All you need to know about NCC building classes
If you are constructing a building, assessing for its energy efficiency requirements, you will have to use NCC and in it, you sure will come upon provisions that are applied to some specific building class numbers. But what are these numbers 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 are different to one another in their degree of activity, energy use, fire-sensitivity and such. The main reason for classification of buildings is to address different provisions and laws to buildings with regard to their specific aspects and conditions. In order to simplify the references to specific buildings, NCC classifies buildings into ten categories of reference. The users of NCC must be aware of different building classifications and their differences. Although there may be some state or territory variation to the NCC, national perspective of the building classification is described within it.
NCC building classification
According to NCC Vol 1.0 Part A6, there are 10 building classifications:
- NCC Volume one covers mostly building classes 2 to 9.
- NCC Volume two covers mostly building classes 1 and 10.
- NCC Volume three covers all building classes.
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).
Each part of building must be classified according to its specific use and purpose and each classification must comply with its own appropriate requirements and conditions. You may have part of the building with minor use to be classified as the part with major use (with greater area) but there are some conditions to it:
- Both building classes have to be inside one 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).
Providing above basic information, the ten building classes are described as below:
Class 1 building are standalone single dwelling, typical houses where a single family lives in. Class 1 buildings may be attached to one another horizontally and stay class 1 (not vertically, i.e. apartments).
Class 1a building – May be 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 board house, guest house, hostel or the like with two conditions:
– not to accommodate more than 12 people; and
– not to have more than 300m2 floor area of all floors
- Four or more single dwellings in one allotment that are used for a short period of time (like holidays).
In class 1b buildings we expect an owner/tenant/lessee with a temporary occupation of the 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, hostel or the like.
- Class 1 building is separated from another class 1 buildings with a “separating wall”, and from a different class building with a “common wall”. This is unlike all other building classes where the separating wall is mentioned in the NCC as “common wall”.
- On the energy efficiency grounds, NCC is very strict and demanding toward class 1 buildings. Building fabric and glazing thermal performance that is required for a class 1 building are in some cases in excess by a factor of 2 comparing to a commercial building with the same floor area.
- Class 1a building can benefit from performance solutions like VURB or Energy Rating, however class 1b can only benefit from VURB and not the Energy Rating.
Class 2 building are apartments, where 2 or more owners/lessees/tenants live in. NCC suggests the term “sole-occupancy unit” for it and defines class 2 as a building that contains two or more sole- occupancy units. Generally, we expect a class 2 building to contain sole-occupancy units that are vertically aligned above and below each other.
- Apartments, separate dwellings above a common space.
- Although we expect that sole-occupancy units in a class 2 buildings to be vertically aligned, this certainly is not always a case. Separate dwellings that are above a common space (e.g. basement or carpark) form a class 2 building.
- Unlike class 1 buildings, there is no elemental provisions (i.e. DtS provisions) for class 2 buildings (with the exception of 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].
It’s better to define class 3 building with what it is not! Whenever a building doesn’t fit the categories of class 1a,1b,2 and 4, then it certainly is a class 3 building. Class 3 building is a common place providing a long-term or short-term accommodation for a number of unrelated people.
- Board house, guest house or hostel built for accommodation of more than 12 people or with floor area more than 300m2 (larger than the limits of class 1b)
- Backpackers accommodation, dormitory style accommodation
- Residential part of hotels, motels, schools, health care buildings or detention centres that can’t be specified as a class 4 building.
- 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 straight-forward 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.
- Considering wall-glazing construction, NCC is more demanding from class 3 compared to class 5 to 9 buildings (except of 9a and 9c ward) and less demanding compared to class 1a or 1b buildings. This also applies to roof and roof lights with respect to class 1a or 1b buildings.
- Section J verification method JV3 can be applied to class 3 building as a performance solution.
Class 4 is a sole dwelling in a 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”.
- 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.
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.
- 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.
- In addition to Section J verification method JV3 and Green Star, NABERS verification method can also be used for offices.
Class 6 building is a commercial building with a purpose of selling goods by retail or to provide services direct 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.
- Shop, mall, mart, retails, kiosk, showrooms.
- Restaurant, Café, bar, dining room.
- Hair dresser or barber shop, funeral parlour, service station, public laundry.
- Service stations excludes places where solely alterations happen; For example: carwashes, panel beating, auto electrical, tyre replacement or the like. These buildings are classified as class 8 buildings.
- There are some changes to the definition of a class 6 building in NSW and SA states.
Class 7 building is a storage-type building. This includes storage of the 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)
- Class 7a: Carparks
- Class 7b: Large storage sheds, warehouses, animal shelters
- Class 7 buildings may not be considered as part of building envelope and hence, provisions of energy efficiency may not be inclusive to these buildings. This is applicable in cases where class 7 part of a building is unconditioned (not occupied for business by people) and form a common wall with the rest of the building or located below the rest of the building.
- A carpark may be classified as 7a, 8 or 10a depending on the building size, purpose or occupancy.
Class 8 building is a process-type building. A factory or a 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.
- 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 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.
Class 9 building are of public nature or in another words, this building have a purpose to serve public with services that regards spiritual affairs, well-being, information or rather any other purpose for social gatherings.
Class 9a building – these building are generally 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 results 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.
- Class 9a: hospitals, ward areas, clinics, day surgery, 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 majorly 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 have 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.
The main characteristic of a class 10 building is that it is either a non-habitable building or simply a structure like antenna where 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 structure in an allotment where building is located in.
Class 10c building – is a private bushfire shelter that is not attached to class 1 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.
- Private garage is associated with a class 1 building. Garages that are associated with other types of buildings is private garage (class 10a) where 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.
- For the purpose of decreasing 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 garage floor area is great with comparison to the rest of the building and has minimum or no glazing.