What Building Class Is My Project?
A plain-language guide to the NCC building classification system, what each class covers, and why your building class matters for certification.
Last reviewed: 2026-03-19
Why building class matters
The National Construction Code (NCC) classifies buildings from Class 1 through Class 10 based on their intended use. The building class determines which NCC requirements apply to your project -- including structural standards, fire safety, accessibility, energy efficiency, and weatherproofing.
It also determines what level of certifier accreditation you need. Some certifiers are only accredited for residential (Class 1 and 10), while others hold unlimited accreditation for all building classes. Getting the class right at the start avoids wasted time and fees.
Residential: Class 1
Class 1a is a standalone single dwelling (house, townhouse, or terrace where each dwelling is on its own allotment). This is the most common building class and includes granny flats (secondary dwellings).
Class 1b is a small boarding house, guest house, or hostel with a floor area not exceeding 300 square metres and accommodating no more than 12 people. Most residential certifiers (residential accreditation level) can certify Class 1 buildings.
Multi-residential and commercial: Classes 2-9
Class 2 covers apartment buildings (each dwelling is a separate unit within a larger building). Class 3 covers hotels, motels, backpackers, and similar accommodation. Class 4 is a dwelling attached to a non-residential building (e.g., a caretaker's flat above a shop).
Classes 5 through 8 cover commercial and industrial buildings: offices (5), shops and restaurants (6), car parks and warehouses (7a and 7b), and factories (8). Class 9 covers public buildings: hospitals (9a), schools and churches (9b), and aged care facilities (9c).
All Class 2-9 buildings require a certifier with unrestricted or unlimited accreditation. The NCC requirements for these classes are significantly more complex than for residential buildings, particularly for fire safety and accessibility.
Non-habitable structures: Class 10
Class 10a covers non-habitable buildings such as sheds, carports, and garages. Class 10b covers non-habitable structures such as fences, retaining walls, and antenna masts. Class 10c covers swimming pools and spas.
Class 10 structures have simpler NCC requirements than habitable buildings but still require certification in most cases. Small structures below a certain size (which varies by state) may qualify as exempt development requiring no approval at all.
Mixed-use and multiple classifications
A building can have multiple classifications. A shop with an apartment above is both Class 6 and Class 2. A house with an attached garage contains Class 1a and Class 10a elements. Your certifier determines the classification for each part of the building.
Where multiple classes apply, the highest-class requirements generally govern the common elements (structure, fire separation). Your certifier works through the classification and applicable requirements during the plan assessment stage.
Official Sources
Verify the information in this guide against these official government resources.
- Australian Building Codes Board
The body responsible for the NCC, which defines building classifications.
- Building Class Finder Tool
Use our interactive tool to identify the likely building class for your project.