| To | Licensees / Contractors / the Plumbing and Drainage Industry |
| From | Building Construction Compliance, Plumbing Team, Parramatta |
| Date | June 2023 |
| Scope | Applies to all metropolitan and regional areas in New South Wales. |
Issue
With the adoption of the National Construction Code (NCC) 2022 on the 1st May 2023, NSW Fair Trading is reminding the plumbing and drainage and building industry of the following requirements when installing floor waste gullies and baths.
The NCC 2022 prescribes the Performance and Deemed-to-Satisfy requirements for Wet area applications and sanitary plumbing and drainage systems.
Floor waste gully requirements
NCC 2022 Volumes 1 & 2 - Building Codes of Australia 2022
Floor wastes are required to be installed in certain wet area applications, and the falls required across a floor surface are prescribed in:
- Building Code of Australia (BCA) Class 2 to 9 buildings Part F2 – Wet Areas and overflow protection
- Building Code of Australia (BCA) Class 1 and 10 buildings Part H4 – Health and Amenity.
NCC Volume 3 - Plumbing Code of Australia 2022
Part C1 Sanitary plumbing systems - Clause C1D2 Invert levels
The invert level of a trap or gully weir must be a minimum of 10mm higher than the soffit of the pipe to which it connects.
Part C2 Sanitary drainage systems - Clause C2D2 Invert levels
The invert level of a trap or gully weir must be a minimum of 10mm higher than the soffit of the pipe to which it connects.
AS/NZS 3500.0:2021 – Plumbing and Drainage Glossary of terms
3G.19: Grate – sanitary or stormwater fitting consisting of a frame holding a grating
3G.19: Grating – framework of parallel or crossed bars or plate having holes or slots to prevent ingress of large solids
3G.28.2: floor waste gully FWG – gully installed inside a building for use with a floor waste grating or waste outlet fitting on a riser pipe and with provision for connection of waste pipes for fixtures
AS/NZS 3500.2:2021 – Sanitary Plumbing and Drainage
Clauses 4.6.7.6 – Removable grate
Floor waste gullies (FWG) shall be installed with an accessible removable grate and have a riser of not less than DN 80 to finished surface level. Where the sole function of the FWG is to dispose of water spillage and wash-down water, a minimum DN 50 riser may be used.
Clauses 4.6.7.7 – Height of gully riser
The height of the gully riser shall be measured from the top of the water seal to the floor surface level and conform to the following:
(a) For floor waste gullies with connections to the gully riser –
(b) The minimum height shall comply to Table 4.6.7.7; and
(c) The maximum height shall be 600mm.
(d) For floor waste gullies with submerged inlets, the minimum height shall be 100mm
Note: The maximum height may be extended to 1m when receiving the discharges from plant rooms located above ground floor level.
Sizing of floor wastes for:
- Sanitary Drainage (slab on ground) applications are to be installed with DN100 x DN100 Traps as best practice, and,
- Sanitary Plumbing (stackwork) applications are to be installed with the relevant Sanitary Plumbing System sizing methods and by calculating the sum of the fixture unit ratings of the fixtures connecte
Bath requirements
AS/NZS 3500.2:2021 – Sanitary Plumbing and Drainage
Clauses 13.9 Baths
Baths shall be connected by –
(a) an untrapped waste pipe not smaller than DN 40 to a floor waste gully in accordance with Table 4.6.7.2;
(b) a trap and waste pipe not smaller than DN 40
Where a bath trap is not accessible, the bath shall discharge untrapped to a floor waste gully (FWG) in accordance with Table 4.6.7.2 and Appendix B.
Compliant Deemed-to-Satisfy installation of a bath where a trap cannot be installed due to not being accessible (ie slab on ground type construction).
The following is not considered to comply with the AS/NZS 3500.2:2021 requirements:
- Bath to discharge through a disconnector gully with sealed lid internal or external of building
- Non-accessible trap installed beneath bath
AS/NZS 3500 Part 0 Glossary of Terms provides a definition of Accessible.
Accessible:
Capable of being reached for the purpose of inspection, maintenance, repair, or replacement, but may first require removal of an access panel, cover, door or similar obstruction.
Shower requirements
AS/NZS 3500.2:2021 – Sanitary Plumbing and Drainage
Clauses 13.17.1 Individual showers
An individual shower shall be fitted with a minimum DN80 grate or channel grate, and shall be connected by –
(a) an untrapped waste pipe not smaller than DN 40 to a floor waste gully; or
(b) a trap and waste pipe not smaller than DN 40
Prefabricated shower bases will need to be supported in accordance with the manufacturer’s instructions.
Consideration needs to made when selecting products, as not all Watermark approved products are fit for purpose to comply with the above clause.
Note:
Information contained within this document is current as of June 2023 and refers to codes and standards current at the time of writing.
NSW Fair Trading disclaims any liability (including for negligence) to any person in respect of anything done, or not done, by that person in whole or partial reliance on any of the information in this advisory note.