NCC Tutor lesson - Understanding Building Classifications

Building Classifications 

[voice over] Understanding building classifications: NCC Tutor 

Slide 1:  

The focus of this presentation is building classifications, which are essential to understanding and using the NCC correctly. There is one set of building classifications in the NCC, and they are used in all three Volumes. 

You have probably referred to different building classifications as you go about your work, or you have heard others talking about them, for example you might have spoken about whether a building was a Class 1a building or a Class 1b building, or perhaps you have discussed whether a particular kind of building met the requirements for a Class 6 building.  

This module is best viewed with a copy of the NCC on-hand. To access the NCC visit, abcb.gov.au and register or log in to freely access it.  

Most of the requirements in the NCC apply to a specific classification, or specific classifications of buildings. 

Slide 2:  

In order to do so you will need to be able to identify where to find information about building classifications. 

You will need to identify the 10 building classifications in the NCC. 

You will need to identify building classifications for mixed use buildings and buildings with more than one classification. 

And you will also need to find out and know about how to get a determination about a building’s classification where it is unclear. 

Slide 3:  

The first question we need to answer in order to find and use the NCC building classifications: 

Is where can we find information on the different building classifications in the three volumes of the NCC? 

Building classifications are in Part A6 of the Governing Requirements in each of the three volumes.  

The text is identical in all three Volumes.  

If you know or have read information on building classifications in one Volume, then you know or have read what it says in the other Volumes as well.  

Part A6 contains the formal definitions of each building classification, and some explanatory information, which discusses the distinctions between the classifications and also gives lots of useful examples. 

The Building classifications handout is also another handy resource. It contains more explanations and examples that can be helpful as well, especially when trying to distinguish between 2 possible classifications.  

It is available from the ABCB website. 

Slide 4:  

Buildings are built to serve different purposes, so the way that they are designed and constructed also varies. Therefore, the requirements that they must meet also varies, in terms of things like size, space, facilities, light, as well as how you enter them and exit them, things like fire safety as well as structural strength.  

Building classifications within the NCC reflect this variation in the purpose of different buildings, and the Performance Requirements that they must meet. 

Let’s consider a few examples: 

• Firstly, a single family home versus an apartment block versus a backpacker hostel versus a hotel. We might sleep, relax and otherwise live in all of these, but a single family home would not successfully fill the purpose of a hotel or backpacker hostel, nor would it make for comfortable accommodation for multiple families. 

• An office block versus a warehouse versus a factory, versus a small retail shopfront. People might work in all of these buildings, but the work they are doing varies along with the number of people who might work in each one, the number of visitors we might get, and the other materials we might keep in the space. A typical office block would make an inconvenient warehouse and a warehouse would be an uncomfortable office or shopfront, in most instances. 

Because buildings have different purposes, they also need to perform differently, as a structure. They will be different sizes and shapes, they will need different numbers, sizes and shapes of rooms, they will need different amounts of light and warmth, and will need different facilities, such as bathrooms, electrical connections and lifts. They will vary in their energy and water use, their requirements for safety and security, including ways to get in and out of the buildings, and they will vary by their need to resist fire and their structural strength. 

Let’s consider another few examples, particularly in relation to a safe evacuation: 

Firstly, a single storey shop or a retail building versus a multi-storey office block. Any door or window in a single storey shop may be able to be used for escape from a fire or another hazard, so there are often multiple routes for evacuation. The same is not true though, in a multi-storey building, where the windows are usually not able to be used for evacuation (particularly if they are above ground level). This means that dedicated escape paths (usually the fire stairs) are needed in multi-storey buildings, but not usually in single-storey buildings. The number of people who are likely to be in each of these buildings is also very different, resulting in different requirements for services to suppress a fire in order to allow time for people to escape. 

Lets look at another example; 

A hospital versus a school hall. Facilities such as these, are required to allow for safe evacuation of people. The requirements would be different in each of these two buildings, because of the assumption that a significant number of people in a hospital might have difficulty evacuating on their own (because of their injuries of illnesses). They may not be able to walk, may not be able to use stairs or may not be able to move without bringing equipment with them.  

