Specification C1.1 Fire-Resisting Construction

NCC 2016 Volume One

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Specification C1.1 Fire-Resisting Construction

1. Scope

This Specification contains requirements for the fire-resisting construction of building elements.

Intent

To clarify that Specification C1.1 contains requirements for fire-resisting construction of building elements.

Note that applies only to the Deemed-to-Satisfy Provisions of the BCA. If a Performance Solution is used to satisfy a Performance Requirement, it is not necessary to comply with .

Parts , , , , , , and of the BCA also contain requirements for building elements to be fire-resisting and to have a fire-resistance level (FRL).

2. General Requirements

2.1 Exposure to fire-source features

(a)

A part of a building element is exposed to a fire-source feature if any of the horizontal straight lines between that part and the fire-source feature, or vertical projection of the feature, is not obstructed by another part of the building that—

(i)

has an FRL of not less than 30/–/–; and

(ii)

is neither transparent nor translucent.

(b)

A part of a building element is not exposed to a fire-source feature if the fire-source feature is—

(i)

an external wall of another building that stands on the allotment and the part concerned is more than 15 m above the highest part of that external wall; or

(ii)

a side or rear boundary of the allotment and the part concerned is below the level of the finished ground at every relevant part of the boundary concerned.

(c)

If various distances apply for different parts of a building element—

(i)

the entire element must have the FRL applicable to that part having the least distance between itself and the relevant fire-source feature; or

(ii)

each part of the element must have the FRL applicable according to its individual distance from the relevant fire-source feature,

but this provision does not override or permit any exemption from Clause 2.2.

2.2 Fire protection for a support of another part

(a)

Where a part of a building required to have an FRL depends upon direct vertical or lateral support from another part to maintain its FRL, that supporting part, subject to (b), must—

(i)

have an FRL not less than that required by other provisions of this Specification; and

(ii)

if located within the same fire compartment as the part it supports have an FRL in respect of structural adequacy the greater of that required—

(A)

for the supporting part itself; and

(B)

for the part it supports; and

(iii)

be non-combustible—

(A)

if required by other provisions of this Specification; or

(B)

if the part it supports is required to be non-combustible.

(b)

The following building elements need not comply with (a)(ii) and (a)(iii)(B):

(i)

An element providing lateral support to an external wall complying with Clause 5.1(b) or C1.11.

(ii)

An element providing support within a carpark and complying with Clause 3.9, 4.2 or 5.2.

(iii)

A roof providing lateral support in a building—

(A)

of Type A construction if it complies with Clause 3.5(a), (b) or (d); and

(B)

of Type B and C construction.

(iv)

A column providing lateral support to a wall where the column complies with Clause 2.5(a) and (b).

(v)

An element providing lateral support to a fire wall or fire-resisting wall, provided the wall is supported on both sides and failure of the element on one side does not affect the fire performance of the wall.

2.3 Lintels

A lintel must have the FRL required for the part of the building in which it is situated, unless it does not contribute to the support of a fire door, fire window or fire shutter, and—

(a)

it spans an opening in—

(i)

a wall of a building containing only one storey; or

(ii)

a non-loadbearing wall of a Class 2 or 3 building; or

(b)

it spans an opening in masonry which is not more than 150 mm thick and—

(i)

not more than 3 m wide if the masonry is non-loadbearing; or

(ii)

not more than 1.8 m wide if the masonry is loadbearing and part of a solid wall or one of the leaves of a cavity wall.

2.4 Method of attachment not to reduce the fire-resistance of building elements

The method of attaching or installing a finish, lining, ancillary element or service installation to a building element must not reduce the fire-resistance of that element to below that required.

2.5 General concessions

(a)

Steel columns — A steel column, other than one in a fire wall or common wall, need not have an FRL in a building that contains—

(i)

only 1 storey; or

(ii)

2 storeys in some of its parts and 1 storey only in its remaining parts if the sum of the floor areas of the upper storeys of its 2 storey parts does not exceed the lesser of—

(A)

1/8 of the sum of the floor areas of the 1 storey parts; or

(B)

in the case of a building to which one of the maximum floor areas specified in Table C2.2 is applicable — 1/10 of that area; or

(C)

in the case of a building to which two or more of the maximum floor areas specified in Table C2.2 is applicable — 1/10 of the lesser of those areas.

