Dealing with Ice Dam
Ice dams are formed by either the sun, or loss of heat from your home causing the snow on your roof to melt. Water begins to flow under the snow as it travels down the roof. When the air temperature is significantly below freezing, the temperature of the roof deck, gutters, flashing and downspouts are below freezing as well and when the melted water hits these cold surfaces it begins to rapidly freeze and eventually, the gutters and downspouts are clogged with ice. This ice buildup continues at the gutter level and the ice becomes thicker. Meanwhile, the melted water continues coming down the roof. Depending upon the rate of melting vs. the rate of freezing, you may or may not have a problem. If the water is melting at a faster rate than it can freeze, it begins to back up underneath the roofing materials. This water then finds its way to the roof deck and eventually can find its way into your home. Although ice dams can form anywhere on a roof, they form most readily at the bottom edge of roofs, valleys and areas where the slope might change on a roof.
Preventing the Leaks
It is virtually impossible to stop ice dams from forming. Some methods attempt to use heated electrical wire which is applied to the lower edge of your roof or which sits in your gutter. Often these methods have little effect and they are installed well in advance of the winter so are of little use once the problem is here. And they pose a potential shock and fire hazard as well as require someone to climb a ladder to install them.
Newer technology has leaned in the direction of not trying to stop the ice dam from forming, but to simply stop the water from entering a home. Roofing manufacturers have developed products designed to do just that and are modified asphalt products and are commonly applied as required by newer building codes, especially in northern climates. These type products help prevent leaks caused by ice dams as well as wind driven rain. Some of these products are rubberized, while others include styrene. Some are reinforced with fiberglass mats. They work by creating a solid barrier to water wherever they are applied. It is similar to shrink wrapping that portion of your roof. When applied according to manufacturer's specifications, they can be highly effective in preventing leakage from ice damming.
Unfortunately, these products are placed during original roofing or reroofing and not in the middle of winter. These products generally have one side which is very sticky and are designed to be installed directly on the wood decking of the roof starting at the gutter line. Often these materials are installed at other potential trouble areas: low slope roofs, valleys, slope changes, hips, rake edges, dormers, skylights, flashing areas. These products are designed to have other roofing materials applied over them. Since these materials are very pliable and manufactured with different compounds, any nails which penetrate the products seal themselves. In ice dam situations, most leaking occurs within 3 feet of the gutter line. Because of this, you generally do not have to cover the entire roof with these products. However, low slope roofs, shaded roofs, and roofs that have a northern exposure are candidates for complete coverage.
Hacking away at ice dams with a hammer, chisel, or shovel can be bad for your roof—and dangerous. And throwing rock salt on them will do more to harm to your plantings than to the ice. Short of praying for warm weather, there are two stop-gap measures that are usually recommended:
Blow in cold air: Take a box fan into the attic and aim it at the underside of the roof where water is actively leaking in. This targeted dose of cold air will freeze the water in its tracks. "You'll stop the leak in a matter of minutes.
Rake it: Pull off snow with a long-handled aluminum roof rake while you stand safely on the ground.
While a permanent fix for ice dams usually requires increasing the insulation, sealing, and ventilation in the attic, there is another simple way to diminish the damage after the dam has formed that I have never used but have heard it works.
- Fill the leg of discarded pair of panty hose with a calcium chloride ice melt. Lay the hose onto the roof so it crosses the ice dam and overhangs the gutter. If necessary, use a long-handled garden rake or hoe to push it into position.
The calcium chloride will eventually melt through the snow and ice and create a channel for water to flow down into the gutters or off the roof. Calcium chloride filled ice melt socks will not damage shingles. Supposedly, snow melt socks is a tried and proven method and work on sloped or flat roofs. DO NOT use rock salt because it has iron in it that leaves stains on the roof.
For the brave
Properly removing an ice dam can be quite dangerous. Some people suggest hiring a contractor to pull the gutters off the home so the whole ice dam process would be solved. This suggestion may be well intended but is wrong. Removing gutters can cause significant damage to the roofing materials and guttering systems and when the snow melts and is dropped next to the homes foundation, it can cause basements to flood. Gutters are there to remove the water.
WARNING! Performing ice dam removal is risking severe personal injury and damage to the roof if not done properly. Never walk on a snow covered roof and if you are using a ladder you follow the proper safety procedures. I highly suggest contacting professionals with the proper equipment and roofing experience to carry out this job.
Removing snow and ice dam from the roof will eliminate the main ingredients necessary for the formation of another ice dam and will usually stop the water from coming in within an hour. Using a roof rake and push broom (not water) remove the snow by carefully pulling it down the slope of the roof line. Never pull snow across the roof or it may break off the shingles and other damages. After removing some snow, carefully chip away a channel through the ice dam so the water will be able to flow through, just make sure you stop when you get close to the roofing. It's not necessary to remove all of the ice in the gutters or the ice dam itself if you have removed the snow from the roof, it will melt when the temperatures rise.
While I would not recommend anyone climbing on their roofs and there is not a simple solution to permanently correct an ice dam problem once the problem exists. Basically, the poorer the insulation and ventilation, the worse the ice damming because of heat loss through the roof. I've provided a couple of suggestions-some more dangerous than others and one that I have only heard works but some people swear by. Unfortunately some of the ways commonly suggested to correct ice dams may require someone to climb a ladder to reach the gutter or roof line, truth is there are some things people can do after the fact but preventing them in the first place is the best solution.