NCC 2019 Volume One Amendment 1
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Section C Fire Resistance
Performance Requirements
CP1 Structural stability during a fire
A building must have elements which will, to the degree necessary, maintain structural stability during a fire appropriate to—
(a)
the function or use of the building; and
(b)
the fire load; and
(c)
the potential fire intensity; and
(d)
the fire hazard; and
(e)
the height of the building; and
(f)
its proximity to other property; and
(g)
any active fire safety systems installed in the building; and
(h)
the size of any fire compartment; and
(i)
fire brigade intervention; and
(j)
other elements they support; and
(k)
the evacuation time.
CP1 sets structural stability requirements for building elements during a fire.
CP1 does not make any reference to a fire-resistance level (FRL). FRLs are only included as part of the Deemed-to-Satisfy Provisions.
It may be found by a building proponent using an Alternate Performance Solution that FRLs to building elements are not necessary as other means, such as the use of active systems, satisfy the Performance Requirements.
“To the degree necessary”
CP1 uses the term “to the degree necessary”. This word usage is designed to provide flexibility in the way this provision is implemented. The intended meaning of the term “to the degree necessary” in CP1 and other Performance Requirements, is explained in explanatory information to A1.0(3)(c).
It means that the BCA recognises that different building elements require differing degrees of structural stability during a fire. The expression is intended to allow the appropriate authority to determine the degree of compliance necessary in each particular case.
Any decision made in this context can extend to not requiring an item to be installed or a particular level of performance to be achieved, if that is the appropriate action to be taken.
“Appropriate to”
The structural stability must be “appropriate to” the criteria listed in CP1, which relate to such factors as:
- the likelihood or risk of a fire occurring in the building;
- the load, intensity and potential danger of any fire in the building;
- the difficulty of evacuation and/or rescue;
- a structural element’s exposure to fire in another building, or risk of spreading a fire to another building;
- the fire safety systems in the building, which can affect the rate of fire spread (e.g. if a sprinkler system is installed in a building, it could either extinguish the fire or reduce its growth rate);
- the size of a fire and the difficulties in effecting an evacuation;
- the fire-fighting operations of the fire brigade; and
- the consequences of the failure of the element (another way of expressing this is to consider that if the element fails, could it result in the failure of another element).
- the time taken from the start of the emergency to the occupants reaching a safe place.
While assessment of a building proposal must have regard to the differing needs of each building element, the proposal must make sure that the elements have an appropriate structural stability during a fire so that:
- the fire does not endanger the occupants by entering escape routes; and
- the fire does not endanger firefighters while they are undertaking search and rescue operations.
Examples
Examples
The following are two examples of what may or may not be “appropriate”. They should not be regarded as absolute, or applicable in all circumstances.
Commercial poultry building
The building concerned is a commercial poultry building which is single storey and occupied by only a few workers, who are likely to know the building well. The building is situated a long distance from any other building and has direct routes to the exit doors.
In such a case, the building elements may not need to be fire protected under CP1 because the occupants would be able to evacuate quickly and if the building collapses, there is little likelihood of it damaging another building.
Note that for the example above, it is assumed that the building in question has not met the criteria to be considered a farm building or farm shed in the Deemed-to-Satisfy Provisions.
High-rise office building
The building concerned is a central city high-rise office building. It is located on the street alignment and close to other similar buildings. In such a case, the structural failure of any of the building elements could lead to danger to building occupants and the general public, failure of building elements intended to protect another building, or the collapse of another element which relies on the first element for structural support.
In this example, building elements may require a high level of protection under CP1.
In both cases, the ability of the fire brigade to control a fire also needs to be considered when considering the implications of CP1.
If the proposal being considered involves a solution that is taking advantage of the Deemed-to-Satisfy Provisions, the Deemed-to-Satisfy Provisions contain detailed requirements for the fire protection of building elements.
