Need a new Exhaust Fan?

What is the purpose of an exhaust fan?

Exhaust fans serve the purpose of eliminating or reducing odours, in most cases being the toilet, and they also remove condensation from cooking, tumble dryers, showers and baths. Where there is no natural ventilation to outside, the Building Code of Australia (BCA) requires mechanical ventilation in the form of an exhaust fan.

bathroom-fan-diagram2Where do I need to have an exhaust fan?

Exhaust fans have different uses. If there is a chance of condensation forming or odours prevailing then it’s a very wise decision and in most cases mandatory to have a fan installed in the required room(s). In the kitchen, most houses have a range hood to reduce steam and dangerous gases from cooking. Boiling water for example produces steam, which then turns into water that may cause condensation on walls, ceilings and around windows.  When this happens, an excess build-up of mould and mildew can form and if not properly ventilated it can be harmful to the health of the occupants. Condensation can be a costly problem structurally, seeping into cracks and causing rot to form – as they say prevention is better than cure. Bathrooms and laundries also need adequate ventilation. Tumbler dryers that aren’t vented to outside and having hot showers can produce a large amount of condensation. For an exhaust fan to be effective it needs to be able to expel the humidity in the air from the room it’s in. To work out the size of fan that’s required for a particular room, you need to calculate the volume of the room – L x W x H and then multiply the number of air changes required per hour. A well ventilated home or office could be less costly to heat, as well as being a healthier place to live and work in.


An often ignored or misunderstood compliance issue with toilet and bathroom ventilation for residential and accommodation premises is the BCA (Building Code of Australia) requirement relating to discharge of exhaust air into the atmosphere. To put it simply, if you have a colourbond, flat or narrow pitched roof or sarking (silver paper insulation) in your ceiling space then you will need to have a ‘ducted’ exhaust unit installed. The lower level of a two story house will also need to have either ducted fans installed, or if suitable a wall fan, but this will be dependent on the design of the house and what it allows for structurally. Exhaust fans are not required to be directly ventilated outside where the roof space contains open eaves, roof vents, including a vented ridge or a tiled roof without sarking. The recommended air flow rate of exhaust fans state they should be between 50 – 100L/s.

Who can install an exhaust fan?

A qualified electrician will need to install any exhaust systems into your home or office. You will need to ensure that the unit and its installation comply with Australian Standard (AS) 3666.1 ‘Air handling and water systems of building – Microbial control’. This will dictate the required flow rate and noise level. It also needs to comply with AS 1668.2 ‘Mechanical ventilation for acceptable indoor air quality’.

How much does an exhaust fan cost?

The cost of vans vary on the size, quality and power of the mechanism through to the installation requirements – Is it against a wall for ventilation, going directly outside or is it going into a roof’s ceiling space? Electricians can provide a range of fans suitable for residential properties right through to large scale requirements for industrial sites.  A wall mounted unit may set you back $500, where as a standard duct into your roof space will only cost between $30 and $40. If you require ‘ducted’ exhaust units to be installed – ducting extracts directly into the atmosphere, then this will cost anywhere between $350 and $600 per unit and that’s just supplied, not installed. Be wary when you’re designing and building a new home, as the way in which your roof is designed (flat/tin/pitched) and if you have sarking in your ceiling space, along with the number of bathrooms you have can greatly increase the overall cost of the exhaust fans and the type that will be required – depending on the volume of air.

Dirty exhaust fan?

What’s the best way to clean an exhaust fan? Giving the fascia of an exhaust fan a good go over with the vacuum cleaner will usually take most of the excess dirt and dust away, however if you want to give it a really good clean then you’ll need to remove the exhaust fan’s fascia (make sure you do this in a safe manner) and wash it thoroughly with warm soapy water, then air dry it. Once dry, you can replace the cover.

Want to know more?
Building Code of Australia (BCA) Ventilation Requirements, what the law states…  Click here for more information.


Prolux Electrical Contractors provide installation of exhaust fans for all areas that require added ventilation, including kitchens, bathrooms and toilets. We abide by all OH&S regulations and follow the BCA’s ventilation requirements.

Call Prolux Electrical Contractors on 1800 800 880

3/52 Corporate Boulevard, Bayswater VIC 3153