Lots of ways many of which are small is difficult to detect.
Frost in attic space.
Can sun get to the roof you will have either frost or water collecting.
During winter conditions attic frost is a problem associated with attic bypasses.
Bypasses are what allow moisture in the attic to begin with and this is what needs repair.
When the moisture gets into the attic it condenses on the roof sheathing in the form of frost.
While bypasses are certainly the most common cause of frost there are other ways it can happen and these are much more obvious.
Frost in your attic space is a sign that warm humid air is somehow getting into your attic space.
Frost and ice forms in attics when warm humid air accumulates and condenses on the underside of your roof sheathing.
Depending on the temperature and the insolation ie.
Melting frost can lead to the deteriorated roof sheathing mold on the roof sheathing wet insulation and water stains on the ceilings.
When moisture gets into the attic it condenses on the roof sheathing in the form of frost.
The fix for frost in the attic is sealing attic bypasses these are passageways from the conditioned household space to the attic.
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.
How does humid air get from our house and into the attic.
Since our minnesota winters are usually dry the only other source of humid air is your living space.