All you need to know about NCC building classes
If you are constructing a building or trying to comply with NCC, you will come upon provisions that apply to some specific building class numbers. But what are these building classifications and what exact type and use of buildings they apply to? In this article, we cover all you need to know about NCC building classes.
Why are buildings classified?
Buildings differ from one another in the activity of occupants and energy use. The primary reason for the classification of buildings is to address different provisions and laws to buildings regarding their specific aspects and conditions. To simplify referencing to specific building types, NCC classifies buildings into ten categories.
NCC building classification
According to NCC Vol 1.0 Part A6, there are 10 building classifications:
- NCC Volume one covers building classes 2 to 9.
- NCC Volume two covers building classes 1 and 10.
- NCC Volume three covers all building classes.
Below, we summarise all building classes with typical space use:
Dwelling in a commercial building
There are also sub-classifications for several building classes. NCC refers these sub-classifications to different building classes using a letter after the class number (e.g. class 1a or 9b).
In the following, we describe all building types in full details:
What is NCC Class 1 building?
Class 1 building is a standalone single dwelling, typical houses where a single-family lives in. Standalone attached houses in a single story are still classified as Class (not vertically, i.e. apartments).
Class 1a building – a detached house or one of a group of two or more attached houses in class 1a buildings we expect an owner/tenant/lessee with a permanent occupation of the building.
Class 1b building
- One or more buildings that together form a boarding house, guest house, hostel or the like with two conditions:
- The building should not accommodate over 12 people; and
- The building should not have more than 300m2 floor area of all floors
- Four or more single dwellings in one allotment that are used for a short period.
In class 1b buildings we expect an owner/tenant/lessee with a temporary occupation of the building.
Examples of NCC class 1 building:
- Class 1a building: single-family dwelling, row house, terrace house, villa house, townhouses, duplexes or the like.
- Class 1b building: board house, guest house, a hostel or the like.
- We refer the wall separating Class 1 building from another class 1 buildings to as a “separating wall” in NCC. The wall separating class 1 from any other building class is referred to as “common wall” in NCC. For all other building classes, we refer both above walls as “common walls” in NCC.
- NCC energy efficiency requirements for class 1 is more demanding. For instance, there are some cases that the Building fabric and glazing thermal performance requirements for a class 1 building demand almost twice the insulation than any other building classes.
- Class 1a building can benefit from performance solutions like VURB or NatHERS Energy Rating, however, class 1b can only benefit from VURB and not the Energy Rating. [Reference]
What is NCC Class 2 building?
Class 2 building are apartments, where 2 or more “sole-occupancy unit” Sole occupancy unit is a building where independent owners/lessees/tenants live in. NCC defines class 2 as a building that contains two or more sole- occupancy units.
Example of NCC class 2 building:
- Apartments, separate dwellings above a common space.
- Although we expect that sole-occupancy unit in a class 2 buildings to be vertically aligned, this is not always the case. We can have multiple separate dwellings beside each other on the same level above a common space (e.g. basement or carpark) to form a class 2 building.
- Unlike class 1 buildings, there are no elemental provisions (i.e. Deemed to Satisfy – DtS provisions) for class 2 buildings (except for class 2 common areas). Therefore, regarding class 2 sole-occupancy units, performance solution must be applied to meet NCC performance requirements using NatHERS approved tools. [reference]
What is NCC Class 3 building?
Class 3 building is a commonplace providing long-term or short-term accommodation for several unrelated people. Whenever a building that accommodates people is not a class 1a, 1b, 2 or class 4, then it is a class 3 building.
Examples of NCC class 3 building:
- Board house, guest house or hostel built for the accommodation of over 12 people or with floor area more than 300m2 (larger than the limits of class 1b)
- Backpackers accommodation, dormitory-style accommodation
- The residential part of hotels, motels, schools, health care buildings or detention centres that can’t be specified as a class 4 building.
- A care-type facility such as accommodation building for children, elderly or people with disabilities that can’t be specified as a class 9 building.
- Class 3 building can be easily mistaken from a class 1b, 2, 4 or 9c building. So it may be a more straightforward way to pin-point on definitions of these classes instead of class 3 buildings.
