Building Classes and the Format of the BCA

The BCA is split into two volumes. Volume One deals with buildings in Classes 2 to 9 and Volume Two, also known as the Housing Provisions, deals with buildings of Class 1 and 10.

Volume One
Volume One is split into nine sections with the first section containing administrative provisions, the remainder containing technical provisions.

Volume One of the BCA is structured so that each technical section contains:

• Objectives – a statement that is considered to reflect community expectations
• Functional Statements – statements of how a building achieves the objective
• Performance Requirements – the level of performance a building solution must meet (i.e. the minimum standard)
• Building Solutions – the way in which the performance requirements are met. The solution may be one that complies with the Deemed to Satisfy provisions or an alternate solution or a combination of both. The Deemed to Satisfy provisions are the ‘black and white’ solutions and if followed ensure compliance with the performance requirements. Alternate solutions allow for innovative design and use of materials and normally require certification by an expert in the particular field.

Section A: General Provisions
Contains information such as definitions, how buildings are to be classified and the list of guidance documents such as Australian Standards that have been referenced by the BCA as Deemed to Satisfy solutions.

Section B: Structure
Requirements for the structural stability of the building including the structural resistance that materials and forms of construction must achieve against effects such as dampness, termites, water penetration, etc.

Section C: Fire Resistance
Requirements for the fire resistance of the building. This is to ensure that not only fire spread from one building to another is prevented but also a building maintains structural stability during a fire to allow for occupants to evacuate and the fire brigade to fight the fire. This is achieved by separation distances between buildings, fire protection to external walls (including any openings such as windows) and the splitting up of the internal spaces of the building into separated compartments. It is important to understand the following terminology in relation to this section:

• Type of Construction – not to be confused with building class, this determines the level of fire resistance particular elements of the building must achieve. There are three types of construction, namely A, B and C, which are determined by the building’s class and rise in storeys. Type A includes buildings that have a higher risk such as high rise, high occupant buildings and is therefore the most fire resistant. Type C includes buildings that have a lower risk and is therefore the least fire resistant.
• Fire Source Feature – this represents the potential location that fire may spread from or to. It is normally the external wall of another building on the same lot, a side or rear boundary or the far boundary of a road adjoining the lot. Boundaries are regarded as fire source features because the owner of one lot has no control over what is built on adjoining lots and there is potential for a building to be built up to the boundary on the adjoining lot.
• Fire-Resistance Level (FRL) – measured in minutes, this is the resistance to the passage of fire an element of a building achieves. It consists of the criteria structural adequacy, integrity and insulation. For example, a 90/30/60 FRL represents an element that must achieve a fire resistance level of 90 minutes for structural adequacy, 30 minutes for integrity and 60 minutes for insulation.
• Sole Occupancy Unit – this means a room or part of a building for occupation by one occupant to the exclusion of others.

Section D: Access & Egress
Provisions relating to the number, size, type, and separation of emergency exits, as well as the distance to an emergency exit. These provisions are determined by the building’s class, size of the building and the number of persons the building accommodates. The section also includes provisions relating to the accessibility of a building for people with disabilities.

Section E: Services & Equipment
This section identifies the fire safety equipment that must be installed in a building. This equipment includes firefighting equipment (e.g. fire hydrants, hose reels, portable fire extinguishers, etc), smoke hazard management (e.g. smoke detectors and alarms) and emergency lighting and signs. The section also provides the requirements for lift installations when one is installed in a building. As a general rule all buildings require portable fire extinguishers to be installed. The provision of any other equipment is dependant on the size of the building.

Section F: Health & Amenity
The requirements for damp & weatherproofing, sanitary facilities, room sizes, light and ventilation and sound insulation. The number of sanitary facilities is dependant on the number of people the building accommodates. Provisions relating to sanitary facilities for people with disabilities are also included in this section. The light and ventilation provision relates to both natural as well as artificial lighting and ventilation. Not all buildings are required to be provided with natural ventilation or lighting.

