Ice Dams Prevention
Ice dams are more than just an interesting phenomenon.
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What Are Ice Dams
Between the frigid temperatures outside and the heat cranked inside, conditions are ripe for the formation of ice dams. While icicles hanging from the roof may look pretty, they could be a sign of something ugly destroying your house.
To homeowners in snowy, cold-winter climates, ice dams are a familiar sight. An ice dam is a mass of ice that gathers along the lower edge of a roofline where it overhangs the edge of the home.
Ice dams are more than just an interesting phenomenon. Severe ice dams can weigh many hundreds of pounds, compromising the structure of the roof eaves. More critically, ice dams can cause meltwater to back up under the shingles, where it can flow down and ruin ceiling and wall surfaces. If ignored, ice dams can cause serious damage to your roof, gutters, paint, insulation and interior drywall, and other surfaces.
To the uninitiated, ice dams can be somewhat mysterious, as one house may be burdened with huge blocks of ice thickly covering the roof eaves, while adjacent homes have only a bright cap of snow over the shingles with no signs of ice at all. Why is one house plagued with ice while others remain completely free? The answer can usually be found in the attic.
Causes of Ice Dams
Ice dams begin when the snow melts on an upper, warmer part of a roof, then flows down to the colder eave overhang, where it refreezes. As the ice accumulates, it forms a blockage that prevents additional snowmelt from flowing off the roof. The ice now begins to back up under the roof shingles, where it melts again, soaking the roof sheathing and leaking into the attic. There, it soaks the insulation (rendering it much less effective). It may now leak through the ceiling drywall below and into your living space. In addition to the interior water damage caused, large ice dams can be very heavy and can damage gutters and even present a safety hazard to people below.
Ice dams are formed only when the space inside an attic along the underside of the roof deck is above the freezing point. As the warm air beneath the roof heats the shingles and melts the snow on the roof, the water flows down the roofline until it reaches the overhanging eave structure and refreezes. Ice dams usually start or worsen after a heavy snow because of snow’s insulating properties. The snow layer traps warm air beneath the snow, which causes it to melt.
- Heat loss from your home through your attic and roof makes the bottom layer of snow on the roof melt.
- Melted water flows towards your gutters, where it reaches the cold eaves and gutters and refreezes.
- Over time, more water flows down and freezes, creating what’s known as an ice dam.
- Eventually, water will pool behind the dam, forcing its way under shingles and eventually into your attic, where it can cause serious damage.
Ice Dam Prevention
Every attic has air leakage through gaps and cracks that are created during the building process and home improvements. These spaces allow warm air to escape through your ceiling into the attic and through the roof. This will help eliminate the heat loss that leads to ice dams.
When your attic is under-insulated, your home lacks a thermal barrier between your living space and your attic. Raising your attic insulation to recommended levels with blown cellulose insulation will ensure that your attic is not heated by your furnace, lessening the chance of ice dams forming on your roof.
Ensure Proper Ventilation in the attic area, which keeps colder outside air circulating through the attic and prevents it from warming above the freezing point so it can melt snow on the roof. A proper ventilation system includes adequate air intake ventilation as well as adequate exhaust ventilation. Almost 75% of the homes in the United States are deficient in air intake ventilation and that is certainly the case in most homes we go into. Improper air intake ventilation will not only cause excessive snow melt and ice formation but also contributes to mold growth in the attic.
- It’s important to block any additional sources of heat loss that may be contributing to high temperatures in the attic and it’s possible that you have heat sources in your attic that you’re not aware of. Here are a few examples…
– Older Candescent Recessed Lighting – These can generate a lot of heat in the attic. Replacing these old light fixtures with modern recessed lights that can be fully insulated will help reduce the amount of heat radiated into your attic. We offer Insulated Can Light Covers to stop the flow of air through the recessed lights.
– Unsealed & uninsulated Attic Access hatch
– Open Wall Cavities, Bulkheads, Stairway Pits, or Chimney Chases
– Uncovered Whole House Attic Fans
– Electrical Junction Boxes
– Interior Wall Junctions that are not air sealed
- Other possible sources of heat include uninsulated HVAC ductwork, vents from clothes dryers, or bath and kitchen exhaust fans that vent directly into the attic.