(b)

Timber columns — A timber column may be used in a single storey building if—

(i)

in a fire wall or common wall the column has an FRL not less than that listed in the appropriate Table 3, 4 or 5; and

(ii)

in any other case where the column is required to have an FRL in accordance with Table 3, 4 or 5, it has an FRL of not less than 30/–/–.

(c)

Structures on roofs — A non-combustible structure situated on a roof need not comply with the other provisions of this Specification if it only contains—

(i)

lift motor equipment; or

(ii)

one or more of the following:

(A)

Hot water or other water tanks.

(B)

Ventilating ductwork, ventilating fans and their motors.

(C)

Air-conditioning chillers.

(D)

Window cleaning equipment.

(E)

Other service units that are non-combustible and do not contain flammable or combustible liquids or gases.

(d)

Curtain walls and panel walls — A requirement for an external wall to have an FRL does not apply to a curtain wall or panel wall which is of non-combustible construction and fully protected by automatic external wall-wetting sprinklers.

(e)

* * * * *

(f)

Balconies and verandahs — A balcony, verandah or the like and any incorporated supporting part, which is attached to or forms part of a building, need not comply with Tables 3, 4 and 5 if—

(i)

it does not form part of the only path of travel to a required exit from the building; and

(ii)

in Type A construction—

(A)

it is situated not more than 2 storeys above the lowest storey providing direct egress to a road or open space; and

(B)

any supporting columns are of non-combustible construction.

2.6 Mezzanine floors: Concession

(a)

This Clause does not apply to a Class 9b building that is a spectator stand or audience viewing area accommodating more than 100 persons as calculated according to D1.13.

(b)

A mezzanine and its supports need not have an FRL or be non-combustible provided—

(i)

the total floor area of all the mezzanines in the same room does not exceed 1/3 of the floor area of the room or 200 m², whichever is the lesser; and

(ii)

the FRL of each wall and column that supports any other part of the building within 6 m of the mezzanine is increased by the amount listed in Table 2.6.

Table 2.6 INCREASED FRLs — CONSTRUCTION SURROUNDING MEZZANINES

Level otherwise required for any FRL criterion (mins)	Increase in level to (not less than):
30	60
60	90
90	120
120	180
180	240
Note: The increase in level applies to each FRL criterion (structural adequacy, integrity or insulation) relevant to the building element concerned.

2.7 Enclosure of shafts

Shafts required to have an FRL must be enclosed at the top and bottom by construction having an FRL not less than that required for the walls of a non-loadbearing shaft in the same building, except that these provisions need not apply to—

(a)

the top of a shaft extending beyond the roof covering, other than one enclosing a fire-isolated stairway or ramp; or

(b)

the bottom of a shaft if it is non-combustible and laid directly on the ground.

2.8 Carparks in Class 2 and 3 buildings

(a)

If a Class 2 building contains not more than 4 storeys of which—

(i)

one storey is Class 7 used solely for the purpose of parking motor vehicles or for some other purpose that is ancillary to a Class 2; and

(ii)

the remaining storeys are of Class 2,

the carpark storey is regarded as Class 2 only for the purpose of determining the relevant fire-resisting requirements of this Specification.

(b)

If a Class 3 building or a building of Class 2 and 3 contains not more than 3 storeys of which—

(i)

one storey is Class 7 used solely for the purpose of parking motor vehicles or for some other purpose that is ancillary to the other storeys; and

(ii)

the remaining storeys are of Class 2 or 3,

the carpark storey is regarded as Class 2 or 3 only for the purpose of determining the relevant fire-resisting requirements of this Specification.