If a Performance Solution is being used, it may be appropriate to assess it using the Section C Deemed-to-Satisfy Provisions for guidance purposes. It is stressed, however, that compliance with the Deemed-to-Satisfy Provisions is not compulsory if alternative means can be found to satisfy the appropriate authority that the Performance Requirements will be achieved. The building proponent should refer to A2.2 for guidance on acceptable assessment methods for determining compliance with the Performance Requirements.
The Objective of this Section is to—
(a)
safeguard people from illness or injury due to a fire in a building; and
(b)
safeguard occupants from illness or injury while evacuating a building during a fire; and
(c)
facilitate the activities of emergency services personnel; and
(d)
avoid the spread of fire between buildings; and
(e)
protect other property from physical damage caused by structural failure of a building as a result of fire.
Basis of Objective
This Objective is based on the belief that a building should:
- provide people with an environment which, during a fire, will minimise the risk of them suffering illness or injury;
- provide people with an evacuation route which will minimise the risk of them suffering illness or injury while escaping a fire;
- facilitate the role of emergency services personnel, such as the fire brigade, if it becomes necessary for them to undertake such operations as fire-fighting and search and rescue;
- assist in minimising the risk of fire spreading from one building to another; and
- not have a structural failure during a fire that results in damage to another building, allotment or road.
There is a continuing debate regarding the means by which the BCA should minimise the risk of fire spreading from one building to another. Should the greater degree of fire protection be in the building on fire, or should it be in the building at potential risk of the fire spreading?
Generally, the BCA provisions aim to minimise the spread of fire from the building on fire, but there are some provisions that limit the spread of fire from an adjacent building.
Consequently, CO1(d) states that the spread of fire is to be avoided “between buildings”—that is, in either direction.
Protection of other propertyThe BCA is principally designed to maximise (within reasonable bounds) the safety, health and amenity of people in and around buildings. Protection of property, either the subject building or what is termed “other property”, is not generally a primary aim of the BCA—although it may sometimes be a consequence of the provisions of the BCA.
However, there are some exceptions to this rule, and the inclusion of “other property” in CO1(e) is one of these. In this context, a building is expected to maintain the level of structural sufficiency necessary to prevent it causing damage to any other property as a result of fire. The reason CO1(e) concerns itself with the protection of other property is primarily because fire from a building should not pose a serious risk to the health, safety and amenity of the public or occupants of another building. See Schedule 3 for definition of “other property”.
A building is to be constructed to maintain structural stability during fire to—
(a)
allow occupants time to evacuate safely; and
(b)
allow for fire brigade intervention; and
(c)
avoid damage to other property.
A building is to be provided with safeguards to prevent fire spread—
(a)
so that occupants have time to evacuate safely without being overcome by the effects of fire; and
(b)
to allow for fire brigade intervention; and
(c)
to sole-occupancy units providing sleeping accommodation; and
Application:
Application:
CF2(c) only applies to a Class 2 or 3 building or Class 4 part of a building.
(d)
to adjoining fire compartments; and
(e)
between buildings.
Structural stability
A building must remain structurally stable during a fire to:
- allow the occupants to safely evacuate;
- allow the fire brigade to undertake search and rescue,if necessary, and fire-fighting operations; and
- avoid damage to another building, allotment or road.
Instability may not contravene the BCA
So long as a building does not endanger life or other property, and the BCA’s structural stability criteria have been satisfied, then the building may become structurally unstable after a fire and still comply with the objectives of Section C. It could even collapse, provided none of the building falls in a way that endangers the public or causes damage to another building. For example, if a building falls onto a road, it could endanger the safety of the public and would therefore not achieve the Functional Statement.
Spread of fire
A building must have in-built safeguards to prevent the spread of fire:
- to allow sufficient time for the occupants to safely evacuate;
- to allow the fire brigade to undertake search and rescue,if necessary, and fire-fighting operations;
- in Class 2 or Class 3 buildings or Class 4 parts used as sole-occupancy units that provide sleeping accommodation to allow sufficient time for the occupants to safely evacuate;
- to an adjoining fire compartment; and
- from one building to another building.
