Installing Bathroom Fans

If you’ve added a bathroom to your home or have condensation problems in an existing bathroom, installing a bathroom extractor fan to vent through an outside wall is an easy job for a DIY home enthusiast.

If the fan is to ventilate a shower stall it must be an in-line fan; the grill for the fan will be in the ceiling above the shower and a length of ducting then runs to the electrical components, otherwise a wall mounted fan will be quite adequate.

Fans can generally be wired into the lighting circuit of your home but, obviously, being in a bathroom it is essential to keep any electrical wiring and components well away from any risk of water getting into them. As with all electrical jobs around the home - check for any local regulations on what you are allowed to do, rather than having to get a qualified electrician in to do the job.

Installing an In-line Bathroom Fan

Unless an obstruction makes it impossible the most common position for an in-line fan is in the ceiling above the shower; so for the following description you’ll mainly be working in the roof space.

Having cut a suitable hole into the ceiling plasterboard, or sheetrock, of the shower cubicle - an interior vent can be secured across it. To this vent attach a length of flexible ducting, up and at least six inches away from the vent, bend it through a right angle and continue it on for at least another six inches towards the nearest outside wall.

On the next joist along, securely mount the in-line fan and connect it to the electrical supply following the manufacturer’s instructions. Connect the piece flexible ducting to it and then run another piece of ducting from the fan to the outside wall. Hopefully you’ll be able to position this last piece of ducting so that it can exit through a fascia or soffit board.

Drill from inside the loft space through to the outside so that you can see where you need to position the outer vent cover. If it is in a fascia or soffit board you can create the hole with a suitable saw.

If you have to create a hole through the masonry you’ll need a core drill bit. If you don’t own one of these you should be able to buy or hire one from your local DIY store.

Finally, the in-line fan switch can be wired in to the lighting switch for the bathroom or shower cubicle, or alternatively you can create another small hole in the ceiling, away from the shower cubicle, from which you can install a pull-chord switch.

Installing a Wall-mounted Bathroom Fan

Without positioning it near to a shower unit - position the fan so that it is as high up a wall as it can be and ideally is opposite the door to the bathroom. A wall mounted fan is fitted on the inside of the bathroom wall and vents directly to the outside, so you will need a masonry core drill bit, as mentioned above.

However, if the fan is required in a bathroom with no external wall, you can run ducting from the fan to a suitable venting point on an external wall. Connecting the fan to the electrical supply and fitting a switch is the same as for an in-line fan.

Bathroom Fan Ducting and Vents

The external vent for a bathroom fan is usually a louvered one. These have thin hinged slits in them which are blown open by the force of the fan; otherwise they remain closed preventing moisture or insects from getting in.

Whilst using flexible round ducting is most common you can also get rigid ducting that is both round and rectangular in cross-section; and to cover long distances it might be preferable to use a rigid ducting. You can buy adaptors and connectors to join round and rectangular, flexible and rigid, ducting.