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Wet Area Floor Wastes in Queensland (QDC MP 4.5)

Queensland does not make you put a floor waste in a bathroom or laundry. Only the shower needs one. Fit one anyway and the QDC sets the fall at 1:100 to 1:80.

NCC 2022 Clause QLD QDC MP 4.5 Clause HP 10.2

The requirement

Queensland does not make you put a floor waste in a house bathroom or laundry. The one place you must have one is the shower (NCC 2022, clause 10.2.14). Fit one anywhere else and the floor must fall to it at 1:100 to 1:80 (QDC MP 4.5).

Queensland houses, sheds and decks are still built to NCC 2022. The state has put NCC 2025 back to 1 May 2027. So NCC 2022 sits behind every wet area job you price today.

A floor waste is the drain in the floor of a wet room. Some people think the code makes you fit one in every bathroom. It does not. The Queensland Government itself calls them non-mandatory. South Australia is the only state that forces one into a wet area floor.

The shower is the exception. Every shower area needs a floor waste, walled in or open. That is clause 10.2.14 of the building code, and it applies in Queensland.

Fit a waste, and the fall rule kicks in. The rule comes from the Queensland Development Code, Mandatory Part 4.5. The floor plane must fall to the waste at no less than 1:100 and no more than 1:80. That is flatter than the national range of 1:80 to 1:50 in clause 10.2.12. In Queensland the QDC wins.

So the state rule is a break, not extra work. It lets you lay a flatter floor. It does not tell you to put a waste in.

Shower floors sit outside this. Grade the part of the floor that drains the shower to the national fall of 1:80 to 1:50. Rooms with a urinal are left out of the QDC rule too.

The fall rule covers houses and small guest houses (Class 1a and 1b). It also covers ground floor or entry level units in a Class 2 block.

You can skip the fall. QDC MP 4.5 gives you four other ways. Take any one of them and the floor does not have to be graded at all.

  • Run a linear drain right across each way into the wet room. Hook it up to the plumbing.
  • Set a weir across the full width of each way in. Keep it at least 10 mm above the top of the floor waste, and no steeper than 1:8. It has to sit in the door jamb, or within 100 mm of it. That is A5(2)(c).
  • Or set a weir at least 10 mm above the top of the floor waste with no 1:8 limit. The floor fall from the way in must then be no steeper than 1:80. That is A5(2)(d).
  • Fit full overflow cover, as set out below.

That last one has three parts. Every basin, bath and tub needs a built-in overflow. Every toilet cistern needs an overflow that runs back into the pan. Every flexible hose needs a flood stop valve to WMTS-479. Do all three and the floor can stay flat.

There is one more let-off. Say a floor area is cut off from the way in by a graded area that is served by a floor waste. That far area does not have to be graded. Every fixture has to sit on the graded area, or behind it.

The QDC beats the code here. MP 4.5 says so in its own words. It overrides the building code where the two do not agree. That line comes from the Guide in MP 4.5. Section 14 of the Building Act 1975 then sets out how you comply with a QDC criterion.

Check the version before you lean on it. We checked MP 4.5 Version 1.2. It came out on 24 January 2025 and started on 10 March 2025. Version 1.3 came out as a pending part on 3 August 2026, and it sits on the QDC register. It does not change the grading rules. P5 and A5 read word for word the same. That covers the 1:100 to 1:80 fall and the linear drain, weir and overflow ways out. It adds new criteria P6 to P8. It also runs the affected-lot livable housing let-off out to 30 September 2029. Its start date is still blank. So Version 1.2 is the one in force.

