When the moisture gets into the attic it condenses on the roof sheathing in the form of frost.
Frost in attic rafters.
Sticking my head into hundreds of attics every year i see lots where.
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 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.
The straight forward answer is that a little frost seen in a canadian attic in the dead of winter is nothing to panic about.
When the weather warms up the frost will become water droplets and evaporate harmlessly.
During winter conditions attic frost is a problem associated with attic bypasses.
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.
What causes this type of moisture problem in the attic.
The worst frost was on the other side though.
Notice though that there is some migration.
Some of it can cross the first rafter there but it doesn t seem to make it across the second rafter.
How much dripping up there before we have.
The frost itself doesn t do any damage but once it melts things get wet which is when the damage.