Part C2 Compartmentation and separation
C2.0 Deemed-to-Satisfy Provisions
for additional requirements for Class 9b buildings, Part H1; and
Where a solution is proposed to comply with the Deemed-to-Satisfy Provisions, C2.0 clarifies that for most buildings compliance with Parts C1, C2 and C3 will achieve compliance with CP1 to CP9. The exceptions to this general rule are set out below:
- If the building contains an atrium, it must comply with Part G3 in addition to Parts C1, C2 and C3.
- A building which comprises a theatre, stage or public hall must comply with Part H1 in addition to Parts C1, C2 and C3.
- If the building contains an atrium and one or more of a theatre, stage or public hall, it must comply with Parts C1, C2, C3, G3 and H1.
- Farm sheds must comply with Part H3 in addition to Parts C1, C2 and C3.
C2.1 Application of Part
To clarify that the floor area limitations of Part C2 do not apply to certain buildings.
The floor area limitations of Part C2 do not apply to a carpark containing a sprinkler system complying with Specification E1.5 (other than a FPAA101D or FPAA 101H system), an open-deck carpark or an open spectator stand.
The separation requirements of potentially explosive batteries from the rest of the building contained in C2.12(a)(v) do not apply to Class 8 electricity network substations. These batteries have inherent and specific protection, segregation and risk mitigation measures. They are housed within the substation, with other electrical equipment which the batteries are dedicated to support. The other ancillary building services in the substation are always kept separate from the batteries and further internal separation is not considered necessary.
C2.2 General floor area and volume limitations
Type A construction
|Type B construction||
Type C construction
|5, 9b or 9c||
Max —8 000 m2
Max volume—48 000 m3
Max —5 500 m2
Max volume—33 000 m3
Max —3 000 m2
max volume—18 000 m3
|6, 7, 8 or 9a (except for patient care areas)||
Max —5 000 m2
Max volume—30 000 m3
Max —3 500 m2
Max volume—21 000 m3
Max —2 000 m2
Max volume—12 000 m3
To limit the size of any fire in a building by limiting the size of the floor area and volume of a fire compartment.
Under C2.2(a) and Table C2.2, the allowable size of the fire compartment depends on two things. The first is the type of construction, which is a measure of a building’s ability to resist a fire. The second is the classification of the building, which is an indicator of a building’s potential fire load.
In the case of a Class 7 building which has an area of 3 000 m2, C2.2 enables three potential solutions. The building can be:
Under C2.2(b), machinery and plant rooms at the top of a building are not included in the calculation of a building’s floor area or volume of a fire compartment. The BCA assumes that such rooms represent a low risk to people in case of fire because of the generally:
- low fire load;
- low number of people who use them; and
- as the occupants of most buildings evacuate downwards, a fire in a plant room at the top of a building will generally not interfere with the ability to evacuate.
Under C2.2(c), in an atrium, the area of the atrium well above the floor of the atrium is excluded from the volume calculation because there is no space in which to store materials, thus it is assumed that it does not contribute to the fire load. See Part G3.
Table C2.2 allows sprinkler protected Class 9c buildings to have a maximum fire compartment size of—
- if the building is of Type A construction—8 000 m2; or
- if the building is of Type B construction—5 000 m2; or
- if the building is of Type C construction—3 000 m2.
C2.2 makes no reference to the use of Table C2.2 for a building containing mixed classifications. The table specifies both the maximum allowable floor area and volume of certain fire compartments and atria.
To calculate the maximum permissible floor area component of the size limitations in Table C2.2, firstly take the percentage of each classification as a proportion of the actual floor area of the building.
Then, use this percentage to calculate the proportion of the maximum floor area permitted for that classification in Table C2.2 and then add each of those calculations together to come to a maximum permitted floor area for the combined classifications. This is illustrated in simpler terms in the example below.
Figure C2.2 shows a building of Type C construction containing a factory (Class 8) with an office (Class 5) at the front. The total area of the building is 2 100 m2.
The area of the Class 8 portion of the building is 80% (1 680 m2) of the floor area of the whole building (that is, the combined Class 8 and Class 5 portions).
