Floor waste alert

Floor waste gully requirements and standards are split between the National Construction Code (NCC) and The Australian Standards (AS/NZS 3500.2 2021).

Let’s start with when it is a requirement under the NCC to install a floor waste gully. NCC states that in a Class 2 or 3 building, or Class 4 part of a building, a bathroom or laundry located at any level above a sole-occupancy unit or public space must have a floor waste gully.

Class 2 buildings are apartment buildings. They are typically multi-unit residential buildings where people live above and below each other. The NCC describes the space as an apartment/sole-occupancy unit. Class 2 buildings may also be single-story, attached dwellings with a common space below.

For example, two dwellings above a common basement or car park.

Class 3 applies to residential buildings other than Class 1 (stand alone houses) or Class 2 buildings, or a Class 4 part of a building. Class 3 buildings are a common place of long term or transient living for a number of unrelated people. Examples include a boarding house, guest house, hostel or backpackers (that are larger than the limits for a Class 1b building). Class 3 buildings could also include dormitory-style accommodation, or workers’ quarters for shearers or fruit pickers. Class 3 buildings may also be ‘care-type’ facilities such as accommodation buildings for children, the elderly, or people with disabilities, which are not Class 9 buildings.

A Class 4 part of a building is a sole dwelling or residence within a building of a non-residential nature.

An example of a Class 4 part of a building would be a caretaker’s residence in a storage facility.

A Class 4 part of a building can only be located in a Class 5 to 9 building.

Now, let’s have a technical look into floor waste gullies.

Where a floor waste is installed, the minimum continuous fall of a floor plane to the waste must be 1:80, and the maximum continuous fall of a floor plane to the waste must be 1:50. Floor waste gullies should be installed with an accessible removable grate and have a riser of not less than DN 80 to the finished surface level. Where the sole function of the floor waste gully is to dispose of water spillage and wash-down water, a minimum DN 50 riser may be used as per AS/NZS 3500.2 2021. Floor waste gullies should not be installed in any refrigerated cool room, air conditioning return air plenum or similar structure.

Do you need a floor waste when installing a urinal?

When one or more wall-hung urinal is installed, a floor waste gully must be installed in the same room and the floor must be graded towards the gully. If you have a floor- or slab-type urinal you do not require a floor waste gully, regardless of whether it has a step or not, unless the specific building requires one.

If you find a floor waste gully drawn on plans, when you know, from the information above, that it is not required, make sure you discuss this with the builder before you make a final decision. The builder may have other requirements outside the regulations and standards that mean a floor waste gully is a wise decision.