- Unlike class 2 sole-occupancy units and class 4 part of a building, there are elemental provisions (i.e. DtS provisions) for class 3 buildings inside NCC Vol 1.0. [NCC 2019 Vol 1.0, Section J, Part J1, J1.1]
- Considering wall-glazing construction, NCC is more demanding from class 3 compared to class 5 to 9 buildings (except 9a and 9c ward) and less demanding compared to class 1a or 1b buildings. This also applies to roof and roof lights for class 1a or 1b buildings.
- Section J verification method JV3 can be applied to class 3 building as a performance solution. [NCC 2019 Vol 1.0 Section J, JV3 (a)]
What is NCC Class 4 building?
Class 4 is a sole dwelling in class 5 to 9 building (i.e. in a non-residential building). This only applies if it is the only dwelling in the building, so NCC suggests the definition of “class 4 part of a building”.
Example of NCC class 4 building:
- Caretaker’s residence in a commercial building like a factory, school or storage facility.
- There can only be one class 4 in a building with a non-residential nature.
- Similar to class 2 sole-occupancy units, there are no elemental provisions (i.e. DtS provisions) for class 4 part of a building. Therefore, performance solution must be applied to meet NCC performance requirements using NatHERS approved tools. [NCC 2019 Vol 1.0, Section J, Part J1, J1.1]
What is NCC Class 5 building?
Class 5 building is an office building, used for commercial or professional purposes. By an exclusive term, class 5 building is a building that can’t be classified as a class 6,7,8 or 9 building.
Examples of NCC class 5 building:
- Office buildings for lawyers, architects, government agencies, etc.
- A building used for physiotherapy.
- Medical practitioner’s offices are classified as class 5 and not class 9, as long as medical treatments don’t leave patients in a state of non-ambulatory or unconsciousness.
- Besides Section J verification method JV3 and Green Star, NABERS verification method can also be used for offices. [NCC 2019 Vol 1.0 Section J, JV1 (a)]
What is NCC Class 6 building?
Class 6 building is a commercial building to sell goods by retail or to provide services directly to the public. The word “direct” is of importance here since wholesale warehouses or food production facilities that are not directly selling to the public are not included in the definition of class 6 buildings.
Examples of NCC class 6 building:
- Shop, mall, mart, retails, kiosk, showrooms.
- Restaurant, café, bar, dining room.
- Hairdresser or barbershop, funeral parlour, service station, public laundry.
- Service stations exclude places where solely alterations happen; For example carwashes, panel beating, auto electrical, tyre replacement or the like. We classify these buildings as class 8 buildings.
- There are some changes to the definition of a class 6 building in NSW and SA states. [NCC 2019 Vol 1.0, Section A, Part A6, A6.5]
What is NCC Class 7 building?
Class 7 building is a storage-type building. This includes storage of cars or goods.
Class 7a building – Carparks.
Class 7b building – Warehouse or a storage facility that is used for storage, production or display of goods for sale by wholesale (not directly to the public)
Examples of NCC class 7 building:
- Class 7a: Carparks
- Class 7b: Large storage sheds, warehouses, animal shelters
- We may not consider class 7 buildings as part of the building envelope and hence, provisions of energy efficiency may not be inclusive of these buildings. This applies where class 7 parts of a building are unconditioned (not occupied for business by people) and form a common wall with the rest of the building or below the rest of the building.
- A carpark may be classified as 7a, 8 or 10a depending on the building size, purpose or occupancy. [reference]
What is NCC Class 8 building?
Class 8 building is a process-type building. A factory or laboratory is the most common way to describe class 8 buildings. Class 8 ultimately is a place for production, alteration, assembly, repair, finishing, cleaning or packing of goods to sale, trade or gain.
Examples of NCC class 8 building:
- Factory, mechanic’s workshop, abattoir (or any other food processing facility), grow room
- Laboratories must never be classified as another class (where its area is less than 10% of the total area in a story). This is due to the high fire-hazard conditions in a laboratory, with an exception of laboratories that are part of a health-care building, where it must be classified as class 9a or part of a school where it must be classified as class 9b.