Sources

  • Queensland Development Code, Mandatory Part 4.5 “Livable dwellings and grading to floor wastes”, Version 1.2 (published 24 January 2025, commenced 10 March 2025) — Chapter 2.2 performance requirement P5 and acceptable solution A5. A5(2)(a) sets the 1:100 minimum and 1:80 maximum fall where a floor waste is installed, noted as varied to align with AS 3740:2021. A5(2)(b) to A5(2)(e) with A5(3)–A5(4) give four alternatives that remove the grading requirement — a full-width linear drain; a weir across the full extent of the entrance, at least 10 mm above the waste, max 1:8 gradient, located within (or within 100 mm of) the door jamb (A5(2)(c)); a weir at least 10 mm above the waste where the fall of the floor plane from the entrance does not exceed 1:80 (A5(2)(d)); and full overflow protection (A5(2)(e)). A5(5)–A5(7) further exempt any floor area separated from the entrance by a complying graded area served by a floor waste, provided all fixtures sit on or behind that graded area. Clause 4 Table 1 sets the Class 1a, 1b and ground/entry-level Class 2 scope; clause 11 excludes rooms containing a urinal and the part of a floor draining a shower area. The Guide and clause 5 state that the QDC part overrides the BCA where inconsistent, with compliance under section 14 of the Building Act 1975 (Qld). Find the current listed version on the official QDC register at business.qld.gov.au, which links the MP 4.5 PDF.
  • NCC 2022, ABCB Housing Provisions Standard, Part 10.2 “Wet area waterproofing” — clause 10.2.12 sets the national wet area floor falls (1:80 minimum, 1:50 maximum) where a floor waste is installed; clause 10.2.14 requires a floor waste in every shower area, enclosed or unenclosed. Part 10.2 carries no Queensland variation (the Queensland schedule varies termite management only). South Australia’s clause 10.2.33 is the sole state provision requiring wet area floors to be graded to a floor waste. ncc.abcb.gov.au
  • NCC 2025 Volume Two, Queensland Introduction (ABCB state adoption schedule) — Queensland remains on NCC 2022, and all NCC 2022 provisions stay in force there until 30 April 2027. NCC 2025 does not take legal effect in Queensland until 1 May 2027. ncc.abcb.gov.au
  • Queensland Department of Housing, Modern Homes transitional arrangements — describes the QDC provisions as applying to “non-mandatory floor wastes”, confirming that floor wastes in Class 1 bathrooms and laundries are not required in Queensland. housing.qld.gov.au
  • QDC MP 4.5 Version 1.3 (pending) — published 3 August 2026 and listed under “Pending mandatory parts” on the QDC register. Chapter 2.2 P5/A5 is unchanged from Version 1.2 (1:100 minimum, 1:80 maximum, same A5(2)(b)–(e) alternatives). It adds performance criteria P6–P8 and extends the affected-lot livable housing exemption to 30 September 2029. The commencement date is not yet stated in the published document (“Commenced on insert date”), and Table 1 shows “XXX” for both publication and commencement date, so Version 1.2 remains in force. pending publication version PDF

State variations

These states apply requirements that differ from the national provisions for this rule.

  • Queensland Announced HP 10.2

    Current code: NCC 2022

    Queensland does not require a floor waste in a Class 1 bathroom or laundry — only in shower areas (10.2.14). Where one is installed, QDC MP 4.5 relaxes the fall to 1:100–1:80 (national range is 1:80–1:50), and allows a linear drain, a 10 mm weir or full overflow protection instead of grading the floor at all.

    Queensland building codes → Official source → Verified 2026-08-06

Related building rules

Content adapted from the National Construction Code 2022, provided by the Australian Building Codes Board under the CC BY 4.0 licence.

Frequently asked questions

Do you need a floor waste in a bathroom in Queensland?
Not in a house. Queensland has no rule that makes you put a floor waste in a bathroom floor. The one place you must have one is the shower area, walled in or open. That comes from the building code, clause 10.2.14. Outside the shower, a floor waste is your choice.
Does a laundry need a floor waste in QLD?
No. Neither the building code nor any Queensland rule makes you put a floor waste in a house laundry. The state calls them non-mandatory. If you do fit one, the floor around it has to fall to it, unless you use one of the other ways out in QDC MP 4.5.
What fall does a floor waste need in Queensland?
The floor must fall to the waste at no less than 1:100 and no more than 1:80. That is QDC MP 4.5. It is flatter than the national range of 1:80 to 1:50. Shower floors are the odd one out and keep the national fall.
Can a Queensland bathroom floor be laid flat with no fall?
Yes, in some cases. QDC MP 4.5 gives you four ways out. Run a linear drain across each way in. Or set a weir across each way in. Or set a weir with the floor fall held to 1:80. Or fit full overflow cover to every vessel, cistern and hose.
Which NCC edition applies in Queensland right now?
Houses and sheds in Queensland are still built to NCC 2022. The state has put NCC 2025 back to 1 May 2027. So NCC 2022 is the edition behind the wet area rules on your job today.