A school by comparison, might be a primary school. It might be full of school aged children and it might not be as easy to evacuate children as it is to evacuate adults. We can make the assumption that most of the children will be able to walk out of the building without assistance although if they’re children they may need direction or shepherding by adults to get out. 

The NCC manages this variation in building purpose and requirements by grouping buildings by their function and by their use, assigning a classification to each grouping, and specifying particular Performance Requirements for particular classifications of buildings. 

On this slide we can see that there is a number of different classifications of buildings. 

Buildings are classified in Classes 2, 3, 4, 5, 6, 7, 7a, 7b, Class 8 and Class 9 is divided into Class 9a, b and c. These tend to be considered to be commercial buildings and are covered in Volume One of the NCC.  

In Volume Two, we have Classes 1a and 1b, as well as Classes 10a, 10b and 10c. These are often referred to as residential buildings.  

The separation between these two is not particularly hard and fast. In particular there are some disability access provisions that are contained within Volume One that may also apply to Class 1b buildings, which are otherwise covered in Volume Two.  

The NCC building classifications are not intended to cover every possible structure that might be built, just those common buildings covered in the NCC itself. Some types of less commonly built structures that are not covered by the provisions are for example; power plants, water treatment plants, bridges or dams.  

Different legislation in each State and Territory often regulates the construction of these types of structures.  

Slide 5:  

How well do you know the different building classifications? 

Descriptions of the building classifications and the Explanatory information are contained in Part A6 of the Governing Requirements of any Volume of the NCC. This is the definitive, legal statement of what each class of building covers. If you are in doubt, you should use these descriptions over any other information. 

The ABCB Building classifications handout, that we discussed earlier, can be downloaded from the ABCB website (abcb.gov.au). The handout contains a clear summary of all the different classifications along with some tips for distinguishing different classes of buildings. 

Slide 6:  

Now let’s test your knowledge of building classes.  

What class of building is a: 

Hardware store? 

A furniture factory? 

A mosque? 

Or A bed and breakfast? 

Take a moment and write down what class you think each of these buildings is.  

Hardware Store Class 6

Furniture factory Class 8

Mosque Class 9b

Bed and breakfast Class 1b

Slide 7:  

Here’s some more to test your knowledge. 

What class of building is a: 

Kindergarten? 

Shearers hut? 

Multi-story carpark? 

Residential care facility? 

Write down your answers as to what class you believe each of these buildings is. 

Kindergarten? Class 9b

Shearers’ hut? Class 3

Multi-storey carpark? Class 7a

Residential care facility? Class 9c

Slide 8: 

Which of the following is a Class 1a building? Is a Class 1a: 

• A single, detached dwelling above a single garage for that dwelling? 

• Is an apartment complex a Class 1a building? 

• What about a row of terrace houses, with common fire walls between them, each with an attached garage? 

• Or perhaps a three storey building with a shared underground garage and a residential sole occupancy unit on each storey, not including the garage. 

Take a moment to consider which are the correct answers (There is more than one answer).  

The Class 1a buildings are:

A single, detached dwelling above a single garage for that dwelling and

A row of terrace houses, with common fire walls between them, each with an attached garage.

Slide 9:  

Which class is each of the following buildings? 

• Accommodation for visiting doctors in a rural hospital. 

• Six single dwellings on one block that are used for holiday stays. 

• A row of terrace houses, with common fire walls between them, and a common underground garage. 

• And finally, a caretaker’s flat in a warehouse or office building. 

Take a moment to consider what the correct classification is for each of these buildings.  

• Accommodation for visiting doctors in a rural hospital – Class 3
• Six single dwellings on one block that are used for holiday stays – Class 1b
• A row of terrace houses, with common fire walls between them, and a common underground garage – Class 2
• A caretaker’s flat in a warehouse or office building – Class 4 part of a building

Slide 10: 

So far in this presentation we have looked at Volume One and we know that this covers Class 2 to Class 9 Buildings. We have also examined Volume Two and this covers Class 1 and Class 10 buildings. But what about Volume Three? 

Volume Three of the NCC covers plumbing and drainage requirements for all building classifications.  