The area of the Class 5 portion of the building is 20% (420 m2) of the floor area of the whole building (that is, the combined Class 8 and Class 5 portions).
To determine if such a building complies with Table C2.2, the following calculations are necessary:
- Maximum area of Class 8 allowed by Table C2.2 = 2 000 m2
- The percentage of Class 8 is 80% = 80% of 2 000 m2 = 1 600 m2
- Maximum area of Class 5 allowed by Table C2.2 = 3 000 m2
- The percentage of Class 5 is 20% = 20% of 3 000 m2 = 600 m2
- Maximum allowable floor area = 1 600 + 600 = 2 200 m2
The maximum allowable floor area of the building is 2 200 m2. Therefore, the building in this example complies with the floor area component of Table C2.2. The fact that the Class 8 portion exceeds 1 600 m2 is irrelevant for the purposes of this process. However, that portion is not permitted to exceed 2 000 m2.
It should be noted that the maximum allowable volume must also be considered when determining whether the building complies with Table C2.2.
C2.3 Large isolated buildings
the building does not exceed 18 000 m2 in floor area nor exceed 108 000 m3 in volume, if—
To grant concessions for large isolated buildings from the floor area and volume limitations.
Under C2.3(a), a building with a floor area of 18 000 m2 or less and a volume of 108 000 m3 or less is permitted to have fire compartments which exceed the requirements of Table C2.2, if it complies with the requirements outlined below as applicable:
- Where the building is either Class 7 or Class 8—
- it contains no more than 2 storeys; and
- it has an 18 m wide open space around the building complying with C2.4(a).
- Where the building is Class 5–9 (including Class 7 and Class 8), it contains a sprinkler system complying with Specification E1.5 and has vehicular access complying with C2.4(b).
- it is protected with a sprinkler system complying with Specification E1.5; and
- it has vehicular access complying with C2.4(b).
C2.3 should be read in conjunction with the smoke hazard management systems required by Table E2.2a. The reason for this is that the smoke hazard management system will play an important part in occupant safety during a fire in large fire compartments.
Where there is more than one building on the allotment, each building may have fire compartments which exceed the requirements of Table C2.2, if each building complies with C2.3(a) or C2.3(b), or if the buildings are closer than 6 metres, they both must comply with C2.3(a) or C2.3(b), as applicable, as if they were one building.
C2.4 Requirements for open spaces and vehicular access
be wholly within the allotment except that any road, river, or public place adjoining the allotment, but not the farthest 6 m of it may be included; and
include vehicular access in accordance with (b); and
not be used for the storage or processing of materials; and
not be built upon, except for guard houses and service structures (such as electricity substations and pump houses) which may encroach upon the width of the space if they do not unduly impede fire-fighting at any part of the perimeter of the allotment or unduly add to the risk of spread of fire to any building on an adjoining allotment.
Vehicular access required by this Part—
must be capable of providing continuous access for emergency vehicles to enable travel in a forward direction from a public road around the entire building; and
must have a minimum unobstructed width of 6 m with no part of its furthest boundary more than 18 m from the building and in no part of the 6 m width be built upon or used for any purpose other than vehicular or pedestrian movement; and
must provide reasonable pedestrian access from the vehicular access to the building; and
must have a load bearing capacity and unobstructed height to permit the operation and passage of fire brigade vehicles; and
To set the minimum requirements for open space around a building and the provision of vehicular access for the fire brigade.
The reason for the open space requirement is to minimise the risk of a fire spreading to another building.
C2.4(a) specifies the compliance criteria for the open space required under C2.3. The open space must be wholly within the allotment. However, the open space may also include everything except what is beyond a line drawn six metres from the farthest edge of a road, river or public place adjoining the allotment.
The open space must also include the vehicular access required by C2.4(b), not be used for storage or processing and not be built on, except as specified.
This provision requires the making of a “performance-style” judgement. It is the responsibility of the building proponent to satisfy the appropriate authority that any buildings on the open space will not unduly impede the activities of the fire brigade, nor add to the risk of fire spreading to a building on an adjoining allotment.