2.9 Residential aged care building: Concession

(a)

In a Class 3 building protected with a sprinkler system complying with Specification E1.5 and used as a residential aged care building, any FRL criterion prescribed in Tables 3, 4 or 5—

(i)

for any floor and any loadbearing wall, may be reduced to 60, except any FRL criterion of 90 for an external wall must be maintained when tested from the outside; and

(ii)

for any non-loadbearing internal wall, need not apply if—

(A)

it is lined on each side with standard grade plasterboard not less than 13 mm thick or similar non-combustible material; and

(B)

it extends—

(aa)

to the underside of the floor next above; or

(bb)

to the underside of a ceiling lined with standard grade plasterboard not less than 13 mm thick or a material with at least an equivalent level of fire protection; or

(cc)

to the underside of a non-combustible roof covering; and

(C)

any insulation installed in the cavity of the wall is non-combustible; and

(D)

any construction joint, space or the like between the top of the wall and the floor, ceiling or roof is smoke sealed with intumescent putty or other suitable material.

(b)

The concession described at (a) does not apply to fire-protected timber building elements.

2.1

Exposure to fire-source features

Intent

To define how a building element may be exposed to a fire-source feature.

Fire-source feature

Refer to the definition in on the term “fire-source feature”.

A fire-source feature is a possible fire-source external to the building from which fire could spread into the building. It may be an allotment boundary or another building on the allotment from which fire could spread to the subject building.

does not consider a building element to be exposed to a fire-source feature if it is shielded from the fire-source feature by another part of the building which:

has an FRL of 30/–/– or more, and is not transparent or translucent;
is less than 15 metres above another building on the allotment. Parts of a building more than 15 metres above another building are not deemed to be affected by fire; or
is below the level of the finished ground at every relevant part of a side or rear boundary.

illustrates some of the exemptions from the exposure to a fire-source feature.

Figure Spec C1.1(1)

PART OF A BUILDING NOT EXPOSED TO A FIRE-SOURCE FEATURE

The building element must have an FRL required for the closest part of the element exposed to the fire-source feature (see ).

Alternatively, the building element may have a varying FRL according to the individual distance of each section of the building element from the fire-source feature (see ).

illustrates the alternatives for an external loadbearing wall of a Class 5 building required to be of Type A construction.

2.2

Fire protection for a support of another part

Intent

To minimise the risk that a building element required to have a fire-resistance level (FRL) will fail during a fire due to the failure of another element required to give it vertical or lateral support.

Support of building elements with an FRL

sets out the requirements for the fire protection of building elements that provide lateral or vertical support to another building element. This is because a building element with an FRL is usually dependent on the support to maintain its FRL.

Accordingly, does not apply to elements that support ceilings required to have a fire-protective covering or a resistance to the incipient spread of fire. Nor to an element required to be non-combustible.

Exceptions of building elements

lists a number of exemptions to and .

The lateral support for the types of wall referred to in is considered unnecessary in these cases, because allows the use of brick veneer walls, and enables the prevention of outward collapse of certain external walls by specifying the connection of panels to the building's frame.

The inherent fire resistance of the supports included in , and is considered adequate in the carparks covered by each clause. It should be noted that compliance with the relevant Table is necessary in order to comply with the relevant clause.

exempts roofs providing lateral support to other building elements. This is because of a concession within for Type A construction. In addition, there is no requirement for Type B and C construction, principally because such buildings are generally low rise.

exempts certain columns, as listed in , from having an FRL.

Under a fire wall or fire-resisting wall referred to should not collapse because it is supported by another building element on the other side of the wall.

Figure Spec C1.1(2)

PLAN SHOWING ALTERNATIVE METHODS OF COMPLYING WITH TABLE 3

2.3

Lintels

Intent

To minimise the risk that the failure of a lintel over an opening in a wall required to have a fire-resistance level (FRL) will result in the failure of the wall during a fire.

A lintel must have the same FRL as the part of the building containing it. This is unless it does not contribute to the support of a fire door, fire window or fire shutter. Otherwise, the failure of the lintel during a fire could cause the collapse of all, or part, of the wall.

only applies to a lintel required by the Deemed-to-Satisfy Provisions to have an FRL.

and contain some concessions for small openings where the failure of the lintel would not result in a major collapse of the wall and lead to the spread of fire to another building.

2.4

Method of attachment not to reduce the fire-resistance of building elements

Intent

To minimise the risk that the method of attaching or installing a finish, lining, ancillary element or service installation will compromise the fire-resistance of a building element.