Slide 11:

We have many buildings that are considered to be mixed-use buildings. That is, its a building that contains different components each of which has a different building classification. In the example here we have a building that contains apartments which would be Class 2, shops which is Class 6 and a carpark which is Class 7a. 

Each building part of the building is classified separately according to its purpose. 

Each part must meet all the Performance Requirements for its particular classification. 

Generally, if a part of a building that has a different purpose is less than 10% of the total floor area of the storey it is on, then it is not given a separate classification. The classification of the rest of the building, or space it is within, applies. 

So some examples. 

In a single storey warehouse with an office that is 15% of the total floorspace (remember this is only single storey), the office space has a separate classification – Class 5 – and that office space must meet the Performance Requirements for a Class 5 building.  

• If the office space was smaller and only 5% of the total floorspace, then it would be classified, along with the rest of the warehouse, as Class7b, and would need to meet Class 7b Requirements. 

• If the warehouse had 2 storeys and the office was larger,  15% of the area on the ground floor was office, but only 7.5% of the total floorspace, then the office space would still be considered a Class 5 part of the building, because it is the percentage of the floorspace on each storey it is on that matters, not the total percentage across the entire building. 

There are some instances where the 10% rule doesn’t apply. The 10 percent rule doesn’t apply to Laboratories. A lab is usually a Class 8 building and it is considered to have a high fire risk which must be appropriately managed. Treating a laboratory like any other class of building would potentially mean that a fire hazard management measure that might be inadequate for the risk the laboratory could pose risk to other users of the building. 

The ten percent rule also doesn’t apply to a sole-occupancy unit in a Class 2 or 3 building or a Class 4 part of a building. When any space is used for people to live in, the NCC mandates Performance Requirements to manage fire risks and ensure adequate sound insulation. Treating an SOU like another class of building would mean reducing these requirements, which would mean in a living space that failed to comply with requirements and lacked necessary amenities. 

More discussion of the 10% rule and exceptions can be found in the Explanatory information in Part A6 of any Volume of the NCC. 

Slide 12:  

Here’s some examples to test your knowledge of classifications in mixed-use buildings. 

Firstly, a shopping centre with shops in the ground floor and 2 floors of car parking above. Retail shops would be Class 6 and the carpark would be considered Class 7a. 

The next is a church with an attached priest’s residence. The church would be Class 9b and the residence would be a Class 4 part of a building. 

Next is a hospital with a child care centre. The hospital is a health care building so would be considered a Class 9a. The childcare centre is considered an assembly building so would be considered to be a Class 9b. 

The last one. A boiler room or machinery room in the basement carpark of an office building. This would be considered a Class 7a as there is no special classification needed for a boiler room or machinery room regardless of the size or percentage of the floor space. HOWEVER, there are specific Performance Requirements for the construction of these kinds of rooms, for example fire separation requirements. 

It is important that you see Volume one of the specific Performance Requirements for this type of building.  

Slide 13:  

A question that often comes up is: Can a whole building have multiple classifications? 

Yes, the answer is that it is possible if the building is designed to serve multiple purposes. 

So for example, the building owner or developer might want to be able to sell or rent the units in the building for a variety of purposes. That might be office space for small businesses in which case they would be a Class 5 building. It could be retail space for businesses that sell to the public in which case it would be a Class 6. Or it might be something that’s use as a storage space in which case it will be a Class 7b. 

This is permissible but the building must meet all the requirements for any class and the most stringent requirements of all the classes must apply. 

For example, a storage space might not need to have a lot in the way of facilities, such as bathrooms, because typically few people work in these types of spaces.  

However, an office or retail space might require a minimum number of bathrooms (determined by the expected number of users and size) because there is an expectation that some people will typically spend long periods of time in the space, and that a larger number of people will use the space.  

Therefore, units would need to meet the more stringent facility requirements for Class 5 and Class 6 buildings. 

Slide 14: 

Another question that often comes up is: What if a building’s classification isn’t obvious? 

If the most appropriate classification for a building is note clear, the appropriate authority must classify the building as belonging to the class it most closely resembles. 

The appropriate authority “means the relevant authority within the statutory responsibility to determine the particular matter”. As per NCC Schedule 3, Definitions, which are the same in any Volume. 

