Exhaust fans are the most overlooked ventilation system in a Melbourne home — until the bathroom ceiling grows mould, the paint starts peeling, or the room never seems to dry out through a damp Melbourne winter. A correctly sized and correctly ducted exhaust fan removes the warm, moisture-laden air from bathrooms, laundries and kitchens and discharges it outside, protecting the building fabric and the health of the people inside it. This guide covers how exhaust fans work, what installation and repair cost in Melbourne in 2025, the ventilation regulations that apply, and how to stop the condensation and mould problems that affect so many Melbourne homes.
From $250Complete supply and install of a replacement exhaust fan in Melbourne (minimum call-out)
25 L/sMinimum bathroom exhaust airflow under AS 1668.2 for Melbourne homes
Vent OutsideExhaust must discharge to outdoor air — never into the roof cavity
Why Exhaust Fan Ventilation Matters in Melbourne Homes
Melbourne’s climate makes bathroom and laundry ventilation more important than many homeowners realise. Through the long, cool, damp winter from May to September, the air outside is humid and the building stays cold — so the moisture produced by a hot shower has nowhere to go. Without effective extraction, that moisture condenses on the coldest surfaces in the room: the ceiling, the window reveals, the grout, and the corners. Repeated daily, this is exactly the condition mould needs to establish and spread.
The consequences are not just cosmetic. Persistent moisture in a Melbourne bathroom leads to peeling paint, swollen and delaminating plasterboard, rusting fixings, and mould that can affect respiratory health — a particular concern for households with asthma or allergies, which are common across Melbourne. In the roof cavity, an exhaust fan that vents into the roof space rather than outside causes condensation on the roof timbers and the underside of the roof sheeting, leading over time to timber rot, rusted brackets, and ruined ceiling insulation.
A properly specified exhaust fan system solves all of this by doing one simple thing reliably: moving the moist air out of the building before it can condense. Getting there requires the right fan capacity for the room, a duct that actually carries the air outside, and a fan that is kept clean enough to deliver its rated airflow. The topics below cover each part of the picture.
The Most Common Melbourne Installation Fault The single most common exhaust fan fault found in Melbourne homes is a fan that discharges into the roof cavity instead of outside. It looks like it is working — the fan runs and air leaves the room — but the moisture is simply being relocated into the roof space, where it does serious and expensive damage. If your fan has no visible roof cowl or eave vent serving it, have it checked.
Frequently Asked Questions — Melbourne Exhaust Fans
How much does it cost to install an exhaust fan in Melbourne?
A like-for-like exhaust fan replacement in Melbourne — where wiring and ducting already exist — starts from $250 as a complete supply-and-install job, and is typically $280 to $480 depending on the fan chosen. A new exhaust fan installation that requires new wiring, cutting in a new ceiling or wall location, and ducting the discharge out to the roof or eave is more involved — generally $550 to $1,200 as a complete job. Kitchen rangehood installation with ducting to the outside is higher again. No qualified Melbourne tradesperson attends a job for under $250, so the minimum call-out applies even to the smallest replacement. All FreshDuct pricing is complete-job pricing — you see the full installed price, not a parts list. Call 0431 918 137 for a site-specific quote.
Does an exhaust fan have to vent outside in Melbourne?
Yes — a bathroom or laundry exhaust fan should discharge to the outside (through the roof or an eave), not simply dump moist air into the roof cavity. Venting into the roof space is one of the most common installation faults found in Melbourne homes, and it causes serious problems: the warm, moisture-laden air condenses on the cold underside of the roof and on roof timbers, leading to mould, rot, rusting of metal fixings, and degraded ceiling insulation. The National Construction Code and AS 1668.2 require mechanical exhaust from wet areas to discharge to outdoor air. See our
guide to venting an exhaust fan to the roof for how it should be done.
Why does my Melbourne bathroom still get mould even though it has an exhaust fan?
There are several common reasons a Melbourne bathroom grows mould despite having an exhaust fan: (1) the fan is undersized for the room and cannot move enough air — AS 1668.2 sets a minimum of 25 litres per second for a bathroom; (2) the fan is not ducted to the outside and is recirculating moist air into the roof cavity; (3) the fan is not run long enough — it needs to run during the shower and for at least 15 to 20 minutes afterwards; (4) the fan motor or impeller is clogged with dust and lint, reducing its actual airflow well below its rating; or (5) Melbourne’s cool, damp winter air means the bathroom simply does not dry out between uses. See our
condensation and mould guide for the full diagnosis and fixes.
What size exhaust fan do I need for a Melbourne bathroom?
Exhaust fans are rated by airflow in litres per second (L/s) or cubic metres per hour. AS 1668.2 sets a minimum mechanical exhaust rate of 25 L/s for a bathroom and 40 L/s for a kitchen in a Melbourne home. As a practical rule, the fan should be able to change the air in the room around 8 to 10 times per hour — so a larger bathroom or one with a separate shower enclosure needs a higher-capacity fan than the 25 L/s minimum. Ceiling height, the length and number of bends in the duct run, and whether the room has an openable window all affect the real-world performance. See our
ventilation regulations guide for the Melbourne requirements.
Can I install an exhaust fan myself in Melbourne?
Replacing the cover or cleaning the fan is something Melbourne homeowners can safely do. However, installing a new exhaust fan, replacing the motor, or any work involving the 240V wiring must be carried out by a licensed electrician — it is illegal in Victoria for an unlicensed person to do fixed electrical wiring, and doing so voids home insurance. Ducting the fan to the roof also needs to be done correctly to avoid condensation and mould problems in the roof cavity. FreshDuct provides licensed exhaust fan supply, installation, repair and ducting across Melbourne. Call 0431 918 137 for a quote.