Section G: Ancillary Provisions
This section contains requirements that affect structures that are ancillary to the main use of the building including minor structures (swimming pools, vaults, cool rooms), heating appliances (fireplaces, flues, and chimneys) and atrium construction. It also contains requirements for buildings constructed in alpine areas and bush fire prone areas.

Section H: Special Use Buildings
The requirements specific to certain buildings such as theatres and public halls.

Section I: Maintenance
The requirements for the maintenance of equipment in buildings.

Volume Two
Volume Two is split into three sections, the first section containing administrative provisions, the second the performance provisions and the third the acceptable construction provisions.

Section 1: General Provisions
This contains information such as definitions, how buildings are to be classified and the list of guidance documents such as Australian Standards that have been referenced by the BCA as Deemed to Satisfy solutions.

Section 2: Performance Provisions
This section is further split into five subsections entitled Structure, Damp & Weatherproofing, Fire Safety, Health & Amenity and Safe Movement and Access. Within each subsection the objectives, functional statements and performance requirements are stated.

Section 3: Acceptable Construction
This section, also known as the Acceptable Construction Manual, contains the Deemed to Satisfy building solutions for Class 1 and 10 buildings. The section is split into 11 subsections, namely Site Preparation, Footings & Slabs, Masonry, Framing, Roof & Wall Cladding, Glazing, Fire Safety, Health & Amenity, Safe Movement and Access, Additional Construction Requirements and Structural Design Manuals.

The Building Code of Australia classifies a building or a part of a building by the purpose for which it is designed, constructed, or adapted to be used.

Here is an overview of how buildings with multiple dwellings within are classified.

Class 2 Buildings
Class 2 buildings contain two or more sole-occupancy units each being a separate dwelling. The occupancy and use of the separate units should be similar to a house and because the residents are permanent and related, they will be familiar with the building and have a degree of control over, and vested interest in, what happens within the unit.

Apartments are class 2 buildings.

Concessions Applying to class 2 Buildings
Disability Access
There are no access or facility requirements for people with a disability.

Energy Efficiency
There are less stringent requirements based on the assumption that buildings will be used as permanent dwellings and that the occupants will pay the electricity bills.

Fire Safety
• Self-contained smoke alarms are permitted with no requirement for a full smoke detection system
• No requirement for a fire alarm monitoring system connected to a fire station dispatch centre (unless fire sprinklers are required)
• Additional exit sign exemptions
• Sound and intercom systems for emergency purposes are not required unless the building is more than 25 metres high.

Class 3 Buildings
Class 3 buildings are residential buildings, other than a class 1 or 2, which are a common place of long term or transient living for a number of unrelated people. The fact that the people are unrelated is very important for distinguishing them from class 1 or 2 buildings.

Class 3 buildings have separate sole-occupancy units that are not intended to be occupied and used on a permanent basis by related people. Some examples of class 3 buildings include:
• a boarding-house
• guest house
• hostel
• lodging-house
• backpackers’ accommodation
• residential part of a hotel or motel
• residential parts of schools

Mixed Classification Buildings
A number of different arrangements for apartment living are now available in the marketplace. In some buildings a number of units are permanently occupied by the owners and the remainder are available for short term accommodation. In this situation the mix can often change, and it may be impractical to separate the building into class 2 and class 3 parts.

To provide the desired flexibility in the buildings use it should be classified for both class 2 and 3 in accordance with Clause A3.4 of the Building Code of Australia. This means that the building and units must be fully compliant for both classifications.

Serviced Apartments
It would be possible for a building to contain serviced apartments in which the occupants of each unit are permanent residents and related to one another. In such a case it would be a class 2 building.

However, it is more likely that a building with serviced apartments (either wholly or in part) will be operated like a hotel where apartments will be available for short term accommodation by unrelated people. In these instances the building should either have dual classifications (2 and 3) or just class 3 if all of the apartments will be available.

Where a building is described by the applicant as being either class 2 or serviced apartments, a building surveyor should query the nature of the intended use and if the apartments will be available for short term accommodation by unrelated people, then the building must be classified as class 3.