North America just faced one of its coldest and most relentless winters on record. Some regions didn't see double digit temperatures for weeks at a time. Homes with improper roof insulation and/or roof ventilation, as well as attic air leaks, likely experienced the unwanted results of the harsh weather in the form of ice dams on their roof. Large amounts of snow and temperatures in the teens & twenties create the perfect weather condition for ice dams to form.
Ice dams are exactly what they sound like: ice that forms on roofs and causes water to back up. You can tell if you have an ice dam if you notice icicles forming on the edge of your roof. While icicles can be a beauty to admire, the ice dams that cause them are a real beast.
The cause of ice dams is simple as well: heat escapes through the roof, melting the snow and ice. This water runs along the roof under the snow and refreezes as it reaches the roof’s cold eaves.
Ice dams trap the melting water, halting it from draining off the roof. If it can't drain off, it just builds up. Here's the beastly side of ice dams: this melting water leaks through walls and ceilings, causing roof damage and potentially, damage to the inside of the home. Wet roof insulation in the attic will lose insulation R-value and become a magnet for mold and mildew. They can also tear off gutters and loosen roof shingles. Talk about an avoidable disaster!
Attic air leaks take first place as the largest contributor to ice dams. Finding these attic air leaks can be difficult to locate since they're almost always buried in insulation products. It can turn into a guessing game, so be sure to hire an experienced professional to seek them out. Simply adding more insulation products to an attic will not solve the problem unless the air leaks have been properly sealed.
Adequate attic roofing ventilation also helps keep the roof surface cold. If it stays cold, the ice will not melt from the bottom up and ice dams have no chance to form. Other ways to prevent ice dams and their damaging ways include:
Don't go into next winter unprepared. For a top-of-the-line complete engineered roof ventilation system and a number of high-performance polyiso foam insulation board options, visit AtlasRoofing.com/roof-insulation. For SBS roofing underlayment options that help prevent damage caused by ice dams, visit AtlasRoofing.com/roof-underlayment.