The National Construction Code (NCC) outlines vital information for building owners and developers to adhere to within Australia. The code contains everything from energy efficiency to waterproofing, including floor waste requirements that need to be adhered to. Failing to meet these requirements could end in fines and prosecution, and even demolition if the concern is high enough.
While the standards can be frustrating for developers, the NCC is in place to benefit homeowners from safer, healthier living conditions. Explore everything you need to know about the NCC’s floor waste requirements for Class 1 buildings below.
Table of Contents
What is a class 1 building?
A Class 1 building is either a domestic or residential building, whether that be a single, standalone single, townhouse, row house, or horizontally attached house. There are two sub-categories of Class 1 buildings:
- Class 1a: A single dwelling or one of a group of attached dwellings, such as a terraced house
- Class 1b: A boarding house, guest house, or hostel with a floor area of less than 300 square metres
An overview of NCC floor waste requirements
Here’s an overview of the specific floor waste requirements outlined in various sections of the NCC:
Floor waste gully requirements
NCC 2022 Vol 1 and 2 – Building Codes of Australia 2022
Floor wastes are needed in certain wet areas. Specific requirements can be found in:
- Part F2 – Wet Areas and overflow protection(for Class 2 to 9 buildings)
- Part H4 – Health and Amenity (for class 1 and 10 buildings)
NCC Vol 3 – Plumbing Code of Australia 2022
Part C1 Sanitary plumbing systems(C1D2 Invert levels)
The trap or gully weir’s invert level must be a minimum of 10 mm higher than the soffit of the pipe to which it connects.
Part C2 Sanitary drainage systems(Clause C2D2 Invert levels)
The trap or gully weir’s invert level must be a minimum of 10 mm higher than the soffit of the pipe to which it connects.
AS/NZS 3500.2:2021 – Sanitary Plumbing and Drainage
4.6.7.6 (Removable grate)
Floor waste gullies need to be installed with a grate that’s both accessible and removable, as well as have a riser of not less than DN 80 to the finished floor level. When the sole function of the floor waste gully is to dispose of water, a minimum DN 50 riser can be used.
4.6.7.7 (Height of gully riser)
The height of your gully riser must be measured from the top of the water seal to the floor surface level, adhering to the following:
- For floor waste gullies with connections to a gully riser, the maximum height should be 600 mm
- For floor waste gullies with submerged inlets, the minimum height should be 100 mm
Bath requirements
AS/NZS 3500.2:2021 – Sanitary Plumbing and Drainage
13.9 (Baths)
Baths must be connected by:
- An untapped waste pipe not smaller than DN 40 to a floor waste gully
- A trap and waste pipe not smaller than DN 40
If the bath trap isn’t accessible, the bath needs to discharge untapped to a floor waste gully. This is considered a Deemed-to-Satisfy compliant pathway.
Shower requirements
AS/NZS 3500.2:2021 – Sanitary Plumbing and Drainage
13.17.1 (Individual showers)
An individual shower must be fitted with a minimum DN 80 grate or channel grate, and connected by:
- An untapped waste pipe not smaller than DN 40 to a floor waste gully, or
- A trap and waste pipe not smaller than DN 40
Specific NCC requirements for floor waste in class 1 buildings
Whether a Class 1 building needs a floor waste system or not is all dependent on whether the shower area, which the BCA defines as the ‘area affected by water from a shower, including a shower over the bath’, is enclosed or not.
- Enclosed showers are designed to control the spread of water within the shower by a screen door. Enclosed showers should not leak from the shower area and therefore don’t need a floor waste.
- Unenclosed showers are where the shower is open on one or more sides and can include frameless shower screens. This area is defined by an arc that extends 1500 mm from the shower connection at the wall. A floor waste will most likely be needed here as the bathroom floor would need to be drained to remove excess water.
It’s important to remember that in Class 1 buildings, floor waste systems aren’t always required. If one is provided or needed, the bathroom floor must be graded to that floor waste and other compliance requirements need to be met when it’s installed.
Read more about floor waste requirements, and when they’re not needed for Class 1 buildings, here.
How do these requirements impact building costs?
Depending on the type of floor waste system you’re installing, the price can vary from $100 to $1000 and over – which is why it’s so important to know whether you need a floor waste system in your new build. Most Class 1 buildings won’t need one unless you’re building with extenuating circumstances, for example, an unenclosed shower to accommodate people who would benefit from a wet room.
