My Attic Has Frost

Since our minnesota winters are usually dry the only other source of humid air is your living space.

My attic has frost.

The exhaust from the rooms below gets released into the open air in the attic if not sealed properly causing lots of moisture in the air. That s about it pretty simple. When the moisture gets into the attic it condenses on the roof. Attic frost is the result of conditioned air leaking out of your home in the winter.

When warm air from inside the house escapes traveling up through the bypasses the moisture condenses on the roof boards and rafters where the frost can form. Insulation is irrelevant when your attic bypasses are left open for warm air to pour into the attic. A bathroom vent has been left to pump warm air into the attic. Where the water comes from.

If it s due to air infiltration from the living space then air sealing should be the first thing you do not the last. So the short answer is yes this is something you should fix. Many people s first instinct when they notice frost in the attic is to add insulation. What ends up as frost in the attic starts as water somewhere else in the house.

Frost in your attic space is a sign that warm humid air is somehow getting into your attic space. It can lead to mold wet insulation and find a way back into the home resulting in water stains on the ceiling. See the picture above. To start frost shows up in the attic when moisture laden air from the house gets into the attic.

That is not a solution.