The point of a bathroom exhaust vent or any vent really is to remove hot moist air from the house.
Vent bathroom through wall or roof.
Start in the attic and drill a hole through the roof in the desired vent location.
This involves running ductwork from the fan usually though an attic and out through the roof.
Choice is go up to roof 5 6 feet or out the present vent 15 18 feet with insulated pipe or shorten the line by going straight to side of home but this requires going up high with latter to drill a new vent hole as tight quarters in attic prevent drilling from attic.
Depending on the location of the bathroom it may be easy to vent the exhaust fan through the roof.
Try to keep it close to the fan location.
Typically an exhaust fan that is vented through the roof has a roof hood or roof cap which allows air to exhaust but provides protection from wind blown rain.
Having warm moisture laden air from a bath exhaust fan exiting out the soffit will drive moisture into the attic causing all sorts of issues with mould mildew and rot.
Here in the north we vent the bathroom exhaust through a bulkhead to the exterior wall the exhaust ducting is insulated and has a slight slope to the exterior wall to allow any condensation to escape we also install a 5 6 length of plywood at the eaves so the exhaust can t get into the attic space.
You can pass the vent through a wall instead of through the roof but it must still rise over the roof.
As for the walls rainscreen compatible intake and exhaust vents are now available.
From up on the roof use a jigsaw or reciprocating saw to cut a 4 in.
1 cut into the drain pipe you want to vent with a hacksaw.
Leave the drill bit sticking through the roof so you can find the hole.
Going to the soffet is 12 feet.
They must withstand a complete temperature range as well as damage from the sun wind branches or even hailstones.
It is because of this that many builders tend to advise against this method.
In our new house the soffits are a long way from our bathroom so the easier route was to install a wall vent outlet similar to a dryer vent outlet directly below the attic vent on the side of the house.
Previously i had helped a friend install an exhaust fan and we routed the vent out to the soffit.
If it is actually rain water coming in through the duct from the roof confirm that is there a cap on the duct if not install one.
And while both a roof vent and an overhang vent perform this task there is one big difference.
A wall exhaust depending on how close to the soffit it s located won t drive up into the attic.
Whether it s new construction or a remodel a bathroom vent should always vent through the roof instead of an eave overhang or soffit.
In the case of the roof some venting is unavoidable in order to provide attic circulation so choose roof vents that are durable and watertight.