Our advice is to talk with your building certifier to get a clear decision on whether you need a floor waste system or not. If these requirements don’t apply to you, you can save yourself some money and put your budget to better use.
Deemed-to-Satisfy (DtS) provisions
Deemed-to-Satisfy (DtS) provisions are put in place when you cannot meet the requirements set out in the NCC. For example, if your bath trap isn’t accessible when installing it, there are accepted DtS provisions you can use to prove your compliance.
Taking this example, the compliant DtS installation would be as shown below.
This installation is considered compliant with the NCC requirements and therefore should be accepted.
However, here are some examples of alternative solutions that don’t comply with the NCC requirements and therefore cannot be used:
- Having the bath discharge through a disconnector gully with a sealed lid, whether that’s internal or external
- Installing a non-accessible trap beneath the bath
Performance solutions
Performance solutions tend to be a little more relaxed than DtS solutions, offering you another method or material to use should you not be able to meet the floor waste requirements set out by the NCC. The performance solution you’ll use will depend on the problem you’re facing, and it will be assessed by one or more of the following:
- Evidence of suitability
- Expert judgement
- Verification methods
- Comparison with Deemed-to-Satisfy provisions
As long as the end result meets or exceeds the performance requirement set by the NCC, it should get accepted as you’ve shown your willingness to comply with the requirements.
Exceptions and variations to the floor waste requirements
For Class 1 buildings, you don’t always need a floor waste system. The only reason you’d need one is if you were creating a wet room rather than a bathroom with an enclosed shower or a shower over a bath.
However, floor wastes are often installed voluntarily in wet areas that don’t actually need them (such as Class 1 buildings), even though the NCC states that this isn’t a requirement.
This is because most homeowners would expect to see floor waste installed in a wet area, so it can be a cause for concern if your building doesn’t feature one. Builders and plumbers can discuss the requirements for the NCC with the owner to make sure they understand when it’s needed.
Common issues with floor waste requirements and how to avoid them
When installing floor wastes, there are a few issues you can run into which can lead to delays and extra purchases needing to be made. Here are some common issues and how we recommend avoiding them:
- Using a floor waste when you don’t need to, or vice versa: If you’re not 100% sure whether you need a floor waste system installed or not, you might end up making the wrong decision. We highly recommend you talk to your plumber or building certifier to make sure you know whether you need floor waste or not so you can make an informed decision.
- Confusing your shower type: Unenclosed showers need floor waste systems, but these can still have partial or frameless shower screens attached which might make you think they’re deemed enclosed. Unenclosed showers are defined by an arc that extends 1500 mm from the shower connection at the wall where water extends into the rest of the wet room. To avoid this, we recommend talking to your plumber or supplier to make sure you know which type of shower you’re using.
- Choosing the wrong contractor: It happens to the best of us, but some contractors are more skilled in certain areas than others. When it comes to floor waste, when there’s so much that could go wrong in terms of damp and mould, it’s essential that you choose the best contractor for the job. Check customer testimonials, previous reviews, and qualifications to make sure you’re making a sound choice.
Key inspection and compliance tips
Here’s some of our favourite tips and tricks to make sure your floor waste system passes its inspection and complies with the NCC’s requirements:
- Consult multiple plumbers and building certifiers to get the best advice on whether you actually need a floor waste system or not
- Installing floor wastes when you don’t need one can make you liable for neglecting NCC requirements, even though it wasn’t necessary in the first place
- Locate the floor waste system correctly and enlist the help of a trusted plumber who knows the guidelines on how to do this
- Brush up on your NCC knowledge and make sure you’re aware of the requirements around floor waste for Class 1 buildings yourself to make sure you’re not blindly trusting another professional’s advice
- If you already have a homeowner lined up, consult them and make sure they’re happy with your decision to add or skip the floor waste system and explain whether they need it or not
Explore other NCC requirements and regulations
- NCC changes 2024
- NCC energy efficiency requirements
- NCC waterproofing requirements
- NCC handrail requirements
- NCC disability access requirements
Get free advice from an experienced building broker on your new build
While the idea of floor waste system regulations for Class 1 buildings seems pretty straightforward, there’s still a lot of information to get through when looking into it yourself. Buildi prides itself on its team of experts on hand to give you free advice whenever you need it, so why not get in touch with us today at 1300 947 132 or through our Contact Form and let us help?
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