Short answer: A bathroom exhaust fan should be ducted to the outside (not just into the roof space), sized for the room, and positioned away from the shower’s wettest zones as required by the wiring rules. Heat lamps and 3-in-1 units (fan, light and heat) need more power and careful switching. All installation and wiring is work for a licensed electrician, who must follow the bathroom zone rules in AS/NZS 3000.
Bathrooms in Inner West terraces and older apartments are often small, with no window or a tiny one, and mould on the ceiling. A properly installed exhaust fan is one of the best fixes. Add a heat lamp or a 3-in-1 unit and winter mornings get a lot more comfortable. Here’s what to consider.
Fan types
Ceiling exhaust fan
The most common type. It sits in the ceiling and pulls moist air up into a duct. The duct should run to the outside through an eave, wall or roof vent.
Wall exhaust fan
Fitted in an external wall, venting straight outside. Ideal where there’s no roof space, such as some terrace extensions or ground-floor units with a slab above.
Inline fan
The motor sits in the roof space and ducts connect to a ceiling grille. It’s quieter in the bathroom and often more powerful, good for larger or ensuite bathrooms.
3-in-1 units
Combine an exhaust fan, a light and heat lamps (or a fan heater) in one ceiling unit. They save ceiling space but need careful switching so the heat isn’t left on.
Duct it outside
Venting a fan into the roof space just moves the moisture somewhere you can’t see it. That can lead to mould, rotting timber and damp insulation. Run the duct to an eave or roof vent. In homes with no roof space, a wall fan or a short duct to an outside wall is the usual answer. Your electrician or ventilation installer can advise on the duct route.
Sizing
Fans are rated by how much air they move. Bigger bathrooms, long duct runs and bends all mean you need more capacity. Look at:
- the room size
- the duct length and number of bends
- noise levels, usually given in decibels or sones
- whether it has a backdraft shutter to stop cold air coming back in
Heat lamps and heaters
| Option | Pros | Cons |
|---|---|---|
| Heat lamps (in a 3-in-1 or separate) | Instant warmth on skin | Bright, hot globes; higher power draw |
| Fan heater units | Warm the air more evenly | Slower to warm you, can be noisier |
| Heated towel rail | Dries towels, some ambient heat | Not enough to heat the room |
| Underfloor heating | Comfortable, invisible | Best installed during a renovation |
Heaters and heat lamps draw more power than an exhaust fan. Your electrician will check that the circuit can handle the load, and may recommend a separate circuit or a timer switch.
Wet area zones
The wiring rules (AS/NZS 3000) set zones around showers and baths that limit what electrical equipment can go where, and what water protection it must have. In practice that affects:
- where fans, heat lamps and lights can be mounted
- where switches and power points can go
- what IP rating fittings need
The exact distances depend on the layout, including shower screens and ceiling height, so leave the final positions to your electrician. Don’t fit or move bathroom electrics yourself.
Switching options
- Separate switches for light, fan and heat, so you can run the fan without the heat
- Fan run-on timer, so it keeps running for a set time after you leave
- Humidity sensor, which turns the fan on automatically
- Heat lamp timer, which stops heat lamps being left on all day
Steamy bathroom or freezing winter showers? We install exhaust fans, heat lamps and 3-in-1 units across the Inner West, ducted properly outside. Call 0421 772 661 or see our indoor lighting service.
Safety switches
All new bathroom circuits should be protected by a safety switch. If your home has old ceramic fuses or limited RCD protection, see safety switch rules in NSW. Wet areas are exactly where shock protection matters most, as the NSW Government recommends.
Renovating the whole bathroom?
Plan the fan, lighting, heating and power points before tiling. Combine it with a switchboard check if you’re adding new circuits. For other rooms, see kitchen renovation electrical planning.
We install bathroom fans and heaters in Croydon Park, Hurlstone Park, Enmore and nearby suburbs.
Frequently asked questions
Can a bathroom exhaust fan vent into the roof?
It’s not recommended. Venting into the roof space can cause moisture, mould and damage. Duct it to the outside through an eave, wall or roof vent.
Do bathroom heat lamps need their own circuit?
Not always, but heat lamps and heaters draw more power than a fan, so your electrician will check the circuit capacity and may recommend a dedicated circuit or timer.
Can I install a bathroom exhaust fan myself?
Not the electrical part. Wiring a fan in NSW is electrical work that needs a licensed electrician, and bathroom zone rules apply.
What’s a 3-in-1 bathroom unit?
A ceiling unit that combines an exhaust fan, a light and heat lamps or a heater. Separate switching and a timer are recommended.