Spread of fire may not contravene the BCA
So long as a building fire does not endanger life or other property, and the BCA’s spread of fire criteria have been satisfied, then the building may burn and still comply with the aims of Section C.
CP2 Spread of fire
(a)
A building must have elements which will, to the degree necessary, avoid the spread of fire—
(i)
to exits; and
(ii)
to sole-occupancy units and public corridors; and
Application:
Application:
CP2(a)(ii) only applies to a Class 2 or 3 building or Class 4 part of a building.
(iii)
between buildings; and
(iv)
in a building.
(b)
Avoidance of the spread of fire referred to in (a) must be appropriate to—
(i)
the function or use of the building; and
(ii)
the fire load; and
(iii)
the potential fire intensity; and
(iv)
the fire hazard; and
(v)
the number of storeys in the building; and
(vi)
its proximity to other property; and
(vii)
any active fire safety systems installed in the building; and
(viii)
the size of any fire compartment; and
(ix)
fire brigade intervention; and
(x)
other elements they support; and
(xi)
the evacuation time.
CP2 deals with the spread of fire both within and between buildings (including risk of spread of fire via the external walls of the building), and which does not only result from the structural failure of a building element.
CP2 does not make any reference to non-combustibility or a fire-resistance level (FRL). Non-combustibility and FRLs are only included as part of the Deemed-to-Satisfy Provisions. However, proponents of a Performance Solution should note these requirements, as part of developing the Performance Solution, if considered to be applicable. See CF2.
CP2(a)(i) aims to avoid a situation where fire either endangers occupants evacuating by way of exits, or impedes the capacity of emergency services personnel to access the building and fight the fire or rescue occupants.
CP2(a)(ii) aims to minimise the risk of people in Class 2 and Class 3 buildings and Class 4 parts, for example, if they were sleeping and consequently having difficulty escaping a fire. For this reason, CP2(a)(ii) requires that sole-occupancy units and corridors used for escaping be provided, to the degree necessary, with protection to avoid the spread of fire.
CP2(a)(iii) aims to minimise the risk of fire spreading from one building to another that could endanger the occupants of both buildings and impede the actions of the fire brigade. See CV1 and CV2 for two means of verifying, under certain circumstances, whether or not the requirements of CP2(a)(iii) will be achieved. Other assessment methods for determining compliance with the Performance Requirements are in A2.2.
CP2(a)(iv) aims to minimise the risk of fire spreading through a building that could endanger the occupants and impede the actions of the fire brigade. CP2(a)(iv) requires that a building must have elements that will avoid the spread of fire in a building. This includes avoiding the risk of fire spread via the external walls of the building. CP2(a)(iv) covers the risk of fire spread across the building facade due to the increased risk of spread to other compartments of the building, to other adjacent buildings, and the difficulty of firefighting external fires occurring at higher levels.
CP2(a) uses the term “to the degree necessary”. This word usage is designed to provide flexibility in the way this provision is implemented.
It means that the BCA recognises that different building elements require differing degrees of protection to avoid the spread of fire. The expression is intended to allow the appropriate authority to determine the degree of compliance necessary in each particular case after considering each building scenario.
Any decision made in this context can extend to not requiring an item to be installed or a particular level of performance to be achieved, if that is the appropriate action to be taken.
Building elements must be appropriate to avoid spread of fire, taking into consideration the matters listed in CP2(b) including:
- the likelihood or risk of a fire occurring in the building;
- the size, load or intensity of any fire in the building;
- the difficulty of evacuation and/or rescue;
- the building’s exposure to fire in another building, or risk of spreading a fire to another building;
- the fire safety systems in the building, which can affect the rate of fire spread (eg if a sprinkler system is installed in a building, it will either extinguish the fire or reduce its growth rate);
- the size of a fire and the difficulties in effecting an evacuation;
- the fire-fighting operations of the fire brigade and the resources available to it;
- the consequences of the failure of the element (another way of expressing this is to consider that if the element fails, could it result in the failure of another element); and
- the time taken from the start of the emergency to the occupants reaching a safe place.
