I have gotten mixed opinions on whether to vent the new fan through the roof or through the soffit eave.
Vent through roof or soffit.
For most homes the most popular and a better looking roof vent option is a soffit vent.
Turbine or rotary vents are often seen in industrial buildings commercial spots or restaurants.
If an exhaust vent is too close to an intake some of that moist warm air is headed in to the attic.
This reduces the efficiency of the vent and may trap heat or moisture in the elbows.
Mark holes for soffit venting.
Vent these fans through the roof or soffit.
Smaller on each side than the vent you re installing.
They are usually easy to remove and cut holes through.
Add soffit venting first.
One of the most used or popular roof vents is a turbine vent that has spinning tops.
A soffit vent is a type of roof vent.
And given the expectations for soffit venting and roof venting these days if an attic space is properly vented it would almost for sure preclude the soffit venting of any exhaust.
Not a good thing.
The roof contractor recommends the soffit to minimize protrusions through the roof.
However in order to make the turns necessary to penetrate the ceiling enter the attic and then descend through the soffit ductwork must make some tortuous bends.
Make the vent hole 1 2 in.
A vent through the roof must terminate a minimum of 6 inches above the roof surface or 6 inches above any anticipated snow accumulation.
A down through soffit exhaust vent design by leaving warm air in the exhaust duct when the fan is off creates a heat trap that reduces heat loss out of the bathroom through the exhaust fan duct when the fan is off in comparison with up routed vents or even horizontal vents through a gable end wall.
Vents through walls have to terminate at least 10 feet above the ground or adjacent surface but cannot be below a vented soffit.
Steve is on to something importent there.
Butt a cardboard template against the fascia and mark your soffit hole locations to begin soffit vent installation.