- Farm buildings may be of class 7, 8 or 10a. This depends on the building’s size, purpose, operations and the extent to which people are employed in the building. This decision is made by appropriate authorities in different states and territories.
- There are specific Deemed to Satisfy (DtS) provisions for farm building in NCC 2019 Vol 1.0 Part H3.
- A workshop in a school is classified as class 9b. [NCC 2019 Vol 1.0, Section A, Part A6, A6.9 (2)]
What is NCC Class 9 building?
Class 9 building has a purpose to serve the public with services that regard spiritual affairs, well-being, information or rather any other purpose for social gatherings.
Class 9a building – these building are hospitals or clinics or, as NCC prefers, health-care buildings. They are buildings in which occupants or patients are undergoing medical treatment and may need physical assistance to evacuate in the case of an emergency. This includes practitioner’s offices that their treatments of patients may result in them being unconscious.
Class 9b building – these buildings are assembly buildings in which people gather for political, social, theatrical, religious or other civil purposes.
Class 9c building – these buildings are residential care buildings where at least 10% of people who reside there need physical assistance in conducting their daily activities.
Examples of NCC class 9 building:
- Class 9a: hospitals, ward areas, clinics, day surgery, the health-care building used as a residential care building, nursing homes.
- Class 9b: cinemas, theatres, conference facilities, churches, schools, universities, museums, gyms, night clubs, public transport facilities, child-care centres.
- Class 9c: aged care buildings, residential care buildings.
- Considering wall-glazing construction, NCC is less demanding from class 9b compared to class 9a (ward area) or 9c buildings.
- A care building could be a class 3, 9a or 9c. This depends on the variation and the degree of care these buildings present. As an example, if there’s a variation in care the elders’ demand, most likely the building has to be classified as class 9c. However, if the occupants need the same degree of care and the level of care is high, then it has to be classified as class 9a. [NCC 2019 Vol 1.0 Part A6, Explanatory information, Page 38]
What is NCC Class 10 building?
The main characteristic of a class 10 building is that it is either a non-habitable building or simply a structure like an antenna where the definition of a building is not applied to it.
Class 10a building – is a non-habitable building that is not built for safety reasons.
Class 10b building – is a structure in an allotment where the building is located in.
Class 10c building – is a private bushfire shelter that is not attached to class 1 building.
Examples of NCC class 10 building:
- Class 10a: private garage, carport, shed.
- Class 10b: fence, mast, antenna, retaining or free-standing wall, swimming pool associated with class 1 building
- Class 10c: private bushfire shelter.
- A private garage is associated with a class 1 building. Garages that are associated with other types of buildings are private garage (class 10a) where the building is a single-story building with a garage containing not more than 3 vehicle spaces (also true for multiple story buildings with a garage as one story not containing more than 3 vehicle spaces).
- A private small farm shed with no commercial purposes is considered as class 10a.
- To decrease glazing cost for class 1 buildings, attached garages may be included to have the same thermal performance as class 1 building. This is certainly the case where the garage floor area is great with comparison to the rest of the building and has minimum or no glazing.[NCC 2019 Vol 2.0, Part 220.127.116.11, Explanatory information, Page 387]
Can I combine two or multiple buildings classes into one to simplify energy compliance?
The answer is yes. If parts of your building meet the following criteria, you might classify these parts of your building in the same building classification as the major part of your building [NCC 2019 Vol 1.0 Part A6.0 (2)]:
- Both building classes have to be inside the same story; and
- The minor use must not be class 2,3,4 or class 8 (laboratory); and
- The minor use floor area must be less than 10% of the floor area of that story.
Also, rooms with general use like WC and rooms that contain mechanical, electrical or thermal facilities like plant rooms are all classified as the major use of building. This also includes occupiable outdoor areas (unless another building classification is more suited for it). [NCC 2019 Vol 1.0 Part A6.0 (4)]
Note that NCC expects you to classify each part of building according to its specific use and purpose, and each classification must comply with its requirements and conditions.