Ice Dams

Signs of Ice Dams

ice dam2 Ice Dam Problems

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 dam detail Ice Dam ProblemsIce 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 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.

Adding More Insulation May Cause More Damage

So at the beginning of the article I mentioned some ice and water damage at an elderly housing facility. The explanation is rather complicated but worth pointing out.

About a year ago the facility decided to add some additional blown in cellulose in the attic space above a dining room. The dining room is on the first floor with attic space above it. The attic/roof over the dining area runs up the building and meets the 2nd story attic above the main living portion of the building. In essence the dining room looks like  a shed roof formed off the main roof.

So after insulation the attic above the dining area only that space had sufficient insulation in place to keep the air and roof very cold (just what is wanted on a roof in this part of the country). The problem is that the upper portion of the attic did not receive the additional insulation and it was a much warmer space. Remember the two spaces are adjacent to each other and share a common roof plane.

So as snow melted on the upper roof from the warm attic air the water ran down the roof until it hit the lower roof with the colder attic. That lower roof was cold enough that the water froze. Essentially the entire lower roof became a skating rink with catastrophic results. Water was pouring into the space ruining the ceiling, insulation, flooring and wall finishes.

I bring this up so that people realize that careful analysis and consideration must be used when adding additional insulation to your home. Be sure you understand the entire roof mechanism and what causes ice dams.


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