If a Performance Solution is being used, it may be appropriate to assess it using the Section C Deemed-to-Satisfy Provisions for guidance purposes. It is stressed, however, that compliance with the Deemed-to-Satisfy Provisions is not compulsory if alternative means can be found to satisfy the appropriate authority that the Performance Requirements will be achieved. The building proponent should refer to A2.2 for guidance on acceptable assessment methods for determining compliance with the Performance Requirements.
Examples
Examples
The following are two very simple examples of what may or may not be “appropriate”. They should not be regarded as absolute or applicable in all circumstances.
Commercial poultry building
The building concerned is a commercial poultry building which is single storey and is occupied by only a few workers, who are likely to know the building well. The building is situated some distance from any other building and has direct routes to the exit doors.
In such a case, the building elements may not need to be protected against the spread of fire under CP2(a) because the building is:
- only one fire compartment;
- people are not sleeping in the building; and
- there is little likelihood of the spread of fire to another building because of the large distance to any other building.
Note that for the example above, it is assumed that the building in question has not met the criteria to be considered a farm building or farm shed in the Deemed-to-Satisfy Provisions.
High-rise office building
The building concerned is a central city high-rise office building. It is located on the street alignment and close to other similar buildings.
In such a case, the spread of a fire needs to be avoided because:
- the occupants will take some time to evacuate the building, so there is a need to protect the escape routes;
- there is a need for protection from the spread of a fire between each storey, including the risk of fire spread via the external walls of the building where each storey is a separate fire compartment; and
- a fire could easily spread between buildings because they are close together.
In this example, building elements may require a high level of protection against the spread of fire under CP2(a).
In both cases, the ability of the fire brigade to control a fire would also need to be considered when considering the implications of satisfying CP2(a).
If the proposal being considered involves a solution that is taking advantage of the Deemed-to-Satisfy Provisions, the Deemed-to-Satisfy Provisions contain detailed requirements for the fire protection of building elements.
CP3 Spread of fire and smoke in health and residential care buildings
A building must be protected from the spread of fire and smoke to allow sufficient time for the orderly evacuation of the building in an emergency.
Application:
Application:
CP3 only applies to—
- a patient care area of a Class 9a health-care building; and
- a Class 9c building.
CP3 deals with the spread of fire and smoke within a patient care area of a Class 9a building.
If a fire occurs in a health-care building, most patients would be unable to leave their beds, or may require assistance to evacuate the building. It is therefore important that the areas of the health-care building used by patients in beds be protected from fire in another part of the building.
See definition of “health-care building” in Schedule 3.
CP3 also applies in Class 9c buildings. In this case it applies throughout the whole building, not just in the resident use areas. This is because if a fire occurs in an aged care building, some residents would be unable to leave their beds, or may require assistance to evacuate the building.
CP4 Safe conditions for evacuation
To maintain tenable conditions during occupant evacuation, a material and an assembly must, to the degree necessary, resist the spread of fire and limit the generation of smoke and heat, and any toxic gases likely to be produced, appropriate to—
(a)
the evacuation time; and
(b)
the number, mobility and other characteristics of occupants; and
(c)
the function or use of the building; and
(d)
any active fire safety systems installed in the building.
Application:
Application:
CP4 applies to linings, materials and assemblies in a Class 2 to 9 building.
Fire hazard properties of materials
CP4 deals with the fire hazard properties of materials used in the construction of a building. These include such matters as their smoke, toxic gas and heat generation capacities.
CP4 uses the term “to the degree necessary”. This word usage is designed to provide flexibility in the way this provision is implemented.
It means that the BCA recognises that different materials and assemblies must resist the spread of fire to limit the generation of smoke, heat and toxic gases to differing degrees, depending on the circumstances of their use. The expression is intended to allow the appropriate authority to determine the degree of compliance necessary in each particular case after consideration of the building scenario.
Any decision made in this context can extend to not requiring an item to be installed or particular level of performance to be achieved, if that is the appropriate action to be taken.