The reason for the fire brigade vehicular access is to enable the brigade to intervene to fight the fire, assist with evacuation, and stop the spread of a fire to another building. The vehicular access also provides other emergency services personnel, such as ambulance officers, with the ability to access the building as necessary.
The required vehicular access must have access from the public road system (see C2.4(b)(i)) and must have the width, height and loadbearing capacity to allow the passage in a forward direction around the entire building and parking of fire brigade vehicles (see C2.4(b)(ii) and (iv)).
It must also have the necessary pedestrian access to the building (see C2.4(b)(iii)). This access may be from a public road which otherwise complies with the various requirements of C2.4(b) (see C2.4(b)(v)).
To achieve compliance with these provisions it is advisable to check with the local fire brigade, due to the varying sizes and type of equipment and vehicles that may be required to fight a fire.
C2.5 Class 9a and 9c buildings
A Class 9a health-care building must comply with the following:
The ancillary use areas referred to in (v) include, but are not limited to, the following:
A kitchen and related food preparation areas having a combined floor area of more than 30 m2.
A room containing a hyperbaric facility (pressure chamber).
A room used predominantly for the storage of medical records having a floor area of more than 10 m2.
A laundry, where items of equipment are of the type that are potential fire sources (e.g. gas fire dryers).
the floor above; or
a non-combustible roof covering; or
a ceiling having a resistance to the incipient spread of fire to the space above itself of not less than 60 minutes.
Other openings—construction having an FRL not less than –/60/–.
A Class 9c building must comply with the following:
A building must be divided into areas not more than 500 m2 by smoke-proof walls complying with Specification C2.5.
The ancillary use areas referred to in (iv) include, but are not limited to, the following:
A kitchen and related food preparation areas having a combined floor area of more than 30 m2.
A laundry, where items of equipment are of the type that are potential fire sources (e.g. gas fired dryers).
Storage rooms greater than 10 m2 used predominantly for the storage of administrative records.
To protect patients in a health-care building and residents in an aged care building from the spread of fire and smoke.
Residents or patients of Class 9a buildings are often unable to evacuate a building without assistance. They may be incapable of walking or bedridden. It is important to make sure that fire and smoke only affects small areas of the building.
C2.5(a)(i) requires compartmentation for the control of smoke and fire.
C2.5(a)(ii) and (v) make it necessary to separate potential sources of fire from any patient care area. C2.5(a)(ii) requires fire compartments in Class 9a buildings. An ancillary use area in C2.5(a)(v) is deemed to be an area where there are items of equipment or materials, that have a high potential fire hazard (high fire load or fire source).
C2.5(a)(iii) and (iv) require sub-compartmentation in certain areas to allow for the staged evacuation of patients from the building. Sub-compartmentation is considered to enhance evacuation procedures, which typically require assistance to be provided to evacuees by an adequate number of staff.
The requirements for smoke proof walls and doors are contained in Specification C2.5.
The first part of the figure shows how the administrative area of a hospital has been separated from the patient care area by a fire wall because the patient care area has a floor area of 2000 m2, the maximum permitted under C2.5(a)(i).
The second part of the figure shows how the ward area must be subdivided into areas with a maximum floor area of 1 000 m2 by a wall with an FRL of 60/60/60.
Compliance with C2.5(a)(iv)(B) may require a floor in a Class 9a building of Type B construction to have a fire-resistance level (FRL). The reason for this is that it is important to inhibit the spread of fire between floors. Separation of storeys in a Class 9a building also requires any openings in external walls to be vertically separated in accordance with C2.6.
Residents of Class 9c buildings are often unable to evacuate without assistance. They may be incapable of walking or bedridden. It is therefore important to make sure that fire and smoke only affects small areas of the building, hence allowing residents sufficient time should evacuation be necessary.
C2.5(b)(ii) requires certain walls and floors in Class 9c buildings to have a fire-resistance level (FRL). The reason for this is that it is important to inhibit the spread of fire for resident and occupant safety.
