Frost In Attic Rafters

How much dripping up there before we have.

Frost in attic rafters. Notice though that there is some migration. The frost itself doesn t do any damage but once it melts things get wet which is when the damage. What s happening is that the rafters keep the warm air from migrating much. When the moisture gets into the attic it condenses on the roof sheathing in the form of frost.

When the outside temperature rises again the frost thaws water collects and can leak into your house. Sticking my head into hundreds of attics every year i see lots where. The straight forward answer is that a little frost seen in a canadian attic in the dead of winter is nothing to panic about. 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. Some of it can cross the first rafter there but it doesn t seem to make it across the second rafter. Our dryer vents up through the attic to the roof. 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.