Bathroom Exhaust & Extraction Fans (Wet Areas) Guide

Bathroom ventilation fixes condensation by removing moisture from the air before it has a chance to settle on cold surfaces. When humid air generated by showers is actively extracted and expelled outside, overall humidity levels in the bathroom drop quickly. With less moisture in the air, warm air is far less likely to reach its dew point when it contacts cooler walls, ceilings, mirrors, and tiles. By lowering humidity at the source and maintaining continuous air movement, effective bathroom ventilation prevents water vapour from turning into liquid condensation, keeping surfaces dry and significantly reducing the conditions that lead to mould, mildew, and moisture damage.

Bathroom ventilation prevents mould and mildew by removing the moisture they rely on to grow. Mould and mildew thrive in warm, damp, poorly ventilated environments where humidity remains high for extended periods. When moisture-laden air from showers is not extracted, it settles on surfaces and keeps walls, ceilings, grout, and sealants damp — creating ideal conditions for mould to establish and spread.

Effective bathroom ventilation continuously lowers humidity levels by extracting moist air at the source and expelling it outside. This keeps surfaces drier, shortens drying times after showering, and breaks the moisture cycle that allows mould and mildew to form. By preventing persistent dampness rather than treating visible growth after it appears, proper bathroom ventilation provides a long-term solution to mould and mildew problems and helps maintain a healthier indoor environment.

Bathroom ventilation eliminates musty and stale odours by removing the damp, stagnant air that causes them. These smells develop when moisture becomes trapped in a bathroom, allowing bacteria, mould spores, and organic matter to break down and release unpleasant odours. Over time, the air itself becomes stale, lingering long after showering and often spreading into adjoining rooms.

Effective bathroom ventilation actively extracts this moisture-laden, stale air and replaces it with drier, fresher air, preventing odours from forming in the first place. By reducing humidity levels and keeping surfaces dry, proper ventilation removes the source of musty and stale smells, resulting in a fresher, healthier bathroom and improved air quality throughout the home.

Bathroom ventilation helps prevent damp damage to paint, plaster, and cabinetry by controlling humidity levels before moisture can soak into building materials. When humid air is allowed to linger, moisture is absorbed into painted surfaces, plasterboard, and joinery, leading to peeling paint, bubbling finishes, swollen cabinetry, and deteriorating sealants.

By actively removing moisture at the source, effective bathroom ventilation shortens drying times and keeps surfaces dry after showering. This prevents repeated wetting cycles that cause materials to break down over time, preserving finishes, extending the life of cabinetry, and maintaining the overall condition of the bathroom and surrounding spaces.

Bathroom ventilation prevents moisture migration into roof and wall cavities by removing humid air before it can escape beyond the bathroom itself. Warm, moisture-laden air naturally rises and seeks paths of least resistance, moving through gaps around light fittings, exhaust penetrations, wall cavities, and ceiling spaces. Without proper extraction, this moisture can accumulate out of sight, leading to hidden mould growth, damp insulation, timber decay, and long-term structural damage.

Effective bathroom ventilation captures and expels moist air directly to the outside, stopping it from entering roof and wall cavities in the first place. By controlling moisture at the source, ventilation protects not only the bathroom, but the wider building envelope and the long-term health of the home.

Fan placement is critical to effective bathroom ventilation. Even a powerful fan will perform poorly if it is installed in the wrong location.

Best practice is to position the intake:

• Directly above or as close as possible to the shower or bath, where moisture is generated
• At the source of steam, rather than simply centred in the room
• Away from doorways, which can short-circuit airflow and reduce extraction effectiveness

Short, straight duct runs to the exterior significantly improve performance by reducing resistance and allowing the fan to operate more efficiently.

Using an inline exhaust fan offers major advantages over a typical ceiling-mounted fan. With inline systems, the electrical components are housed at the fan unit itself — not at the ceiling grille — which allows the intake grille to be installed much closer to wet areas. This makes inline fans particularly well suited to modern bathrooms and walk-in showers.

For enclosed showers, we recommend installing the intake grille directly above the shower head, within the shower space. This captures steam immediately as it forms, preventing it from escaping into the rest of the bathroom.