It is important to understand that Building classification is a risk management issue. The risk associated with a building’s intended purpose needs to be assessed so that the building can be classified appropriately and built to meet the most appropriate Performance Requirements. 

When deciding on a building’s classification, the appropriate authority reviews the building proposal and might consider the: 

• Intended purpose of the building, and/or different parts of the building. 

• They might consider the building classification that the building most closely resembles. 

• The likely fire load of the building. 

• Likely risks to the safety, health and amenity of the people who might use the building. 

• Also relevant decisions and determinations by appeals courts in the relevant state or territory.  

The definition of appropriate authority is slightly different in NSW. 

Some building regulatory authorities in some states and territories issue their own guidelines for building classification.  

A building surveyor is one of the main appropriate authorities to classify a building, but it could also be a council and that this should be confirmed with the local regulator. 

One thing to research and to consider is who is the most appropriate authority in the State or Territory that you may work. Generally it is the body that provides the building applications or approves the building applications. 

The body must approve a buildings classification including when different parts of the building have different classifications and when a space or a whole building has multiple classifications.  

But you would not want to wait to submit a full application before getting an indication of the suitability of a buildings classification.  If there is any uncertainty it is always useful to get an indication of what that classification is likely to be before completing full sets of plans and completing the building application.  

Slide 15: 

So how would you classify the following example; it’s a retail shop with a residence at the back.  

• Retail building = Class 6
• Residence = Class 4 part of a building

Slide 16:  

How would you classify this building? A building that could be used as a warehouse or for light industrial activities. 

• Both Class 7a and Class 8

Slide 17:  

How would you classify this building? A building with squash courts, a small sports association office, and a café taking up 30% of the building. 

• Sports centre = Class 9b
• Café = Class 6
• Office = Class 9b (<10% of floor area)

Slide 18:  

What classes are the following buildings: 

• A Pottery studio? 

• A Service station? 

• A Railway station? 

• Or a Warehouse? 

• A Pottery studio – Class 8
• A Service station – Class 6
• A Railway station – Class 9b
• Warehouse – Class 7b

It is important to also note that a service station is considered to be Class 6. But a car repair workshop, for example a car mechanic, a panel beater or a tyre replacement place is likely to be considered a Class 8. 

Slide 19: 

True or false? 

You are building a small hostel (Class 1b) on the coast. You can find all the relevant Performance Requirements in Volume Two of the NCC. 

False. Yes, that’s right. You need to refer to Volume Three for plumbing and drainage provisions. Also, some of the disability access and fire provisions in Volume One may apply to a Class 1b building.

Slide 20:  

A boarding house or hostel could be a Class 1b building or a Class 3 building. What key factors determines its class? 

Would it be the Height in storeys? A Class 3 building is typically a high-rise building while a Class 1b building is typically a low-rise building. 

Would it be who will live or stay there? A Class 3 building is designed to accommodate unrelated people while a Class 1b building may accommodate related or unrelated people. 

Or maybe it’s how many people it can accommodate and total floor area? A Class 1b building would normally not accommodate more than 12 people and would have a total floor area of no more than 300 m2.  If bigger than this, it would be classed as a Class 3 building. 

Yes, that’s right. A Class 1b building would normally not accommodate more than 12 people and would have a total floor area of no more than 300m².

Slide 21:  

True or false? 

A Class 1a residence cannot be built over or under another building or structure of any other Class, except for a private garage. 

True. Yes the statement is true. If a residence is built over any other type of structure it would be a sole occupancy unit of a Class 2 building. This is the case, even if the other structure is a common garage space.

Slide 22:  

The key points to take away from this presentation are: 

Building classifications are found in the Governing Requirements, Part A6 in all three Volumes of the NCC. 

A mixed use building may have parts that have different classifications and the “10% rule” usually applies. 

An entire building can have more than one classification, if it is designed or intended for more than one potential purpose. 

And finally, if building classification is unclear, refer to the appropriate authority in the relevant state or territory. 

This brings us to the end of the presentation. Thank you for viewing this NCC Tutor module. Check out the other NCC Tutor modules to build your understanding of the NCC.