beginning to look a lot like Christmas. The family is in town, chestnuts are being roasted, and everyone is waiting the return of St. Nicholas. But during this holiday season, a wintery grinch is waiting and plotting to steal away your peace and ruin your home. While everyone knows about the crazy ice, terrible cold, and vicious ice storms that happen in Oklahoma, one manifestation of winter that can affect your home the most is something you have probably never heard of, Ice Dams.
An ice dam is a ridge of ice that forms at the edge of a roof, or soffit, and prevents water and melted snow from draining off of the roof. Water will then get backed up behind the dam and gets pushed back up the roof, which will create a leak into the home and can cause damage to insulation, furniture, appliances, ceilings, walls, and other areas. This happens across the country, but many people don’t know how it happens, or how to prevent
The creation of an ice dam is the result of a complex relationship between the amount of heat lost from a house, ice and snow accumulation, and outside temperatures. For ice dams to form there must be snow on the roof, and, at the same time, higher sections of the roof’s outside surface must be above the freezing temperature, while lower areas of the roof are below 32. The snow on a roof surface that is above 32 will melt. As water flows down the roof it reaches the portion of the roof that is below 32 degrees Fahrenheit and freezes. When the water freezes, the dam grows, and water above backs up behind the ice dam but remains liquid. Shingles are layered on top of each other and designed to prevent water that is flowing downward from entering the house. But when the water is pushed up from the bottom underneath them, it finds cracks, spaces, and openings in the exterior roof covering and flows into the attic space. From the attic it will flow into exterior walls or through the ceiling insulation.
As we have established, roofs with different temperatures cause ice dams to form, but what causes the roof surface to have different temperatures? Since most ice dams form at the soffit of the roof, there is obviously a heat source warming the roof elsewhere. This heat is generated from the home itself. In rare instances solar heat gain may cause these temperature differences, but not often.
Heat travels and is transferred in three ways: conduction, convection, and radiation. Conduction is heat energy traveling through a solid. An example of this is the heating of a cast iron frying pan. The heat moves from the bottom of the pan to the handle by conduction. If you put your hand above the frying pan, heat will reach it by the other two methods. The air right above the frying pan is heated and rises. The rising air carries heat and energy to your hand. This is heat transfer by convection. Heat is also transferred from the hot pan to your hand by electromagnetic waves also called radiation. Another example of radiation is to stand outside on a bright sunny day and feel the heat from the sun. In a house, heat moves through the ceiling and insulation by conduction through the slanted portion of the ceiling. In many homes, there is little space in regions like this for insulation, so it is important to use insulations with high R-value. If the home’s R-value isn’t high enough, the insulation does not keep the heat inside the house and the surface of the insulation will be warmer than the other surroundings in the attic. Therefore, the air just above the insulation is heated and rises, carrying heat by convection to the roof.
The roof can also be unevenly heated due to air leakage. In many
The best way to prevent and deal with ice dams is to control the heat loss from the home and to remove snow from the roof. This eliminates one of the ingredients necessary for the formation of an ice dam. In an emergency situation where water is flowing into the house structure, making channels through the ice dam allows the water behind the dam to drain off the roof. Hosing with tap water on a warm day will do this job. Work upward from the lower edge of the dam. The channel will become ineffective within days and is only a temporary solution to ice dam damage. Hiring professional roofers like Sparrow Construction is the only long-term way to deal with and prevent ice dams. Let Sparrow Construction give you the gift of peace of mind this holiday season.