Fan In Attic Ice Dam

Ice dams on roofs attic moisture attic mold.

Fan in attic ice dam. An ice dam is a build up of ice on the eaves of roofs that results from melting snow under a snow pack. Houses with good attic ventilation generally do not experience ice dams and the physics are quite simple. But codes don t address all the issues and many houses are built without following building codes. Posted november 18 2019 by lewis insulation filed under attic ventilation.

Condensation snow on roof and ice dam prevention tips building codes have some requirements that attempt to prevent the problems of ice dams and attic condensation. And with our unpredictable weather and temperatures we are at a high risk of getting ice dams. When the meltwater runs down the roof it hits the cold edge not warmed by the attic. Not to mention soggy insulation in the attic which loses r value and becomes a magnet for mold and mildew.

Simply insulating your attic will keep your home warmer and your attic cooler. This rim can grow trap more water behind it and bingo you have a full fledged ice dam. Only running the fan in the summer extended its life and it will cause more harm even to the fan motor itself in the colder months and it does not allow the fan to reduce moisture build up in the attic at all at these times and does not allow the fan to prevent ice dams during the winter. Here in minnesota we get quite the snow filled winter.

Ask this old house general contractor tom silva explains the best ways to keep your roof and gutters free from those dreaded ice dams. An ice dam forms when the roof over the attic gets warm enough to melt the underside of the layer of snow on the roof. There it freezes creating a rim of ice. And if the building uses a whole house ventilating fan especially if there is inadequate exit venting for the fan operation.

The water trickles down between the layer of snow and the shingles until it reaches the eave of the roof which stays cold because it extends beyond the side of the house. Guide to detecting and correcting attic condensation and preventing ice dam leaks in buildings can reduce the chances or correct the causes of mold in attics. How to prevent ice dams use heated cables. See below for a shopp.

By circulating cool outside air in the attic space or in the rafter spaces just below the roof deck the roof surface remains below freezing and cannot melt the snow on the roof. That s why attic fans are a non starter for ice dam prevention.