The answer to 'why is my roof vent leaking' is that there are several common causes, including improper installation, damage to the vent flashing, or deterioration of the sealant around the vent. Symptoms of a leaking roof vent can include water stains on the ceiling or walls around the vent, mold or mildew growth, and even dripping water.
In many cases, a leaking roof vent can be fixed with some basic DIY repairs, such as re-sealing the vent flashing or replacing damaged components. However, if the issue is more complex, such as structural damage to the roof or the need to replace the entire vent, it's best to call in a professional roofing contractor to assess and resolve the problem.