C2.5(b)(iii) allows internal walls (other than one bounding a lift or stair shaft) to have an FRL of 60/–/– because the floor is required to have an FRL of 60/60/60. Note that the FRL is only required for structural adequacy because Table 4 only requires loadbearing walls in these situations to have an FRL with respect to structural adequacy. The lower FRL allowed by C2.5(b)(iii) recognises the effectiveness of the required sprinkler systems in Class 9c buildings.
The compartmentation required by fire rated and smoke proof walls for Class 9c buildings is similar to that required for Class 9a buildings.
The required compartmentation and sub-compartmentation of Class 9c buildings are to allow for the staged evacuation of residents from the building. However, successful evacuation usually depends on assistance being provided to evacuees by an adequate number of staff. The BCA provisions for Class 9c buildings are based on minimal on duty on-site staff being available at any time.
C2.5(b)(i) requires a Class 9c building to be subdivided into areas with a maximum area of 500 m2 by smoke walls complying with Specification C2.5. No further subdivision of the fire compartments by smoke or fire rated walls is required. This recognises the benefits of sprinkler systems that must be installed in all Class 9c buildings.
An ancillary use area in C2.5(b)(iv) is deemed to be an area where there are items of equipment or materials that have a high potential fire hazard (high fire load or fire source). The reason these walls need only be smoke proof, whereas those in a Class 9a building must have an FRL, is that Class 9c buildings must be sprinkler protected.
C2.6 Vertical separation of openings in external walls
If in a building of Type A construction, any part of a window or other opening in an external wall is above another opening in the storey next below and its vertical projection falls no further than 450 mm outside the lower opening (measured horizontally), the openings must be separated by—
a spandrel which—
is not less than 900 mm in height; and
extends not less than 600 mm above the upper surface of the intervening floor; and
is of non-combustible material having an FRL of not less than 60/60/60; or
a slab or other horizontal construction that—
projects outwards from the external face of the wall not less than 1100 mm; and
extends along the wall not less than 450 mm beyond the openings concerned; and
is non-combustible and has an FRL of not less than 60/60/60.
The requirements of (a) do not apply to—
an open-deck carpark; or
an open spectator stand; or
a building which has a sprinkler system (other than a FPAA101D or FPAA101H system) complying with Specification E1.5 installed throughout; or
openings within the same stairway; or
To minimise the risk of fire spreading from one floor to another via openings in external walls in buildings of Type A construction.
C2.6 generally applies to buildings of Type A construction and Class 9a buildings of Type B construction, because they are the only buildings required to provide fire separation between floors. This separation is achieved by the floor being required to have a fire-resistance level (FRL). It applies to openings above one another in different storeys if they are within a horizontal distance of 450 mm of each other.
It does not apply to:
- sprinkler protected buildings because the sprinklers should prevent the fire developing to the stage where it could spread to the floor above;
- openings in a fire-isolated stair shaft. This is because the stair shaft is not considered to be separate storeys and it is assumed that fire spread between floors will not occur via the stairway; or
- open-deck carparks and open spectator stands. This is because it is unlikely that fire would spread between floors in these types of buildings as their open construction allows the dissipation of the effects of fire.
In addition, Class 9a buildings of Type B construction require openings in external walls to be vertically separated in accordance with C2.6 as if the building was Type A construction (see C2.5(a)(iv)). This can be achieved either by the construction methods outlined below or the installation of sprinklers in the building. The reason for this is that it is important to inhibit the spread of fire between floors in Class 9a buildings.
C2.6 requires the vertical separation of openings in external walls (see C2.6(a) and (b)) of buildings of Type A construction which do not have a sprinkler system complying with Specification E1.5 (other than a FPAA101D or FPAA101H system). The vertical separation of openings can be achieved by either of the following methods:
- a non-combustible spandrel or other non-combustible vertical construction having an overall height of 900 mm or more, extending at least 600 mm or more above the upper surface of the intervening floor, and having an FRL of 60/60/60 (see C2.6(a)(i)) as shown in Figure C2.6(1); or
- a non-combustible horizontal projection having an outwards projection from the external face of the wall of 1 100 mm or more, an extension along the wall beyond the openings of at least 450 mm, and having an FRL of 60/60/60 (see C2.6(a)(iv)) as shown in Figure C2.6(2).
