My Attic Has Frost

Insulation is irrelevant when your attic bypasses are left open for warm air to pour into the attic.

My attic has frost.

What ends up as frost in the attic starts as water somewhere else in the house. See the picture above. To start frost shows up in the attic when moisture laden air from the house gets into the attic. Since our minnesota winters are usually dry the only other source of humid air is your living space.

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. Attic frost is the result of conditioned air leaking out of your home in the winter. Where the water comes from. Frost in your attic space is a sign that warm humid air is somehow getting into your attic space.

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. During winter conditions attic frost is a problem associated with attic bypasses. That s about it pretty simple. It can lead to mold wet insulation and find a way back into the home resulting in water stains on the ceiling.

That is not a solution. Therefore my suggestion is that if one finds frost in the attic one first has to identify which of the three causes is contributing to the problem. If it s due to air infiltration from the living space then air sealing should be the first thing you do not the last. Many people s first instinct when they notice frost in the attic is to add insulation.

A bathroom vent has been left to pump warm air into the attic.