We are constantly trying to reduce water vapour in the home because this prevents the build-up of condensation and the growth of mould. If you have a bathroom exhaust fan which isn’t flued to the outside atmosphere, this means all your exhaust fan is doing is transferring the water vapour from your bathroom into your home’s roof cavity.
When water vapour is transferred to a closed off space like a roof cavity, it will condense and with these ideal conditions, mould growth will occur.
As you can see from our photos here, an electrician is replacing the old exhaust fan in a bathroom with an industrial model (Fantec brand). The exhaust fan is then flued through the roof cavity to the outside atmosphere. This way, the water vapour is transferred out of the house completely and mould growth is discouraged.