Clause 2.4 prohibits a required FRL of a building part from being reduced by the attachment or installation of facings, finishes, ancillary elements or the installation of ducting or any other service.

The reason for controlling this is due to the potential for changes to the fire performance of a building element via attaching or installing another element.

2.5

General concessions

Intent

To permit the use of certain building practices known to provide acceptable levels of fire safety.

The concessions contained in allow a steel column to not have an FRL in one and, in some cases, two storey buildings.

The basis for this concession is the low rise of such buildings. In many cases, the columns form the legs of a portal frame, with the roof being non-fire rated. In such a case, there would be little benefit in fire rating the column when the roof beams are not rated.

Because of the importance of the structural integrity of a common wall or fire wall in limiting the spread of fire, the concession for steel columns providing lateral support does not apply.

The concessions contained in permit a reduced FRL in timber columns in single storey buildings. One method of determining the FRL of a timber column is to use the charring rate of the type of timber in the column.

The structures on a roof referred to in are not likely to lead to the spread of fire, especially as they are required to be non-combustible. The intent of is to specify that the concession does not apply to structures that contain units that in turn contain flammable or combustible liquids and gases.

The curtain walls referred to in must be non-combustible and protected by an external wall-wetting sprinkler system. When such construction is used, protection is provided from fire spreading to the subject building. For the term “curtain wall”, see . For the purposes of this provision, glass is regarded as non-combustible.

Balconies, verandahs and the like do not generally add a significant fire load to a building. Therefore, they are not required to be in compliance with , or . This is provided that occupants are not put at risk during an evacuation because the only means of egress is by way of the balcony, verandah or the like.

Also, if the building is of Type A construction, the balcony, verandah or the like must be situated at a low level of the building, and have non-combustible supports.

2.6

Mezzanine floors: Concession

Intent

To provide concessions for small mezzanines.

The Clause 2.6 concession does not apply to certain Class 9b buildings, as specified in . The concession only applies to certain small mezzanines, as specified in .

If it complies with the conditions specified in , a mezzanine and its support may be constructed from materials that do not have an FRL and/or are combustible.

requires an increase in each FRL criterion of each wall or column that supports any other part of the building, and is within 6 metres of the mezzanine. There is no case in which a building element, with an increased fire rating, requires an FRL greater than 240 minutes.

Increasing the FRLs surrounding a mezzanine which is combustible, or which does not have an FRL, recognises the increased fire load that exists within both the mezzanine and the storey as a whole. This recognises the fire load limiting effect of the minimum area requirement in .

2.7

Enclosure of shafts

Intent

To minimise compromising the fire-resisting performance of a shaft.

Shaft enclosures required to be fire-resisting must be completely fire-separated from all other portions of the building by building elements that have the appropriate fire-resistance.

complements other requirements for the walls of shafts by requiring that shafts be enclosed at the top and bottom by fire rated construction.

grants exemptions for the top and bottom of shafts in cases where the likelihood of fire entering the shaft is unlikely. This occurs when the top of the shaft is the top of the building (see ), or the bottom of the shaft is laid on the ground (see ).

2.8

Carparks in Class 2 and 3 buildings

Intent

To allow the use of residential levels of fire protection to be used for carparks in certain Class 2 and Class 3 buildings.

classifies a storey used for carparking as Class 7. The fire risks of a single storey carpark in a low-rise Class 2 or Class 3 building are not as substantial as they are in other carparks attached to other classifications, so a concession is suitable. This concession is based upon the assumption that the carpark associated with the Class 2 or 3 building will be for the exclusive use of the building occupants and that the carpark would represent a low fire risk.

The sole purpose of this concession is to allow the carpark and/or ancillary use storey to be regarded as a Class 2 or Class 3 building, as applicable, for the purposes of determining the fire resistance requirements of .

This concession applies to buildings which are otherwise wholly Class 2, wholly Class 3 or a mix of Class 2 and 3 and:

the storey to which the concession is to apply is used only for carparking, or an ancillary purpose such as storage of normal household items (see and );
in the case of Class 2 buildings, contain no more than 4 storeys (see ); and
in the case of Class 3 buildings or buildings that are a mix of Class 2 and 3, contain no more than 3 storeys (see ).

