Martec Exhaust Fans and Bathroom Heating

Exhaust fan size is determined by airflow capacity, measured in litres per second (L/s) or cubic metres per hour (m³/hr). As a general guide, the Australian Standard AS 1668.2 recommends a minimum of 25L/s for bathrooms and 40L/s for larger ensuites with a shower and bath. To calculate the right size for your space, multiply the room's length, width and height, then match this to the fan's rated capacity, as a rule of thumb, look for a fan that can achieve 15–20 air changes per hour.

Yes. Exhaust fans involve electrical wiring and, in many cases, ducting through ceiling or wall cavities, so installation must be carried out by a licensed electrician to comply with AS/NZS 3000 (Australian Wiring Rules). If your fan is being installed in a bathroom, it will also need to meet the IP rating requirements for the relevant water exposure zone. Engaging a licensed professional ensures your installation is safe, compliant, and won't affect your home insurance or building certification.

Exhaust fans should always be ducted to the outside of your home, whether through the roof, eave or external wall, rather than exhausting directly into the roof cavity. Venting into the roof space allows moisture and humid air to accumulate, which can lead to condensation, mould and long-term timber or insulation damage. Proper external ducting is a requirement under the National Construction Code and is essential for protecting your home's structure over time.