Ice Dam Solutions

Air Sealing. This is the practice of restricting the movement of air from the heated living space into the unheated attic space - whether open or cathedral. This entails the use of vapor barriers on the heated side and sealing all penetrations and holes leading to the attic space - including plumbing vents, exhaust vents and can lights. This is the most important aspect of minimizing ice dam formation. This is a must on all new construction and should be performed as permitted on existing homes.

Insulation. Installing or adding the proper amount of insulation for your area. In the upper midwest it is recommended to have R49. Other areas require different amount. Local building codes should dictate. Insulation provides a moderating of temperatures between two areas. Without proper air sealing additional insulation may not provide much relief from ice dams.

Ventilation. Proper ventilation is balanced ventilation. Intake at the eaves is balanced with exhaust at the ridges or upper peaks of a roof. Ventilation additions or improvements need to be done in conjunction with air sealing and insulation improvements. Modest temperature differences between attic and outside air means that passive ventilation (roof and eave vents) moves very little air. The idea is that 'drafting' occurs. The colder air at the soffit/eaves pushes the warmer air out through the ridge. In order for this to work, it requires larger temperature differences than are usually present in the winter. The meager amount of air movement cannot keep up with unchecked heat loss. To make matters worse, some have turned to the use of power ventilation with humidistats. The idea is that as the humidity level builds in the attic, these fans will turn on and expel the hot, moist air. However, often the aggressive pulling of air through these fan vents draws warmed air from the living space - compounding the problem.

The issues are complex. For sure, a competent contractor or home performance analyst is needed. With the complex design of houses and current and past building practices, solving ice dam problems can be difficult. Doing it right can cost tens of thousands of dollars. Short cutting may result in lack luster results or worse - a sick house. All that can be done on the inside - air sealing, insulation, ventilation - may not prevent ice dams from forming and causing problems. Temperature fluctuations, the insulating effect of snow and solar radiation can and do lead to ice dam formations.