If the external wall of the building is a glass curtain wall, C2.6(a)(iii) contains specific provisions to stop or limit the spread of fire and smoke between the glass and the edge of the concrete floor. The details are shown in Figure C2.6(3).
Although it could be argued that the spandrel or vertical projection should have the same FRL as the floor separating the storeys, this has not been found to be necessary.
C2.6(c) explains the meaning of the term "window or other opening" as used in C2.6(a). Basically, the term is used to describe a part of the external wall which does not have an FRL of at least 60/60/60 to limit the spread of fire from one storey to another by passing out through the window or opening and then re-entering the building through a similar opening (i.e. one without an FRL of at least 60/60/60) on the storey above. Examples of such openings include:
- glass curtain walls;
- non-fire rated panels; and
- other parts of the wall that do not have an FRL of at least 60/60/60.
C2.7 Separation by fire walls
Construction — A fire wall must be constructed in accordance with the following:
Separation of buildings — A part of a building separated from the remainder of the building by a fire wall may be treated as a separate building for the purposes of the Deemed-to-Satisfy Provisions of Sections C, D and E if it is constructed in accordance with (a) and the following:
The fire wall is carried through to the underside of the roof covering.
Where the roof of one of the adjoining parts is lower than the roof of the other part, the fire wall extends to the underside of—
the covering of the higher roof, or not less than 6 m above the covering of the lower roof; or
the lower roof if it has an FRL not less than that of the fire wall and no openings closer than 3 m to any wall above the lower roof; or
Separation of fire compartments — A part of a building separated from the remainder of the building by a fire wall may be treated as a separate fire compartment if it is constructed in accordance with (a) and the fire wall extends to the underside of—
the roof covering.
To explain that buildings separated by a fire wall may be considered as fire compartments or be regarded as separate buildings.
C2.7(a) outlines how a fire wall is to be constructed.
C2.7(a)(i) sets out the required FRL of a fire wall. If any part adjoining the fire wall is required to have a higher FRL, the fire wall must achieve the higher FRL. The exception occurs if an adjoining part is an open-deck or sprinklered carpark that complies with the concessions set out in Table 3.9, 4.2 or 5.2 of Specification C1.
- C3.5 for doorways in fire walls;
- C3.6 for sliding doors in fire walls;
- C3.7 if the fire wall forms separation required for horizontal exits; and
- C3.15 for openings for service penetrations.
C2.7(a)(iii) indicates which building elements are permitted to pass through or cross a fire wall and prohibits the use of any building element if it reduces the fire wall's FRL below that required. Hence, elements that pass through or cross a fire wall have to be part of the fire wall's tested prototype.
C2.7(a)(iii) grants an exemption to its requirements for small roof battens and roof sarking.
The fire wall must extend through all storeys and similar spaces which are common to the subject parts of the building, and any adjoining part of the building, through to the underside of any roof covering (see C2.7(b)(ii)).
C2.7(b) outlines the requirements for the extent of a fire wall that separates adjoining parts of a building where the roofs are at different levels.
If buildings, with different roof levels divided by a fire wall, are to be treated as two separate buildings, the fire wall must extend up to the underside of the highest roof or not less than 6 m above the covering of the lowest roof.
Alternatively, C2.7(b) allows the fire wall not to extend 6 m above the lower roof if the roof to the lower level building:
- has the FRL prescribed for the fire wall by Specification C1.1 and no openings are located within 3 m of any wall located above the lower roof; or
- the lower roof is non-combustible and the part of the building below has a sprinkler system complying with Specification E1.5 (other than a FPAA101D or FPAA101H system) installed.
For a fire wall to compartment a building it must extend to the underside of any roof covering or between floors that have an equivalent FRL to the fire wall.
If the building is being separated into fire compartments by a fire wall have different roof levels there is no requirement to extend the fire wall to the underside of the higher roof level or above the lower roof level. This is because the fire wall serves as a means to limit the floor area of the building. When a fire wall is applied in this case, the building cannot be treated as two separate buildings for the purpose of Sections C, D and E of the BCA.