The reason for the concession applying to an additional storey in Class 2 buildings is that the residents of these buildings are long term and are usually aware of the building layout and exit routes. This concept is consistent with .

The concession does not apply if the building contains any other classification of building.

2.9

Residential aged care building: Concession

Intent

To allow concessions for the fire protection of certain building elements in Residential aged care buildings when a suitable sprinkler system is used to achieve an adequate level of occupant safety.

“Residential aged care building” is defined in .

This concession is a response to concerns expressed by aged care organisations and health authorities in regards to the impact of certain regulatory requirements on the design and operation of aged care hostels and nursing homes.

The requirements for fire separation of individual sole-occupancy units (including self-closing doors) in aged care hostels was considered to impose unwarranted development costs.

Fire compartmentation and the installation of door closers was considered to be impractical in the daily use of an aged care facility. Self-closing fire doors are too heavy and difficult to operate by frail, elderly people. In a number of cases this resulted in the doors being wedged open, thus negating the fire separation.

The limitation of the Class 1b concessions to buildings having an area of 300 m² or less and 12 occupants or less (see ) meant that those concessions could not be used for many aged care hostels. The concessions in are considered to be reasonable for the larger aged care hostels. In some States or Territories it is not acceptable for a Class 1b building to be used to house elderly people or other people who require special care.

The concession contained in applies to the requirements for floors and loadbearing walls as set out in Table 3, or . of . The concession, allowing a reduction in FRLs, is limited to where the wall is an internal wall. An external wall is not subject to this concession.

The concession contained in . The conditions outlined in must be achieved for the concession to apply. These conditions require walls to be:

lined with 13 mm standard grade plasterboard, or a non-combustible material equivalent to 13 mm standard grade plasterboard (see ); and
extend to the underside of the floor above, a ceiling lined with standard grade plasterboard not less than 13 mm thick or equivalent fire protective material, or a non-combustible roof covering. The wall height requirement aims to create a smoke proof wall. This aim requires that joints and the like be sealed to prevent the spread of smoke through potential cracks and openings (see ).

requires that any insulation in a cavity in a non-loadbearing internal wall must be non-combustible. This is to limit the spread of fire by way of the wall cavity.

The mandatory use of non-combustible materials prohibits the lining of non-loadbearing internal walls with timber panelling. This does not restrict the use of timber mouldings and the like.

In addition to the above concessions for load bearing and non-load bearing walls, doors in a Class 3 building must still comply with the requirements of , and walls must still comply with the requirements of —Sound Transmission and Insulation.

Other provisions relating to Residential aged care buildings are contained throughout the BCA. These include:

C3.11(d)(ii), regarding construction bounding sole-occupancy units and public corridors;
Clause 6(c) of Specification E2.2a, regarding warning systems; and
Specification E1.5, regarding sprinkler systems.

3. Type A Fire-Resisting Construction

3.1

Fire-resistance of building elements

In a building required to be of Type A construction—

(a)

each building element listed in Table 3 and any beam or column incorporated in it, must have an FRL not less than that listed in the Table for the particular Class of building concerned; and

(b)

* * * * *

(c)

any internal wall required to have an FRL with respect to integrity and insulation must extend to—

(i)

the underside of the floor next above; or

(ii)

the underside of a roof complying with Table 3; or

(iii)

if under Clause 3.5 the roof is not required to comply with Table 3, the underside of the non-combustible roof covering and, except for roof battens with dimensions of 75 mm x 50 mm or less or sarking-type material, must not be crossed by timber or other combustible building elements; or

(iv)

a ceiling that is immediately below the roof and has a resistance to the incipient spread of fire to the roof space between the ceiling and the roof of not less than 60 minutes; and

(d)

a loadbearing internal wall and a loadbearing fire wall (including those that are part of a loadbearing shaft) must be constructed from—

(i)

concrete; or

(ii)

masonry; or

(iii)

fire-protected timber, provided that—

(A)

the building is a Class 2, 3 or 5 building which is—

(aa)

a separate building; or

(bb)

a part of a building—

(AA)

which only occupies part of a storey, and is separated from the remaining part by a fire wall; or

(BB)

which is located above or below a part not containing fire-protected timber and the floor between the adjoining parts is provided with an FRL not less than that prescribed for a fire wall for the lower storey; and

(B)

the building has an effective height of not more than 25 m; and

(C)

the building has a sprinkler system throughout complying with Specification E1.5; and

(D)

any insulation installed in the cavity of the timber building element required to have an FRL is non-combustible; and

(E)

cavity barriers are provided in accordance with Specification C1.13; or

(iv)

any combination of (i) to (iii).

