The polar vortex, snow storms, freezing rain …. We are barely a month into winter and weather conditions have forced businesses to shut down, have wreaked havoc on the roadways, and have caused schools to use up all of their “snow days” already. But did you know that there’s something even more insidious going on, possibly right above your head? These weather conditions create the “perfect storm” for leaving your home, and especially your roof, susceptible to damage. That’s because roof ice dams occur when heavy snowfall melts and refreezes on roofs. Thick accumulations of snow and ice that form over the eaves of a house, ice dams might look picturesque, but the damage they can create is far from pretty. Beyond the icicles, what you can’t see is the water that collects behind the dam, gets under shingles and gradually seeps into the house.
Which Homes are Most Susceptible to Roof Ice Dams?
If your home has a low pitched roof or if your attic is poorly insulated and/or ventilated, it’s more likely to get ice dams. But even higher pitched roofs can get ice dams. That’s because the main cause of ice dams is a warm roof. When the roof is warmed from underneath (by heat escaping from the living areas of your home through the attic), the snow melts, sending water sliding to the gutters and eaves, where it refreezes. As the process repeats itself, eventually the ice that is backed up at the eaves blocks the water. When the water has nowhere else to go, it seeps under the shingles and eventually into the living areas of your home.
What Kind of Damage Can Ice Dams Cause?
According to the US Department of Energy, ice dams account for millions of dollars of structural damage every year, including water-stained ceilings, dislodged roof shingles, sagging gutters, peeling paint, mold and damaged plaster. Gutters can eventually break away under the heavy weight of accumulated ice. Water seeping into your attic gets onto your insulation, making it much less effective, costing you more money to heat your home, and creating a repeating cycle of poor insulation, warm roof, ice dams and leakage.
Water often leaks down inside the wall, where it wets wall insulation and causes it to sag, leaving uninsulated areas at the top of the wall. Again, that costs you more money in heating bills, but more importantly, moisture trapped inside the wall causes mold and mildew to form on the outside.
Peeling paint, mold and damaged plaster might not be visible right away. The visible signs of this type of damage present themselves long after the ice dams are gone. As water from the leak dampens building materials and raises the humidity inside the wall, the moisture tries to escape (as either liquid or vapor) and wets the interior and exterior walls. As a result, the walls shed their skin of paint.
Preventing Ice Dams
There is still plenty of winter left, so it’s important to take steps now to prevent ice dams and minimize any damage that’s already occurred.
Clean debris, snow and ice from gutters and down spouts. Do not try to hammer, saw or throw salt on an ice dam.
Use a roof rake to clear snow from your roof. Don’t use shovels, ice picks, etc. They can cause expensive damage to your roof and put you in danger of falling ice.
Make sure your attic is sufficiently insulated and ventilated. Replace wet or damaged insulation. Maintaining airflow from under the eaves of the soffit area through roof vents helps prevent ice dams.
Install a snow and ice shield beneath the shingles covering the overhang of the roof.
Invest in CertainTeed’s Winter Guard Shingles, which are specifically designed to prevent winter damages, such as ice dams, and protect the most vulnerable parts of your roof.
Protect your gutters with Rhino Gutter Guards, which will keep snow and debris from clogging your gutters. This helps eliminate the added weight a heavy snowfall can dump on your roof.
Line the outskirts of your roof with heated cables, which help to equalize your roof’s pressure by heating it from the outside.
The most important thing to remember is that keeping the entire roof cold will prevent ice dams. In most homes this means blocking all air leaks leading to the attic from the living space below, increasing the thickness of insulation on the attic floor, and installing a continuous soffit and ridge vent system. Be sure that the air and insulation barrier you create is continuous. Not only will this help prevent ice dams, it will make your heating system more efficient as well.