Ice Dam Problems
Signs of Ice Dams
Does your house look like this one in the winter? I drive down the road all winter long and see house after house with the tell tale signs of ice dams. Those massive icicles hanging down from the roof eaves are a sure sign of a potential ice dam problem in the near future.
Ice dams are the result of several factors all working at the same time. They include:
- Inadequate ceiling insulation
- Poor soffit and ridge vent ventilation
- Cold temperatures
- Sunny days
Ice dams are formed when warm air leaks into the attic space and warms the roof enough to start melting snow. This combined with snow melting from the sun causes the melting water to start running down the roof towards the eave. As the melting water reaches the edge of the roof it ends up over the part of the roof that’s cold and it freezes.
As the cycle continues the ice builds up a dam near the eave. This causes the continuing melting water to back up behind the “ice dam”. When the water get’s deep enough it begins to back into the shingles and leak into your home.
How To Prevent Ice Dams
Preventing ice dams is a fairly easy process. Obviously it will cost some money but the cost of it should pay back in better energy efficiency within your home. The steps necessary to prevent ices dams are:
- Improve the insulation in your attic. This might be achieved by installing another layout of fiberglass batt insulation. Another option which I prefer is to install a layer of blown-in cellulose attic insulation. This will help eliminate heat loss from your home that causes roof snow to melt. Obviously this should help reduce your heating and cooling bills.
- Install sufficient soffit vents and an adequate ridge vent. This can be quite a job and one that might be better tackled by a professional. It’s really important to clock off air flow to gable end vents if they are present as they “short circuit” the soffit / ridge vent system. The soffit and ridge vent allow cool/cold air to travel up along the underside of the roof to help prevent snow melt.
- The next time you have new roofing installed be sure your roofer installs several feet of an Ice and Water shield product to help guard against water damage due to ice dams.
- I also recommend that you use a roof snow rake to remove snow from the roof eaves after snow storms. This allows the sun to continue melting snow along the edge to prevent the ice dam from forming.
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Hey Todd,
Timly and Excellent article with great tips!
In my experience, ice dams usually occur after a heavy snowfall and several days of freezing temperatures. Warm air inside your home leaks into the attic and will warm the underside of the roof causing snow and ice on the roof to melt.
The most likely causes of ice dams are due to heat loss, air leakage and the general warming of the house structure due to conduction from the heated building.
The heat loss remedy is an easy one – add insulation like you suggested. It’s stopping the air leakage that can give your readers the best bang for their buck!
Sealing air leaks into the attic allows the insulation to do it’s job. Warm air can flow from the house into the attic space – insulation alone will not stop air leaks.
~ concord carpenter
Another timely bit of info from you! This is just one of the myriad reasons why I so appreciate your newsletter! Thanks again.
[...] snow can damage a roof and even cause it to collapse. Use a snow roof rake to help lessen the load. Ice dams are another potential problem that occur when heat escapes, melting the snow only to have it [...]
Good information for homes where attic space is not used as livable space. Looking for answers for those of us with attics that are used as livable space (1952 1-1/2 story cape cod). Where can one find more technical information on the dynamics behind the ice formation? And where can one find more information about companys that can do spray foam insulations? What companies are the major suppliers of spray foam insulation?
@ Liz – Can you describe your space for us? If so we may be able to explain the situation.
Freezeblock prevents water damage to homes from ice dams.