NCC 2022 – Condensation management

From October 1^st 2023 there were significant changes to condensation management requirements for Class 1a dwellings.

The main changes from the previous NCC version include:

     * All exhaust fans must now be ducted externally and not into the roof space. Previously exhausts could be discharged into a roof space if it was adequately ventilated

     * A kitchen rangehood must be ducted externally, and cannot be a recirculating system (i.e. blowing air back into the room)

     * A venting clothes dryer must be ducted externally. This doesn’t apply to other types of dryers such as condensing systems

     * A bathroom or sanitary compartment which does not have compliant natural ventilation (i.e. having no window, or the openable area of the window is less than 5% of the area of the room) must have an exhaust fan which is interlocked with the room’s light switch. The light switch must include a run-on timer so that the exhaust continues to run for 10 minutes after the switch is turned off

    * Any room which does not have sufficient natural ventilation (i.e. having no window, or the openable area of the window is less than 5% of the area of the room) must be provided with make-up air. There are two ways to comply:

    * Via openings to an adjacent room with a free area of 14,000mm²; or

    * In accordance with AS1668.2

The opening is simply a gap underneath the door which is calculated by 14,000 divided by the width of the door.

e.g. 14000 / 820mm door = 17.07mm, rounded up to 18mm

Other examples are:

    * 720 door = 20mm gap

    * 770 door = 19mm gap

    * 820mm door = 18mm gap

    * 870mm door = 17mm gap

Alternatively if a gap is not provided under the door then a recirculating air system is required to be designed to AS1668.2. Note: this is not a ducted air conditioning system and would need to be designed by a mechanical engineer

    * There are new requirements to ventilate roof spaces in Climate Zones 6, 7 and 8. This does not apply to any part of Queensland, and mostly applies to Victoria and part of New South Wales.