How to Install a Roof Extractor Fan

What You'll Need
Jab saw
Safety glasses
Exhaust extractor fan
Fan duct kit
Wire stripper
Wire nuts
Screwdrivers, both flat head and Phillips

A roof extractor fan for the bathroom removes all the moisture that accumulates in the bathroom when you shower or take a bath. If you don’t use one, steam will condense and can cause mildew and mold. Installing an exhaust extractor fan isn’t too difficult. It’s a job most people can accomplish in just a few hours.

Step 1 - Selecting Your Fan

There are many different makes and models of bathroom extractor fans on the market. You will need one that’s right for the size of your bathroom. You need one that will move at least 80 CFM (cubic feet per minute), and which is not loud; the noise rating will be on the packaging. A highter CFM rating means more moisture will be extracted from the bathroom. However, a combination of higher CFM and a better noise rating will cost you more money.

Step 2 - Drilling in the Ceiling

The fan duct kit will have a template to show the size of the opening you need in the bathroom ceiling. Since the fan will fit over the opening, you don’t need to be exact. Use the jab saw to make the hole for the opening by cutting between the joists.

From here, you have to install the box that will house the fan. This will attach to the joists by screws. If you cannot attach directly to the joists, use the hanger kit that comes with the duct kit. This will suspend the box from the joists.

Step 3 - Installing the Ducting

The duct hose, which will be flexible, will attach to the box. This needs to be run through your attic space to the nearest soffit for the roof. Using the jab saw and the template which came with the duct kit, cut a hole of the correct size in the soffit. Depending on the ease of access, you might need to do this from the outside.

Screw the outside vent around the hole to the outside of the soffit, then attach the duct hose to the outside vent. As this vent faces downward, rain and snow cannot enter the vent.

Step 4 - Wiring the Fan

Turn off the house electricity at the breaker box. Fit the extractor fan into the box following the manufacturer’s instructions. In the attic, locate the junction box that supplies the bathroom light and open it. Use wire strippers and wire nuts to connect wire from the extractor fan. Run the wire to the junction box and connect. Use red wire for live, black for neutral and green for earth.

Always check you’ve made the correct connections before tightening the screws on the terminals. Put the cover back on the junction box and turn the electricity back on. Using the pull cord on the extractor fan, switch it on to ensure it works properly. Switch the fan off again.

Step 5 - Finishing

To complete the job, you will need to install the extractor fan cover the in the bathroom and, finally, the frame. Screw both of these in place and your extractor fan is installed.