Which bathroom extractor fan should I choose? Why fans are necessary

Mould is never a welcome sight in your bathroom. Not only is it unsightly, but its presence in living spaces is also associated with a range of dermatological and respiratory conditions and responsible for a decrease in our overall quality of health and wellbeing.

The optimum conditions for mould are warm and moist spaces out of direct sunlight, such as bathrooms, which are the areas most prone to mould growth in modern houses. The problem is exaggerated if your bathroom has limited - or no - natural light as mould thrives in areas with low lighting.

While it might not always be possible to increase the natural light or decrease the warmth of your bathroom, there is thankfully an easy way in which you can tackle damp, preventing mould growth.

Bathroom extractor fans are designed to reduce the humidity of your bathroom, pulling out condensation as well as any mould spores that might be lurking.

Which bathroom extractor fan should I choose? Fan type

There are three types of bathroom extractor fan to choose from:

1. Axial extractor fans - the least powerful type of fan, axial extractor fans can only be installed on an outside wall and should not be ducted more than 2m
2. Centrifugal extractor fans - more powerful and noisier than axial fans, these do not need to be placed on a wall with access to the outside and can be ducted further than an axial extractor fan
3. Inline extractor fans - the most powerful type of extractor fan, these are installed in the loft and can be ducted large distances (more than 50m). Due to being installed in a ceiling void or loft space, the noise they make is rarely heard

The extractor fan you choose is dependent on the size of your bathroom and how far you need to duct the airflow. The more powerful the extractor fan, the more expensive it will be.

Which bathroom extractor fan should I choose? Power

When choosing an extractor fan for your bathroom, take into consideration the dimensions of the space. In order to guarantee optimum results, you need a fan that executes a complete air change in your bathroom at least four - and ideally eight - times per hour.

The power of an extractor fan is measured in cubic feet per minute (CFM). Extractor fans are sold in ratings of anywhere between 50 and 110 CFM.

This means that a bathroom of 50 square feet requires an extractor fan rated at 50 CFM at least. If your bathroom measures less than 50 square feet, it is usually better to opt for a 50 CFM fan rather than searching for something smaller.

If your bathroom measures more than 110 square feet, you should install multiple extractor fans around the bathroom or consider a more powerful fan type.

Of course even among bathrooms of a similar dimension, requirements vary. If your bathroom is extremely well-ventilated with plenty of natural light, it is not necessary to choose an extractor fan with a CFM higher than the dimensions of your bathroom. If you have no natural light, it is advisable to choose a more powerful extractor fan in order to prevent mould.