The frost itself doesn t do any damage but once it melts things get wet which is when the damage.
Frost in attic rafters.
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 moisture gets into the attic it condenses on the roof sheathing in the form of frost.
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.
What causes this type of moisture problem in the attic.
The straight forward answer is that a little frost seen in a canadian attic in the dead of winter is nothing to panic about.
Notice though that there is some migration.
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.
Some of it can cross the first rafter there but it doesn t seem to make it across the second rafter.
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 worst frost was on the other side though.
What s happening is that the rafters keep the warm air from migrating much.