The materials used in the building must be appropriate to avoid the spread of fire and the generation of smoke, heat and toxic gases after consideration of the matters listed in CP4. The reason for each of these matters is as follows:
- If the occupants can evacuate in a short time, then the smoke, heat and toxic gases generated prior to the completion of the evacuation will be less likely to have an impact on the safety of the occupants than if a longer evacuation time is required.
- The number, mobility and other characteristics of the occupants influence the time taken for the evacuation of the building. If the number of occupants is large, or they are not mobile, such as patients in a hospital or residents of an elderly people’s home, the evacuation time could be long. Such an evacuation time may allow the fire to develop and generate greater amounts of smoke, heat and toxic gases that will endanger the safety of the occupants trying to evacuate.
- The function or use of the building has an impact on the types of materials and linings that are part of the building’s fire load. This directly influences the rate of spread of any fire in the building.
- Any active fire safety system installed in the building, such as a sprinkler system, may limit the spread of fire and allow additional time for the evacuation of the occupants.
The Deemed-to-Satisfy Provision applicable to CP4 is C1.10. C1.10 limits the early fire hazard characteristics of materials susceptible to the effects of flame or heat, particularly during the early stages of a fire.
If a Performance Solution is being used, it may be appropriate to assess it using the Section C Deemed-to-Satisfy Provisions for guidance purposes. It is stressed, however, that compliance with the Deemed-to-Satisfy Provisions is not compulsory if alternative means can be found to satisfy the appropriate authority that the Performance Requirements will be achieved. The building proponent should refer to A2.2 for guidance on acceptable assessment methods for determining compliance with the Performance Requirements.
CP5 Behaviour of concrete external walls in a fire
A concrete external wall that could collapse as a complete panel (e.g. tilt-up and pre-cast concrete) must be designed so that in the event of fire within the building the likelihood of outward collapse is avoided.
Limitation:
CP5 is intended to overcome a problem observed when a fire has occurred in a building of “tilt-up construction”, and the panels have collapsed outwards, either during the fire or shortly after with little or no warning, endangering public safety, health, amenity and fire fighting operations.
A wide variety of structural systems and materials are possible to achieve this.
CP5 is only applicable to walls that could collapse as complete panels and, therefore, is not applicable to concrete and clay masonry walls, and the like, because such walls tend to fail in portions, rather than as complete panels.
The height limitation of 2 storeys is based upon the observation that the problem only seems to occur in low-rise buildings. This is due to taller buildings usually having fire rated floors and other building elements to restrain wall panels during a fire.
CP6 Fire protection of service equipment
A building must have elements, which will, to the degree necessary, avoid the spread of fire from service equipment having—
(a)
a high fire hazard; or
(b)
a potential for explosion resulting from a high fire hazard.
Certain types of equipment installed in buildings, such as boilers and the like, have a high fire potential. Other types of equipment, such as transformers and batteries, have a high potential for explosion. CP6 aims to minimise the risk of a fire spreading from such equipment to other parts of the building.
CP6 uses the term “to the degree necessary”. This word usage is designed to provide flexibility in the way this provision is implemented.
It means that the BCA recognises that different equipment requires differing levels of protection, depending on the circumstances within which it is used and installed. The expression is intended to allow the appropriate authority to determine the degree of compliance necessary in each particular case.
Any decision made in this context can extend to not requiring an item to be installed or a particular level of performance to be achieved, if that is the appropriate action to be taken.
CP7 Fire protection of emergency equipment
A building must have elements, which will, to the degree necessary, avoid the spread of fire so that emergency equipment provided in a building will continue to operate for a period of time necessary to ensure that the intended function of the equipment is maintained during a fire.
CP7 is intended to protect emergency equipment from the spread of fire within a building. It is important that emergency equipment continues to operate to the required level during an emergency. The length of time it should continue to operate will depend on the particular equipment.
Examples
Examples
CP7 requires that the emergency equipment continue to operate for as long as it is needed. Some examples of where protection may be required include:
- the protection of central smoke control plant required to operate in a fire for sufficient time for the occupants to evacuate; and
- the protection of the power supply to emergency lifts for sufficient time for the use of the lifts.