(e)

* * * * *

(f)

the FRLs specified in Table 3 for an external column apply also to those parts of an internal column that face and are within 1.5 m of a window and are exposed through that window to a fire-source feature.

Table 3 TYPE A CONSTRUCTION: FRL OF BUILDING ELEMENTS

Building element	Class of building — FRL: (in minutes) Structural adequacy/Integrity/Insulation
2, 3 or 4 part	5, 7a or 9	6	7b or 8
EXTERNAL WALL (including any column and other building element incorporated within it) or other external building element, where the distance from any fire-source feature to which it is exposed is—
For loadbearing parts—
less than 1.5 m	90/ 90/ 90	120/120/120	180/180/180	240/240/240
1.5 to less than 3 m	90/ 60/ 60	120/ 90/ 90	180/180/120	240/240/180
3 m or more	90/ 60/ 30	120/ 60/ 30	180/120/ 90	240/180/ 90
For non-loadbearing parts—
less than 1.5 m	–/ 90/ 90	–/120/120	–/180/180	–/240/240
1.5 to less than 3 m	–/ 60/ 60	–/ 90/ 90	–/180/120	–/240/180
3 m or more	–/–/–	–/–/–	–/–/–	–/–/–
EXTERNAL COLUMN not incorporated in an external wall—
For loadbearing columns—
90/–/–	120/–/–	180/–/–	240/–/–
For non-loadbearing columns—
–/–/–	–/–/–	–/–/–	–/–/–
COMMON WALLS and FIRE WALLS—	90/ 90/ 90	120/120/120	180/180/180	240/240/240
INTERNAL WALLS—
Fire-resisting lift and stair shafts—
Loadbearing	90/ 90/ 90	120/120/120	180/120/120	240/120/120
Non-loadbearing	–/ 90/ 90	–/120/120	–/120/120	–/120/120
Bounding public corridors, public lobbies and the like—
Loadbearing	90/ 90/ 90	120/–/–	180/–/–	240/–/–
Non-loadbearing	–/ 60/ 60	–/–/–	–/–/–	–/–/–
Between or bounding sole-occupancy units—
Loadbearing	90/ 90/ 90	120/–/–	180/–/–	240/–/–
Non-loadbearing	–/ 60/ 60	–/–/–	–/–/–	–/–/–
Ventilating, pipe, garbage, and like shafts not used for the discharge of hot products of combustion—
Loadbearing	90/ 90/ 90	120/ 90/ 90	180/120/120	240/120/120
Non-loadbearing	–/ 90/ 90	–/ 90/ 90	–/120/120	–/120/120

OTHER LOADBEARING INTERNAL WALLS, INTERNAL BEAMS, TRUSSES
and COLUMNS—	90/–/–	120/–/–	180/–/–	240/–/–
FLOORS	90/ 90/ 90	120/120/120	180/180/180	240/240/240
ROOFS	90/ 60/ 30	120/ 60/ 30	180/ 60/ 30	240/ 90/ 60

3.2

Concessions for floors

A floor need not comply with Table 3 if—

(a)

it is laid directly on the ground; or

(b)

in a Class 2, 3, 5 or 9 building, the space below is not a storey, does not accommodate motor vehicles, is not a storage or work area, and is not used for any other ancillary purpose; or

(c)

it is a timber stage floor in a Class 9b building laid over a floor having the required FRL and the space below the stage is not used as a dressing room, store room, or the like; or

(d)

it is within a sole-occupancy unit in a Class 2 or 3 building or Class 4 part of a building; or

(e)

it is an open-access floor (for the accommodation of electrical and electronic services and the like) above a floor with the required FRL.

