Dangers of Freezing Water Under Shingles and Membranes

Winter has arrived, and with it, temperatures can drop below freezing overnight. If water gets under the shingles or membranes and freezes, it can cause serious damage.


If water gets below the membrane, freezes, and then thaws, it can cause the membrane to become brittle, meaning that the weatherproofing becomes compromised, resulting in leaks when it rains.

This brittleness also affects asphalt shingles. You might have to replace these shingles during the winter if the damage was severe enough, or in the early spring. Damaged shingles can result in roof leaks causing even greater damage to the home.

Damaged Felt

Though not a complete seal, the paper underneath your shingles provides some additional waterproofing. However, if water freezes underneath the shingles, over time, it can start to wear away at the paper, especially in places where it was nailed down.


As temperatures can vary throughout the day – freezing at night and then above zero during the day, all that frozen water can melt and leak into the attic and house, causing everything from ceiling and wall damage, to damaged insulation and mold.

Ice Dams

Often the edges of the roof are cold, but other parts of the roof get above freezing. This will melt any snow or ice in those warm areas, melt down, and then freeze at the edge of the roof, creating an ice dam that grows as more water is trapped and frozen. Ice dams in and of themselves are not a problem; it is when they start to melt that dangerous leaks can occur.

If you believe you have water freezing below your shingles or membrane, the best idea is to have a roofing inspection. The roofing consultant will be able to confirm and then provide you with solutions, whether it is a simple fix or a more serious repair job.

To learn more about getting your roof inspected, talk to the Roof Tech team at +1.604.888.7663 or info@rooftechconsultants.ca