Ventilation solutions to an Existing fan, that won’t cost the earth.
Ventilation For Existing Exhaust Fan
Most existing bathroom exhaust fans simply extract moist air directly into the roof space rather than outside the roof externally. This will cause damage inside the roof over time.
A passive ventilation system can be retrofitted and installed over an existing fan inside the roof cavity. It is then ducted out the roof externally to a passive vent cap and appropriate roof flashing to suit the roof type.