Ice dams are sadly a reality in colder environments when snowfall is extreme. At their core, ice dams are a symptom of poor attic insulation or ventilation. Of course with extreme snowfall amounts even the best insulated and ventilated attics are subject to ice dams and the icicles that drip from the sides of your gutters. Simply stated, an ice dam results when warm air in an attic melts the lower level of snow on a roof, but before the water can properly drain into the gutter at the eave it refreezes where the roof temperature cools at the edge. Soon more water joins it and refreezes, causing an additional layer of ice to build. Eventually this layering of ice becomes so extreme that it begins to back up under the adjoining shingles, thereby seeping into the attic and into your home. Sometimes proper installation of an ice and water shield membrane under the bottom rows of shingles (this is a thick layer of mastic tar) can help to avoid the resulting damage from ice dams, but sadly even it may not adequately protect your home from extreme snow and weather events – although it will certainly give you more of a fighting chance. Unfortunately this should also be installed at the time of the initial roof installation – not after the first leak.
So what can you do after the ice dam has formed? Most of the time, depending on the slope and height of the roof, this may be a waiting game. Unfortunately there may be nothing more that can be done than to break off the icicles with a rake or shovel to relieve pressure on the gutter and physically remove the ice dam with a garden rake if accessible. As would be expected, extreme caution should be use when removing icicles to avoid physical harm and never should ice dam removal be attempted from any other location other than the safe proximity of the ladder (and most often by a professional repair company). You should never attempt to climb onto a roof while snow or ice is present. If removal is attempted from a ladder not only must the ice be removed with mechanical action pulling down the slope of the roof (to avoid breaking off shingles) but to prevent future ice dam issues, you should also provide channels for additional water to make its way to the gutter.
Contrary to some suggestions, rock salt or other melting products are not recommended for use on ice dams. Not only will they prove ineffective in most situations, but they often can cause staining and permanent damage to the roof, possibly resulting in additional leaks. I have heard of some suggestions where they advocate using a chemical ice melt product contained in a sleeve of panty hose at the eave, but this is not recommended by roofing material companies and may in fact create yet another blockage to any water drainage unless placed directly above the gutter before the ice dam starts. In the current context this is often not an option as we are addressing the problem after the ice dam has already developed.
Will mechanical removal work? Possibly, but the reality is that once an ice dam forms there may not be much you can do until the temperature rises above freezing. After all, in freezing temperatures any new channels or paths you create will be quickly frozen shut as additional water refreezes and creates a new ice dam. And in this situation, most people find it best to simply “wait it out” and focus on mitigating the interior damage. Tarps can sometimes be used if the ice dam can be removed, but even they are subject to ice damage leaks as the ice eventually makes it way under the tarp and into the home. They may provide protection for several days, but as the ice rebuilds the leak returns.
A symptom of severe snow events, ice damming can be best prevented by proactive efforts in the warmer months. With adequate roof ventilation, additional insulation and clear gutters, most ice damming problems can be prevented. Now is the time to take action, thus avoiding headaches later in the season.