With walk-in showers, placement is more challenging due to the open design. In most cases, the best results are achieved by installing the intake grille above the shower entrance, where rising steam exits the shower zone and can be captured before spreading throughout the room.

Moisture remains in the air after showering stops.

Fans should:

• Start before showering
• Run during showering
• Continue operating for 10–30 minutes afterward

Timers and automatic controls ensure moisture is fully removed and prevent delayed condensation.

Moist air does not stay confined to the bathroom. It migrates through:

• Ceiling cavities
• Wall cavities
• Adjacent rooms

Poor bathroom ventilation can contribute to mould and damp issues elsewhere in the home. Effective extraction protects the entire building envelope.

3-in-1 fan/light/heat units are popular, but in practice they come with a long list of compromises that make them a poor choice for effective bathroom ventilation.

Firstly, the heat lamps themselves present a genuine fire risk. They run at very high temperatures and, over time, accumulate dust and lint — which makes them dust magnets and further increases the risk of overheating or fire.

They also require a large cut-out into the ceiling, creating a significant opening into the roof space. This allows dust, insulation fibres, odours, and other contaminants from the roof cavity to migrate back into the bathroom and living space.

From a ventilation perspective, their performance is fundamentally flawed. Most 3-in-1 units cannot be ducted to the outside, meaning moist air is discharged straight into the roof space, where it can cause condensation, mould growth, timber decay, and corrosion. Even when ducting is technically possible, it is not advisable — the fans used in these units are low-pressure axial fans and are simply not powerful enough to push air through ducting. As soon as ducting is added, the real airflow drops dramatically compared to the advertised figures.

Because these fans have very poor pressure capability, something as simple as closing the bathroom door can substantially reduce airflow. They also cannot be installed directly over the shower, which means steam is allowed to spread throughout the bathroom before any extraction occurs.

On top of all this, 3-in-1 units are typically noisy, yet still deliver low airflow, making them both uncomfortable to use and ineffective at controlling moisture.

In short, 3-in-1 fan/light/heat units try to do too many jobs at once — and do none of them particularly well. For reliable moisture control, quieter operation, and long-term durability, a properly designed and ducted exhaust system with a dedicated ventilation fan is a far superior solution.

Decibel ratings are often misunderstood and, in many cases, misused. On their own, dB figures rarely reflect how loud a fan will actually sound once installed in a real building. Unfortunately, some manufacturers take advantage of this by publishing selectively measured or unrealistic noise figures that do not represent real-world performance. Some manufacturers are simply dishonest. Please see our Instagram post HERE and our Instagram video HERE for a good explanation of the issue.

Firstly, decibel ratings are typically measured under laboratory conditions that bear little resemblance to an installed environment. Measurements may be taken at unrealistic distances, at reduced fan speeds, without ducting attached, or in free-air test rigs. This makes it very easy to publish an impressive number that does not translate to real installations in homes.

Secondly, not all noise is perceived equally. The frequency of the sound (its pitch) is often far more important than the overall decibel level. Many fans with low published dB ratings produce a noticeable high-frequency motor “whine”. This type of noise travels easily through building materials and is particularly intrusive to occupants. By contrast, our centrifugal fans predominantly generate airflow noise rather than motor noise. Once installed, airflow noise is largely attenuated by ducting on either side of the fan, while motor whine continues to transmit through structures.

Thirdly, decibel scales are logarithmic, not linear. A small numerical difference in dB can represent a significant perceived difference in loudness, yet manufacturers often quote figures without context or explanation. This makes side-by-side comparisons meaningless unless the test methods are identical and independently verified.

We have been installing bathroom ventilation systems for over 15 years and have tested virtually every fan available on the market, including all major competing models. Based on extensive real-world installation experience, we are confident that our fans are quieter in installed conditions than any comparable models currently available.

Importantly, our decibel ratings have been independently tested in Australia by VIPAC Engineers & Scientists Ltd, providing credible, third-party verification rather than marketing-driven claims.

For a clear visual explanation of why published noise figures can be misleading, we recommend viewing our Instagram videos linked above, which break this issue down in simple, practical terms.

In summary, decibel ratings alone do not tell the full story. Installation method, operating speed, sound frequency, fan design, ducting, and vibration isolation all have a greater impact on perceived noise than a single dB number. This is why real-world performance and proven installation experience matter far more than headline specifications.