While kids may like to play with them and others actually like their fascinating designs, ice dams are dangerous. Whether it be for your children, your roof or your wallet, learning basic ice dam prevention techniques will undoubtedly pay off in the long run.
Ice Dam Formation
Ice dams are caused by warm roofs and cold eaves. When snow accumulates on a roof with insufficient insulation, the snow begins melting near the ridge where the hot air rises first. The melted snow runs down the warm roof under the snow pack until it reaches the overhang, which is not warmed by attic air. Here the water begins to freeze again. It may be seen as long icicles at first and the ice dam itself may not be evident under the snow.
Serious problems to a roof and house can result from the ice dam. As the dam grows higher, water backs up behind it and eventually seeps under the roof shingles, between the roofing felt, through joints in the roofing deck, and then into the house.
Ice Dam Prevention
Electric heating cables strung along the lower edges of the roof are often used to prevent ice dams, but have limited success. Ice dams often form above them and the damage continues.
The best ice dam preventive measures are a cold roof and adequate air circulation in the attic. Warm air reaching the roof must be minimized by placing insulation not only between the ceiling joists, but also between the rafters. The insulation must be carefully installed with no openings for hot air to reach the roof. The ceiling insulation must run to the plate line (top of the stud walls) but not block any soffit vents.
Additionally, you should consider removing snow from your roof once it gets to a certain point. According to Roof Snow Removal 101, one square foot of snow that is one inch deep weighs about one pound. Bear in mind, ice dams bring about much more force than average snow. One cubic foot of ice weighs 57 lbs.
To remove snow from your roof, invest in a roof rake. They are designed to remove snow from the roof without damaging the shingles or gutters. For more tips and guidelines around removing snow from your roof, please click the link above.
Other prevention tactics deal with the air in the attic. Air must be allowed to circulate in the attic and be efficiently removed. A continuous ridge vent is the best means, but roof vents work well too. Fans on thermostats can also be mounted at screened openings on gable end roofs to remove warm air.
Another important preventive measure is to install an impermeable ice and water membrane under the roofing material. It should extend from the edge of the eaves to at least two feet past the perimeter wall line. This material has one sticky side that bonds to the roof deck. It also seals around nails driven through it.
Ice Dam Solutions
Emergency solutions, however, are sometimes required. If water is leaking into your house because of ice dams, there is one way to deal with it safely and easily. Fill one leg of an old pair of panty hose with calcium chloride and lay it vertically on the roof across the ice dam. Calcium chloride (CaC12), which is highly effective at melting ice, will cut through the ice and open a channel to release the backed up water. Moreover, it will keep the channel open.
Working from a ladder, the socks full of calcium chloride can be positioned on the roof by using a rake or long stick. This eliminates the necessity to climb on a roof made perilous by snow and ice.
Ice dams are fun to look at, but present a serious risk to your roof and your family. Keep the preceding tips in mind the next time you are standing pat watching the ice melt.