CP7 uses the term “to the degree necessary”. This word usage is designed to provide flexibility in the way this provision is implemented.
It means that the BCA recognises that different emergency equipment requires differing levels of protection, depending on the circumstances within which it is used and installed. The expression is intended to allow the appropriate authority to determine the degree of compliance necessary in each particular case.
Any decision made in this context can extend to not requiring an item to be installed or a particular level of performance to be achieved, if that is the appropriate action to be taken.
CP8 Fire protection of openings and penetrations
Any building element provided to resist the spread of fire must be protected, to the degree necessary, so that an adequate level of performance is maintained—
(a)
where openings, construction joints and the like occur; and
(b)
where penetrations occur for building services.
CP8 requires openings and penetrations in building elements to resist the spread of fire.
CP8 should be read in conjunction with CP2. CP8 deals with any opening or penetration within a building element, and CP2 deals with the building element itself.
CP8 uses the term “to the degree necessary”. This word usage is designed to provide flexibility in the way this provision is implemented.
It means that the BCA recognises that different building elements require differing levels of protection, depending on the circumstances within which they are used and installed. The expression is intended to allow the appropriate authority to determine the degree of compliance necessary in each particular case.
Any decision made in this context can extend to not requiring an item to be installed or a particular level of performance to be achieved, if that is the appropriate action to be taken.
CP9 Fire brigade access
Access must be provided to and around a building, to the degree necessary, for fire brigade vehicles and personnel to facilitate fire brigade intervention appropriate to—
(a)
the function or use of the building; and
(b)
the fire load; and
(c)
the potential fire intensity; and
(d)
the fire hazard; and
(e)
any active fire safety systems installed in the building; and
(f)
the size of any fire compartment.
The attending fire brigade must, in many cases, have access to and around a building during a fire, to undertake search and rescue and fire-fighting operations.
Access for the fire brigade should take into consideration such matters as:
- The size and type of the brigade vehicles likely to be required to fight a fire in the building. Consideration should be given to ensuring that the access is wide enough for a large fire truck, able to support the truck’s weight, and incorporate a suitable hard stand area if the brigade needs to use pump units to fight the fire.
- The need for the brigade to fight the fire, considering such factors as the size and type of the building, the nature of any fire safety systems in the building, and the contents of the building.
CP9 uses the term “to the degree necessary”. This word usage is designed to provide flexibility in the way this provision is implemented.
It means that the BCA recognises that buildings need different types of fire brigade access. These differences depend on the matters listed in CP9.
Any decision made in this context can extend to not requiring an item to be installed or a particular level of performance to be achieved, if that is the appropriate action to be taken.
Any access for the fire brigade must be appropriate to their needs and the type of vehicles and equipment to be used, having regard to the matters listed in CP9:
- the likelihood or risk of a fire occurring in the building;
- the size, load or intensity of any fire in the building; and
- the fire safety systems in the building, which can affect the rate of fire spread (eg if a sprinkler system is installed in a building, it will either extinguish the fire or reduce its growth rate).
Examples
Examples
The following examples indicate circumstances where fire brigade access may not be necessary:
- A small building, with a low level of occupancy and a low fire load may not require access.
- A building located in an area that does not have an operational fire service, or where the fire service is unlikely to reach the building during the course of a fire.
If the proposal being considered involves a solution that is taking advantage of the Deemed-to-Satisfy Provisions, the Deemed-to-Satisfy Provisions contain detailed requirements regarding fire brigade access.
If a Performance Solution is being used, it may be appropriate to assess it using the Section C Deemed-to-Satisfy Provisions for guidance purposes. It is stressed, however, that compliance with the Deemed-to-Satisfy Provisions is not compulsory if alternative means can be found to satisfy the appropriate authority that the Performance Requirements will be achieved. The building proponent should refer to A2.2 for guidance on acceptable assessment methods for determining compliance with the Performance Requirements.
