Frost In Attic Rafters

What causes this type of moisture problem in the attic.

Frost in attic rafters.

Notice though that there is some migration. During winter conditions attic frost is a problem associated with attic bypasses. 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. Near the ridge the frost free area extends over the garage a bit because warm air rises and it ends up near the ridge.

When the weather warms up the frost will become water droplets and evaporate harmlessly. When the moisture gets into the attic it condenses on the roof sheathing in the form of frost. Sticking my head into hundreds of attics every year i see lots where. When the outside temperature rises again the frost thaws water collects and can leak into your house.

The worst frost was on the other side though. Left unchecked frost in an attic can lead to serious mold and decay a patch of frost here and there on the tips of roofing nails poking through the sheathing for instance probably isn t a cause for alarm. How much dripping up there before we have. What s happening is that the rafters keep the warm air from migrating much.

The straight forward answer is that a little frost seen in a canadian attic in the dead of winter is nothing to panic about.