Figure C2.7(2) illustrates the case where two fire walls divide storeys but do not align, therefore not meeting the requirements of C2.7(b). In this case, the building cannot be regarded as two buildings divided by a fire wall.
Figure C2.7(3) illustrates a circumstance where a fire wall can be an external wall. This is important to note because of a possible reading of the definition of “fire wall” which indicates that a fire wall would always be an internal wall. For the purposes of Sections C, D and E, the separated building is regarded as two buildings.
C2.8 Separation of classifications in the same storey
If a building has parts of different classifications located alongside one another in the same storey—
To minimise the risk of a fire in one classification on a storey causing the failure of building elements in another classification on the same storey.
The fire-resistance level (FRL) required for building elements varies, depending on the expected fire load. This load is measured in the BCA by the building classification. With these differing FRLs, it is important that a fire in one classification does not cause the failure of building elements in any other classification.
There are two options to stop a fire spreading from one classification to another classification on the same storey:
- use the highest of the two fire-resistance levels (FRLs) required for each building element in that storey (see C2.8(a)); or
- place a fire wall between the two different classifications (see C2.8(b) and (c)). In a building of mixed classification C2.8(b) clarifies that for Type A and Type B construction the FRL is the higher of that specified in Table 3 or 4 but for Type C construction it is the FRL specified in Table 5. This is because the FRL for firewalls in Type C construction is the same for all Classes.
Figure C2.8(1) illustrates some examples of fire walls separating different classifications within the same storey of a building. In the first diagram, the public corridor must be fire-separated from the Class 6 part (as shown) or the Class 5 part to achieve total fire-separation between the different classifications. If a doorway is located in the fire wall, it must comply with C3.5.
The diagrams in Figure C2.8(2) illustrate examples of fire walls separating different classifications within the same storey of a multi-storey building and floors separating different classifications.
C2.9 Separation of classifications in different storeys
If parts of different classification are situated one above the other in adjoining storeys they must be separated as follows:
Type B or C construction — If one of the adjoining parts is of Class 2, 3 or 4, the floor separating the part from the storey below must—
be a floor/ceiling system incorporating a ceiling which has a resistance to the incipient spread of fire to the space above itself of not less than 60 minutes; or
have an FRL of at least 30/30/30; or
To minimise the risk of a fire in one classification causing the failure of building elements in another classification in a different storey.
C2.9 specifies the required separation between parts of a building which are of a different classification, situated one above the other.
The aim of C2.9 is for the fire load of a storey to determine the fire protection of the floor above it. A fire on one storey will affect the storey above to a greater degree than any storey below.
C2.9(a) sets out the requirements for buildings of Type A construction. Figure C2.9 illustrates an example of the required fire-resistance level (FRL) of floors in a 3 storey building required to be of Type A construction.
C2.9(b) sets out the requirements for buildings of Type B and Type C construction. However, note that C2.9(b ) is only applicable where one of the parts being separated is Class 2, Class 3 or Class 4 and Specification C1.1 Clauses 4.1(i) and 5.1(e) require floors to be protected if the building is Class 2, 3 or 9.
C2.10 Separation of lift shafts
Any lift connecting more than 2 storeys, or more than 3 storeys if the building is sprinklered, (other than lifts which are wholly within an atrium) must be separated from the remainder of the building by enclosure in a shaft in which—
Any lift in a patient care area in a Class 9a health-care building or a resident use area in Class 9c building must be separated from the remainder of the building by a shaft having an FRL of not less than—
in a building of Type A or B construction — 120/120/120; or
in a building of Type C construction — 60/60/60.
To minimise the risk of a fire spreading from one floor to another floor of a building by way of a lift opening.
The approach adopted in C2.10 for lift shafts is similar to that adopted by the BCA for stairway shafts.
C2.10 applies to all classes of buildings and specifies the protection requirements for openings both for lift landing doors and services.
In any building required to be of Type A or B construction, having a lift connecting more than 2 storeys or more than 3 storeys if the building is sprinklered (other than lifts that are wholly within an atrium), the lift must be in an enclosed shaft separated from the rest of the building.
