You can determine if a roof vent is leaking if you?

Determining if a roof vent is leaking can be effectively done by looking for water in the attic. The presence of water indicates that there is an issue with the roof vent or other areas of the roof that may be allowing moisture to enter the attic space. This can manifest as actual water pooling in certain areas or as water stains on the insulation or drywall, both of which are strong indicators of a leak.

Inspecting the attic for water provides a direct link to figuring out whether there is a problem with condensation, roof vent integrity, or other potential sources of leakages, such as improper flashing or other roof penetrations.

Other methods, such as looking for "dubs" or moisture, might not provide a definitive answer regarding the source of water ingress, as these signs can be more ambiguous. Sealing all the vents could prevent air circulation and exacerbate moisture problems without addressing the root cause of any existing leaks. Therefore, directly checking for water in the attic is the most conclusive approach to assess potential roof vent leaks.