Vent pipe leaks during heavy rain can occur if you have cracks in your vent pipe boot or flashing.
Roof vent leak from snow.
Snow can get into any weak areas on the roof as the melting causes ponding which seeps into the building.
Another problem with snow is it could melt and refreeze.
Exhaust vent condensation this is a very popular source of the winter roof leak phone call we receive.
While you are on the roof walk along the entire length of the ridge vent.
Most ridge vents have a plug at the gable end of the roof so be sure it is there and secure.
The roof must be made colder.
There should be a fastener every 18 inches.
Leaks due to snow or rain driven into the attic through louvres or vents acceptable performance condition attic vents shall be installed in accordance with the building code and prevent the entry of rain snow and insects.
To do that install insulation or more insulation in the attic floor and keep it out of the eaves and soffit vents.
When your roof was installed each vent pipe received a flexible boot to seal water around the round surface of the vent pipe.
You should inspect your ridge vent annually.
Inches of snow adds weight to your flat roof as the extra weight can cause sagging and leaking before it ultimately collapses from too much distress.
Similar to attic frost related leaks this problem is related to the accumulation of frost inside an exhaust vent commonly a bath vent duct where it travels through an unheated attic.
Look to see if the fasteners are still in place.