The lift shaft walls in a building of Type A construction must have the relevant fire-resistance level (FRL) prescribed by Table 3 of Specification C1.1. It does not matter what Class the building is, nor whether the shaft walls are loadbearing.
In a building required to be of Type B construction, the lift shaft walls must have the relevant FRL prescribed by Table 4 of Specification C1.1 if they are loadbearing. If the lift shaft walls are non-loadbearing they must be of non-combustible construction.
As all emergency lifts are required to be fire separated from the remainder of the building, C2.10(c) clarifies that the lift shaft is to have an FRL of not less than 120/120/120.
C2.10(d) only applies to fire-isolated lift shafts. Lift landing doors and indicator panels are covered by C3.10. Openings for other services must comply with any other appropriate provisions in Part C3.
If a lift is wholly in an atrium, it is not required to be in a fire-isolated shaft. This is because the atrium comprises a single fire compartment.
Any lift in a patient care area in a Class 9a building, or a resident use area in a Class 9c building is to be in a fire-isolated shaft. In a Class 9a or 9c building that is required to be of Type A or B construction it is to have an FRL of 120/120/120. In a Class 9a or 9c building of Type C construction the shaft is to have an FRL of 60/60/60.
Apart from emergency lifts and lifts in patient care and resident use areas, lifts need not be in a fire-isolated shaft if the building is of Type C construction. This is because such buildings are not required to have fire-rated floors or any fire compartmentation between storeys.
C2.11 Stairways and lifts in one shaft
To maintain a safe evacuation route for people using a fire-isolated stairway, by separating the stairway shaft from the lift shaft.
Lift shafts do not offer the same fire protection to occupants as fire-isolated stairway shafts. This is because lift landing doors to shafts have no insulation properties and do not seal against smoke to the same extent as fire doors to stairway shafts. Also, many lift over-runs are places where rubbish or other combustible materials may accumulate and are therefore potential fire-sources.
C2.12 Separation of equipment
lift motors and lift control panels; or
emergency generators used to sustain emergency equipment operating in the emergency mode; or
central smoke control plant; or
a battery system installed in the building that has a total voltage of 12 volts or more and a storage capacity of 200 kWh or more.
Equipment need not be separated in accordance with (a) if the equipment comprises—
smoke control exhaust fans located in the air stream which are constructed for high temperature operation in accordance with Specification E2.2b; or
stair pressurising equipment installed in compliance with the relevant provisions of AS 1668.1; or
a lift installation without a machine-room; or
equipment otherwise adequately separated from the remainder of the building.
Separation of on-site fire pumps must comply with the requirements of AS 2419.1.
Separating construction must have—
when separating a lift shaft and lift motor room, an FRL not less than 120/–/–.
To limit the spread of fire from service equipment having a high fire hazard or potential for explosion and to ensure emergency equipment continues to operate during a fire.
The types of equipment referred to in C2.12(a)(i) and (ii) and C2.12(c) need to continue to operate during an emergency, such as a fire. It is therefore important to stop the spread of fire to this equipment.
The type of equipment referred to in C2.12(a)(iv) have a high explosive potential. The high temperatures and pressures associated with a boiler requires consideration for protection as opposed to a normal water heater. It is important that any fire in this type of equipment does not spread to other parts of the building.
Batteries referred to in C2.12(a)(v) have the potential to contain high levels of embodied energy. In a fire event, this embodied energy can contribute to fire propagation and can be difficult to extinguish. Reference to “installed in the building” means batteries hard wired into the building. This includes batteries used to provide power supply for fire safety equipment, lifts, pumps, energy storage from renewable energy sources and the like. It does not include batteries associated with removable data infrastructure, vehicles or batteries that can be readily removed or relocated (such as plug in UPS batteries).
Not all equipment is required to be protected. Examples are listed in C2.12(b). This equipment is either designed to withstand high temperatures during a fire, or is required to be protected by other parts of the BCA.
