I have a metal elbow joint that is leaking. It is connected to an exhaust fan in the bathroom and runs to the roof. What can I wrap the elbow with to stop the leak?

  • In addtion to @Ecnerwal's answer, it's also possible, if it's installed badly and the outside vent is bad/broken, that driving rain could be making its way in. Likewise, water leaking down from an eavestrough or something else could be flowing inside. These of course are all other major issues that we'd need more information to solve. Is it only happening during rain, or after you use the vent after a shower/etc? Can you take any pictures of the outside vent or the pipe from within the attic?
    – gregmac
    Dec 19, 2013 at 19:36

1 Answer 1


Leaking air, or leaking water?

If leaking air, either replace it if it's degraded, or try duct joint sealant (which stands a somewhat better chance of lasting than duct tape.)

some joint sealant

"Leaking" water - a bathroom exhaust vent needs to be heavily insulated all along its length, and should preferably run straight up, then turn and slope gently to the outside, so that water which condenses out of the air can run outside, rather than collecting in the vent and leaking out. Correcting one that's been "leaking" a while may require replacing any corroded sections of vent, improving the routing to more closely match the ideal mentioned above, and wrapping it in insulation. If the joints have been made "the wrong way" (male end inward) you may have to completely re-fit the vent pipe.

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