CV1 Fire spread between buildings on adjoining allotments
Compliance with CP2(a)(iii) to avoid the spread of fire between buildings on adjoining allotments is verified when it is calculated that—
(a)
(b)
when located at the distances from the allotment boundary set out in Column 1 of Table CV1, a building is capable of withstanding the heat flux set out in Column 2 of Table CV1 without ignition.
Table CV1
|
Column 1 Location |
Column 2 Heat flux (kW/m 2 ) |
|
On boundary |
80 |
|
1 m from boundary |
40 |
|
3 m from boundary |
20 |
|
6 m from boundary |
10 |
CV1 is a means to verify whether or not a building proposal achieves the requirements of CP2(a)(iii) in minimising the risk of fire spreading between buildings on adjoining allotments. A fire in one building should not cause the spread of fire to another building, because such fire spread potentially endangers public safety, health and amenity.
It is not compulsory for a designer to use CV1. The designer has the choice of using:
- CV1 to verify that a proposal achieves CP2(a)(iii);
- the Deemed-to-Satisfy Provisions of Part C3; or
- another means of verifying that CP2(a)(iii) will be achieved.
If CV1 is used to calculate the level of heat flux, it is important to calculate the level at all the points referred to in Table CV1. The maximum level is not necessarily at the boundary. The size and shape of the openings will influence the level of heat flux.
Whether a material will ignite from radiant heat depends on the amount of heat and whether an ignition source (such as a spark) is present.
Examples
Examples
The following values give some typical examples of the amount of radiant heat necessary to ignite common materials used in buildings and their construction. Note, these figures should not be taken to be absolute, and may be subject to a range of variables.
-
Timber
- Ignition in the absence of a spark 35 kW/m2
- Ignition in the presence of a spark 20 kW/m2
-
Curtain materials
- Ignition in the absence of a spark 20 kW/m2
- Ignition in the presence of a spark 10 kW/m2
There are three mechanisms for transferring heat:
Conduction
Conduction is the transfer of heat from one source to the other when they are in contact.
Convection
Takes place when the flames or fire plume carry the heat to another body. Convection includes the carrying of embers from a burning body that can cause ignition of a second body.
Radiation
Radiation is the transfer of heat from one body to another. In essence this involves one body putting out enough heat to heat up another body without any form of contact, either directly or by way of flames or embers.
Radiation is the main mechanism for heat and fire spread between buildings.
By way of techniques developed in the field of physics, it is possible to calculate the amount of heat given off by a burning building. The answer depends on a number of factors, including:
- the distance from the building;
- the size and shape of the openings in the building;
- the temperature of the fire, which will depend on the:
- size of the fire, and
- type of materials burning; and
- the emissivity of any glass in openings in the building. The emissivity is, in comparatively simple terms, a measure of radiant heat reduction through a window opening. The maximum value is 1, but lower figures may be appropriate, depending on such factors as:
- whether the opening is drencher protected, or
- whether the opening is a fire window.
CV2 Fire spread between buildings on the same allotment
Compliance with CP2(a)(iii) to avoid the spread of fire between buildings on the same allotment is verified when it is calculated that a building—
(a)
is capable of withstanding the heat flux set out in Column 2 of Table CV2 without ignition; and
(b)
will not cause heat flux in excess of those set out in Column 2 of Table CV2,
when the distance between the buildings is as set out in Column 1 of Table CV2.
Table CV2
|
Column 1 Distance between buildings on the same allotment (m) |
Column 2 Heat flux (kW/m 2 ) |
|
0 |
80 |
|
2 |
40 |
|
6 |
20 |
|
12 |
10 |
CV2 is essentially the same as CV1, except that it deals with the spread of fire between two buildings on the same allotment.
It is not compulsory for a designer to use CV2. The designer has the choice of using:
- CV2 to verify that a proposal achieves CP2(a)(iii);
- the Deemed-to-Satisfy Provisions of Part C3; or
- another means of verifying that CP2(a)(iii) will be achieved.
