Mezzanine Fire Safety Requirements: How the NCC Treats Mezzanines

If you want to understand mezzanine fire safety requirements, start with one idea: the National Construction Code (NCC) does not treat every mezzanine the same. Size, use and the room around it decide whether your mezzanine is a minor internal platform or a feature that changes how the whole building is assessed for fire.

This guide is a national overview. It explains the storey rule that catches many owners out, why it exists, and what to raise with your certifier or building surveyor.

What the NCC is, and who applies it

The NCC is the national technical code for building work in Australia, and the person who assesses your design against it is a building certifier or building surveyor. They will confirm what the NCC requires for your specific building.

That is why general articles, including this one, can only get you so far. The class of building, the layout and the use of the mezzanine all feed into the answer.

NCC mezzanine fire requirements: when does a mezzanine count as a storey?

The most useful single rule for owners is in NCC 2022 Volume One, clause C2D3(4). For calculating rise in storeys, a mezzanine is regarded as a storey if its floor area is:

• more than 200 m², or
• more than one-third of the floor area of the room,

whichever is the lesser.

Two or more mezzanines at or near the same level are aggregated for this test. The clause sits in Part C2, Fire resistance and stability: https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-one/c-fire-resistance/part-c2-fire-resistance-and-stability

A worked example of the thresholds

Say a factory room has a floor area of 450 m². One-third of that is 150 m². The lesser of 200 m² and 150 m² is 150 m², so a mezzanine over 150 m² would be regarded as a storey for the rise-in-storeys calculation.

In a much larger room, say 1,500 m², one-third is 500 m². The lesser of 200 m² and 500 m² is 200 m², so the 200 m² figure governs.

These figures are illustrations of how the test works, not advice on your building. Your certifier will run the numbers using your actual room area and layout.

Why the rule exists

ABCB guidance on the same page explains the reasoning. Larger mezzanines are included in rise in storeys because of their potential fire load. And rise in storeys feeds into fire-resisting construction requirements.

In plain terms, a bigger mezzanine can mean the building is treated as having more storeys, and that can change what fire-resisting construction is expected. That is a design and cost issue, and it is far better to know before you finalise the layout.

Aggregation: why two small mezzanines can add up

Owners sometimes plan two or three smaller platforms to stay under a threshold. The aggregation rule is why that does not automatically work. Mezzanines at or near the same level are added together for the test.

If you are considering a staged expansion, tell your certifier about the whole plan. Label Power's staged approach is a good example of how mezzanines can grow over time: https://factorymezzaninefloors.com.au/projects/label-power

When you are planning to build in stages, raise this early with your designer and certifier so the total area is assessed properly.

Egress and existing fire systems

The storey rule is one part of the picture. The way people reach an exit and the way a new level interacts with the building's existing fire protection are also worth raising with your certifier early. Which provisions apply depends on your building class and design, and your certifier or building surveyor will confirm them.

Egress is a design decision, not a finishing touch

Stairs take up floor area on both levels, and they affect how you use the space. Moving them late in a project is expensive. Settle the exit strategy at the layout stage and ask your certifier what they need to see.

You can read more about stair options on our stairs page: https://factorymezzaninefloors.com.au/mezzanines/mezzanine-stairs

Fire systems in the existing building

If your building already has sprinklers, detection or alarms, the new level may affect them. Tell your certifier what is installed today so they can advise whether anything needs to change.

Approvals depend on your site

The approval process you follow depends on where your site is, and your certifier or building surveyor will confirm it.

A practical checklist for owners

Before you brief a designer, gather this information.

1. The floor area of the room the mezzanine will sit in.
2. The proposed mezzanine area, and any other mezzanines at or near the same level.
3. What the mezzanine will be used for and by how many people.
4. What fire systems the building already has.
5. Where exits are today, and where the stairs could go.
6. Your growth plans, so the design can allow for them.

With that in hand, your certifier can give a much clearer view of how the NCC applies.

How FMF helps

At FMF, our team designs, engineers and installs mezzanines, and manages council approval as part of the job. If you want an early view of how size and layout affect your project, our consulting service is the place to start: https://factorymezzaninefloors.com.au/mezzanines/consulting

Get a clear answer for your building

If you are planning a mezzanine and want to know how the NCC will treat it, call 1300 998 883 or request a free quote. We can also arrange an obligation-free site consult to review your room size, layout and the questions to take to your certifier.

FAQs

Does the NCC give the same answer for every mezzanine?

No. The result depends on your room size, layout, building class and use. Your certifier or building surveyor will confirm how the NCC applies to your project.

Why does the NCC care about mezzanine size?

ABCB guidance says larger mezzanines are included in rise in storeys because of their potential fire load, and rise in storeys feeds into fire-resisting construction requirements.

When does a mezzanine count as a storey under the NCC?

Under NCC 2022 Volume One, clause C2D3(4), a mezzanine is regarded as a storey for calculating rise in storeys if its floor area is more than 200 m² or more than one-third of the floor area of the room, whichever is the lesser. Two or more mezzanines at or near the same level are aggregated.