How much does it cost to install a bathroom extractor fan in NZ?

Installing a bathroom extractor fan in New Zealand usually costs about $650–1,250 all-in for a ducted 150mm fan vented outside: the fan is $185–265 at Mitre 10 or Bunnings, and an Auckland electrician publishes $400–900 + GST as its average installation, taking 1–3 hours (Endeavour Property Services). Swapping a fan like for like needs no building consent. It must vent outside, never into the roof space.

How much does a bathroom extractor fan cost to buy?

Every fan in the table clears the minimum comfortably, because a 150mm fan meets the 120mm diameter rule on its own and each one moves far more than 25 litres per second. The extra money buys quietness, an inline motor in the ceiling space rather than above your head, or a heater and light in the same fitting. Prices change, so check on the day.

How much does an electrician charge to install an extractor fan?

Endeavour Property Services, an Auckland electrical firm, publishes $400–900 + GST as its average extractor fan installation, which is $460–1,035 including GST, and says most take 1–3 hours. It puts the difference down to the type of fan and how complex the installation is. Its page does not say whether the fan is included, so in the worked example below we price the fan on top, to be safe. The cheap end is a like-for-like swap on an existing duct; the expensive end is a new duct run through the ceiling space to a soffit or roof vent, or a new switched circuit.

What size extractor fan does a bathroom need in NZ?

At least 25 litres per second. Tenancy Services says that in any room with a shower or bath, a fan installed after 1 July 2019 must have a minimum diameter of 120mm including its ducting, or an exhaust capacity of at least 25 litres per second, and it must ventilate to the outside. The Building Code's Acceptable Solution G4/AS1 uses the same 25 L/s for a bathroom fan that runs intermittently, and 10 L/s for one that runs continuously (BRANZ Level). Those are minimums for the installed system, not the fan on the box: a long duct with bends cuts the real flow, which is why a 150mm fan rated at 100 L/s is the usual choice.

Can a bathroom fan vent into the roof space?

No. BRANZ's Level guidance is blunt: air extraction systems must not vent into a ceiling or roof space. Steam dumped there condenses on the underside of the roof and the framing, and Tenancy Services requires every bathroom fan in a rental, old or new, to ventilate to the outside of the house. Recirculating units, and HRV or DVS-type systems that move air around the house, do not count as extraction. If you lift the ceiling hatch and find the fan's duct lying loose in the insulation, the fix is a duct to a soffit, wall or roof vent, not a new fan.

Do you need an electrician to install a bathroom fan?

In practice, yes. WorkSafe allows homeowners to do a short list of their own electrical work under strict conditions, but it does not recommend it without the skills, and wiring in a bathroom is where the risk is highest. A registered electrician wires the fan in and gives you a certificate of compliance for the work; the EWRB sets out what documentation you should get. Keep it with the fan's make, model, duct diameter and flow rate. Our guide to who has to be licensed covers how to check the register.

A worked example: fixing a rental's fan before a healthy homes check

A 1980s Wellington rental. The bathroom fan works, but the landlord finds its duct ends in the roof space, so it does not ventilate outside and fails the standard. The ceiling is accessible and the eaves are a short run away.

Had the old fan already vented outside through a working duct, and only the motor died, the job would sit at the low end: the fan, an hour's labour and a call-out. The landlord should ask for the fan's diameter, ducting and flow rate in writing, which is exactly what Tenancy Services advises, because a tenant can ask for healthy homes compliance information. The rest of the rental rules are in renovating a rental bathroom.

Does installing an extractor fan need building consent?

Not to replace one like for like. Schedule 1 clause 1 of the Building Act exempts the repair, maintenance and replacement of a building component with a comparable one in the same position. A brand-new hole through the cladding or roof for a new duct is building work too; it is usually minor, but if you are unsure, ask your council before anyone cuts. Exempt or not, the work still has to comply with the Building Code. Where the fan is part of a bigger renovation that does need consent, such as adding a bathroom, it goes on the same plans. Our bathroom consent guide sets out what does and does not need a consent.

Fitting the fan as part of a bathroom renovation

A renovation is the cheapest moment to get the fan right, because the ceiling is open and the duct can go wherever it needs to. The fan becomes a small line in the electrical budget rather than a separate call-out. Our bathroom renovation cost guide shows where the money goes, and the measure-and-design visit records the existing fan, its duct size and where it vents, so the budget shows whether it is already compliant.