Under C2.12(d), the minimum fire-resistance level (FRL) for construction used to separate the equipment listed in C2.12(a) from the remainder of the building is 120/120/120, with –/120/30 fire doors. However, if Specification C1.1 (particularly Tables 3, 4 or 5) requires a higher FRL, then that higher FRL applies.
C2.13 Electricity supply system
An electricity substation located within a building must—
be separated from any other part of the building by construction having an FRL of not less than 120/120/120; and
have any doorway in that construction protected with a self-closing fire door having an FRL of not less than –/120/30.
A main switchboard located within the building which sustains emergency equipment operating in the emergency mode must—
be separated from any other part of the building by construction having an FRL of not less than 120/120/120; and
have any doorway in that construction protected with a self-closing fire door having an FRL of not less than –/120/30.
Electrical conductors located within a building that supply—
a substation located within the building which supplies a main switchboard covered by (b); or
a main switchboard covered by (b),
have a classification in accordance with AS/NZS 3013 of not less than—
if located in a position that could be subject to damage by motor vehicles — WS53W; or
otherwise — WS52W; or
be enclosed or otherwise protected by construction having an FRL of not less than 120/120/120.
Where emergency equipment is required in a building, all switchboards in the electrical installation, which sustain the electricity supply to the emergency equipment, must be constructed so that emergency equipment switchgear is separated from non-emergency equipment switchgear by metal partitions designed to minimise the spread of a fault from the non-emergency equipment switchgear.
For the purposes of (d), emergency equipment includes but is not limited to the following:
Fire hydrant booster pumps.
Pumps for automatic sprinkler systems, water spray, chemical fluid suppression systems or the like.
Pumps for fire hose reels where such pumps and fire hose reels form the sole means of fire protection in the building.
Air handling systems designed to exhaust and control the spread of fire and smoke.
Control and indicating equipment.
Emergency warning and intercom systems.
To limit the spread of fire from electrical equipment and to enable the uninterrupted operation of emergency equipment during a fire.
Certain types of electrical equipment have a high potential for explosion as well as fire. C2.13(a) requires that the doorways to sub-stations be protected with –/120/30 fire doors to avoid the spread of any fire from the electrical equipment.
Some State and Territory authorities may have additional requirements for the construction of electricity sub-stations. See relevant State or Territory Appendix to the BCA.
To enable the required emergency equipment to continue to operate during any emergency, the following must be achieved:
- The main switchboard referred to in C2.13(b) must be separated from other parts of the building by construction having a fire-resistance level (FRL) of 120/120/120, and any door openings protected with –/120/30 fire doors.
- The electrical conductors referred to in C2.13(c) must comply with the appropriate sections of AS/NZS 3013—Wiring installations—Wiring systems for specific applications, or be protected by fire rated construction with an FRL of 120/120/120.
Emergency equipment is considered sustained by a main switchboard when the emergency equipment does not rely on:
- battery backup; or
- an alternative power source running through the main switchboard,
when operating in the emergency mode.
ABCB funded research determined that providing physical segregation between non-emergency equipment switchgear and emergency equipment switchgear reduces the impact of potential damage from fire by 40%. It is essential that this equipment continue to operate during a fire. C2.13(d) therefore requires the emergency equipment to be segregated from the other equipment in all switchboards by metal partitions designed to prevent the spread of any fault from the non-emergency equipment to the emergency equipment.
C2.14 Public corridors in Class 2 and 3 buildings
To minimise the risk of long public corridors in Class 2 and Class 3 buildings becoming smoke logged.
In a building fire, certain people are subject to greater risks than others, for example, the very young, elderly, people with disabilities, and those who are asleep.
In a Class 2 or Class 3 building there is a very high risk that building occupants will be asleep when a fire occurs. It is important that they be able to safely evacuate the building. To assist in the safe evacuation, long public corridors should not become smoke logged.
C2.14 therefore requires the division of the public corridors into 40 metre lengths, by smoke walls and smoke doors. The details of the smoke walls are set out in Specification C2.5, and details for the smoke doors are set out in Specification C3.4.
The measurement of the length of the public corridor includes the sum of all connected corridor lengths that are continuous within a separate storey, smoke compartment or fire compartment.