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.
Fan in attic ice dam.
Houses with good attic ventilation generally do not experience ice dams and the physics are quite simple.
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.
Here in minnesota we get quite the snow filled winter.
The key to preventing ice dams is simply to keep your attic and roof cold.
This rim can grow trap more water behind it and bingo you have a full fledged ice dam.
There it freezes creating a rim of ice.
If you re wondering how to fix an ice dam on your roof here s how you can prevent them altogether or remove them if they ve already formed.
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.
Simply insulating your attic will keep your home warmer and your attic cooler.
Not to mention soggy insulation in the attic which loses r value and becomes a magnet for mold and mildew.
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.
That s why attic fans are a non starter for ice dam prevention.
Ice dams on roofs attic moisture attic mold.
And with our unpredictable weather and temperatures we are at a high risk of getting ice dams.
But codes don t address all the issues and many houses are built without following building codes.
In addition seal all the places that warm air can escape into the attic like areas with wires and plumbing lighting fixtures heating fixtures chimneys etc.
When the meltwater runs down the roof it hits the cold edge not warmed by the attic.
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.
See below for a shopp.
An ice dam is a build up of ice on the eaves of roofs that results from melting snow under a snow pack.
And if the building uses a whole house ventilating fan especially if there is inadequate exit venting for the fan operation.