What’s an Ice Dam?

An ice dam is a formation of ice at the edge of a roof, preventing melted snow from draining off. This trapped water can seep into homes, damaging walls, ceilings, and insulation.
The Impact of Ice Dams
When ice dams cause moisture to enter homes, it can lead to mold and mildew growth, potentially causing respiratory issues. To prevent these health risks, it’s crucial to dry out any wet or damp areas promptly and address the water source.
The Science Behind Ice Dams
Ice dams result from nonuniform roof surface temperatures. A combination of heat loss from the house, snow cover, and external temperatures play a role. For ice dams to form, there needs to be snow on the roof, with some parts of the roof’s exterior above freezing and others below. Melted snow from the warmer parts flows down to the colder sections, where it refreezes, leading to the formation of the dam.
Why Do Roof Temperatures Vary?
Most ice dams form at the roof’s edge due to a heat source warming other parts of the roof. This heat typically originates from the house, though occasionally, the sun’s heat can cause these temperature disparities.
Preventing Ice Dams
Controlling heat loss from the home is key to preventing ice dams. Weatherization contractors specialize in addressing the heat transfer issues that lead to ice dams. They can conduct tests to determine areas of excessive heat loss in your home. However, before making any interior repairs, ensure that ceilings and walls are dry. Addressing the root cause of the heat loss is essential to prevent future ice dam formation.
A Word of Caution
Working on roofs during winter poses risks. It’s always best to consult professionals for such tasks. Additionally, when making a home more airtight, ensure that ventilation and combustion devices have adequate air supply.
Note: While Exterior Pro provides this information for educational purposes, we do not offer services related to ice dams.