Building Code of Australia (BCA) Ventilation Requirements

Ventilation Requirements for Australia

When planning a ventilation system, there are a few building code requirements that you need to be aware of. In particular, the Building Code of Australia (BCA) states that you must have windows that are equal in size to at least 10% of the floor space, for the purpose of natural light – or 3%, for roof lights (or a proportional combination of windows and roof lights).

If a window is installed in a room, then it becomes the primary source of ventilation for the room. Therefore, irrespective of whether an exhaust fan is installed, if the room in question has a window installed in accordance with the provisions of sub-clause (a) then the ventilation requirements for the room complies with the BCA.

If the room has ventilation borrowed from an adjoining room in accordance with sub-clause (b) it also complies with the BCA.

If an exhaust fan is installed, it only needs to comply with sub-clause (c) if it is the only source of ventilation to the room. Therefore in accordance with sub-clause (c):
•    open eaves;
•    roof vents, including a vented ridge;
•    a tiled roof without sarking.

Bathroom Ventilation Requirements

The regulations require a fan capable of a minimum extraction capacity of 25 litres per second when installed.

Toilet Ventilation Requirements

The regulations require a fan capable of a minimum extraction capacity of 25 litres per second when installed.

Kitchen Ventilation Requirements

The regulations require a fan capable of a minimum extraction capacity of 50 litres per second when installed.

Laundry Ventilation Requirements

The regulations require a fan capable of a minimum extraction capacity of 20 litres per second when installed.

The 5% Ventilation Requirement

For the purpose of ventilation, an openable window or similar aperture is required to be at least 5% of the floor space in that particular area. The area itself may be defined just as one particular room, or a combined set of adjoining spaces. Also, in a room where there is no ceiling fan, the BCA states that you must achieve effective cross ventilation.