The figures in Table CV2 are essentially the same as those in Table CV1, if an assumption is made that the boundary dividing the buildings to which Table CV1 is applied is half way between each building.
For further information on the use of CV2, refer to the comments on CV1.
CV3 Fire spread via external walls
Compliance with CP2 to avoid the spread of fire via the external wall of a building is verified when—
(a)
compliance with CP2(a)(iii) to avoid the spread of fire between buildings, where applicable, is verified in accordance with CV1 or CV2, as appropriate; and
(b)
the external wall system—
(i)
has been tested for external wall (EW) performance in accordance with AS 5113; and
(ii)
has achieved the classification EW; and
(iii)
if containing a cavity, incorporates cavity barriers and these cavity barriers have been included in the test performed under (i) at the perimeter of each floor; and
(c)
in a building of Type A construction, the building is protected throughout by a sprinkler system (other than a FPAA101D or FPAA101H system) complying with Specification E1.5 and has—
(i)
sprinkler protection to balconies, patios and terraces, and where overhead sprinkler coverage is not achieved alongside the external wall, sidewall sprinkler heads are provided at the external wall for the extent of the balcony, patio or terrace where overhead sprinkler coverage is not achieved; and
(ii)
for a building with an effective height greater than 25 m—
(A)
monitored stop valves provided at each floor level arranged to allow the isolation of the floor level containing the stop valve while maintaining protection to the remainder of the building; and
(B)
the sprinkler system being capable of providing sufficient flow to serve the design area required by AS 2118.1 for the relevant hazard class on each floor level plus the design area required by AS 2118.1 for the floor level above, except where the former level is—
(aa)
the floor level below the uppermost roof; or
(bb)
any floor level that is wholly below ground; and
(d)
in a building of Type B construction, the building is—
(i)
a Class 5, 6, 7 or 8 building or Class 4 part of a building; or
(ii)
a Class 2, 3 or 9 building that—
(A)
is protected throughout by a sprinkler system (other than a FPAA101D or FPAA101H system) complying with Specification E1.5; or
(B)
has any openings in external walls separated by a slab or other horizontal construction complying with C2.6(a)(iv) as if the building were of Type A construction.
CV3 is a means to verify whether or not a proposed external wall system achieves the requirements of CP2 in minimising the risk of fire spreading in a building and between buildings via the external walls of the subject building.
It is not compulsory for a designer to use CV3. The designer has the choice of using–
- CV3 to verify that a proposal achieves CP2;
- The relevant Deemed-to-Satisfy Provisions; or
- another means of verifying that CP2 will be achieved.
If CV3 is used, an external wall system must also be verified against CV1 and CV2, as well as meeting certain other fire safety measures, including ones specific to buildings of Type A and Type B construction.
Other fire safety measures are imposed in recognition that an external wall system tested to AS 5113 may contain combustible elements that still present a risk that needs to be mitigated in order to minimise the risk of fire spread via the external wall of a building.
The external wall system being tested to AS 5113 must reflect what is proposed to be installed, including cavities, cavity barriers, substrates and fixings. However, the external wall system being tested is not intended to include windows and doors.
The supplier or manufacturer of the system may provide a written declaration stating:
- The AS 5113 classification that the supplied system will achieve if installed correctly.
- the minimum design life of the system and any maintenance requirement to achieve the design life.
The installer may provide a written declaration that the installation has been carried out fully in accordance with the supplier's written instructions to achieve the required AS 5113 classification and design life.
CV4 Fire Safety Verification Method
Compliance with CP1, CP2, CP3, CP4, CP5, CP6, CP7, CP8 and CP9 is verified when a building is designed in accordance with Schedule 7.
The installer may provide a written declaration that the installation has been carried out fully in accordance with the supplier's written instructions to achieve the required AS 5113 classification and design life.
CV4 is a means to verify the fire safety of a building in order to meet the requirements of CP1, CP2, CP3, CP4, CP5, CP6, CP7, CP8 and CP9. For further guidance, refer to the ABCB Handbook for the Fire Safety Verification Method.