If you vent through the roof condensation will drip back into the interior.
How to vent a bathroom fan out the roof.
Installing a vent hood on the roof.
The 2 pipes one a 4 master and the other a 3 2nd do not go through the ceiling but into a common box that goes through the roof.
This involves running ductwork from the fan usually though an attic and out through the roof.
If you vent through a soffit where attic vents are often located the moisture will get sucked back up into the attic or roof venting.
I would recommend installing a bath fan with a new vent that goes to the gable wall roof or even the soffit last choice.
How to repair a bathroom fan.
Take the end of the duct with the connector fitting and attach it to bath vent fan.
Pass the opposite end of the duct through the hole in roof.
Bend over the tabs then nail the tabs to the roof.
Next use aviation snips to cut slits into the sheet metal sleeve.
Depending on the location of the bathroom it may be easy to vent the exhaust fan through the roof.
In all cases the ducting needs to conduct the exchaust to the building exterior and needs to terminate in an animal proof vent cover.
The master bathroom and the 2nd bathroom vent through the roof and through the same opening.
You may just want to go with a completely new vent the whole way most modern bathroom fans require 4 or 6 vent hoses for much better performance and lower noise.
Run a thick bead of tri polymer sealant along the underside of vent hood.
Bathroom ventilation fan duct routing routing a bath vent duct down out or up through an attic or roof out.
Each fan vents separately out the roof.
I recommend that my clients vent their bath fans out a gable wall if at all possible when not using an hrv or erv that is.
It eliminates the need for routing ductwork through the house and these fans usually dry the bathroom more quickly.
If you have two bathrooms that are close together and one has an exhaust fan and the other doesn t you might be wondering if you can tie a new exhaust duct into the existing one.
The 2nd bathroom vent drips on the floor and is ruining the ceiling.