3.3

Floor loading of Class 5 and 9b buildings: Concession

If a floor in a Class 5 or 9b building is designed for a live load not exceeding 3 kPa—

(a)

the floor next above (including floor beams) may have an FRL of 90/90/90; or

(b)

the roof, if that is next above (including roof beams) may have an FRL of 90/60/30.

3.4

Roof superimposed on concrete slab: Concession

A roof superimposed on a concrete slab roof need not comply with Clause 3.1 as to fire-resisting construction if—

(a)

the superimposed roof and any construction between it and the concrete slab roof are non-combustible throughout; and

(b)

the concrete slab roof complies with Table 3.

3.5

Roof: Concession

A roof need not comply with Table 3 if its covering is non-combustible and the building—

(a)

has a sprinkler system complying with Specification E1.5 installed throughout; or

(b)

has a rise in storeys of 3 or less; or

(c)

is of Class 2 or 3; or

(d)

has an effective height of not more than 25 m and the ceiling immediately below the roof has a resistance to the incipient spread of fire to the roof space of not less than 60 minutes.

3.6

Rooflights

If a roof is required to have an FRL or its covering is required to be non-combustible, rooflights or the like installed in that roof must—

(a)

have an aggregate area of not more than 20% of the roof surface; and

(b)

be not less than 3 m from—

(i)

any boundary of the allotment other than the boundary with a road or public place; and

(ii)

any part of the building which projects above the roof unless that part has the FRL required of a fire wall and any openings in that part of the wall for 6 m vertically above the rooflight or the like are protected in accordance with C3.4; and

(iii)

any rooflight or the like in an adjoining sole-occupancy unit if the walls bounding the unit are required to have an FRL; and

(iv)

any rooflight or the like in an adjoining fire-separated section of the building; and

(c)

if a ceiling with a resistance to the incipient spread of fire is required, be installed in a way that will maintain the level of protection provided by the ceiling to the roof space.

3.7

Internal columns and walls: Concession

For a building with an effective height of not more than 25 m and having a roof without an FRL in accordance with Clause 3.5, in the storey immediately below that roof, internal columns other than those referred to in Clause 3.1(f) and internal walls other than fire walls and shaft walls may have—

(a)

in a Class 2 or 3 building: FRL 60/60/60; or

(b)

in a Class 5, 6, 7, 8 or 9 building—

(i)

with rise in storeys exceeding 3: FRL 60/60/60

(ii)

with rise in storeys not exceeding 3: no FRL.

3.8

Open spectator stands and indoor sports stadiums: Concession

In an open spectator stand or indoor sports stadium, the following building elements need not have the FRL specified in Table 3:

(a)

The roof if it is non-combustible.

(b)

Columns and loadbearing walls supporting only the roof if they are non-combustible.

(c)

Any non-loadbearing part of an external wall less than 3 m—

(i)

from any fire-source feature to which it is exposed if it has an FRL of not less than –/60/60 and is non-combustible; or

(ii)

from an external wall of another open spectator stand if it is non-combustible.

3.9

Carparks

(a)

Notwithstanding Clause 3.1, a carpark may comply with Table 3.9 if it is an open-deck carpark or is protected with a sprinkler system complying with Specification E1.5 and is—

(i)

a separate building; or

(ii)

a part of a building—

(A)

which only occupies part of a storey, and is separated from the remaining part by a fire wall; or

(B)

which is located above or below another classification, and the floor separating the classifications complies with C2.9; or

(C)

which is located above another Class 7 part of the building not used for carparking, and the floor separating the parts complies with Table 3 for a Class 7 part other than a carpark; or

(D)

which is located below another Class 7 part of the building not used for carparking, and the floor separating the parts complies with Table 3.9.

(b)

For the purposes of this Clause, a carpark—

(i)

includes—

(A)

an administration area associated with the functioning of the carpark; and

(B)

where the carpark is sprinklered, is associated with a Class 2 or 3 building and provides carparking for separate sole-occupancy units, each carparking area with an area not greater than 10% of its floor area for purposes ancillary to the sole-occupancy units; but

(ii)

excludes—

(A)

except for (b)(i), any area of another classification, or other part of a Class 7 building not used for carparking; and

(B)

a building or part of a building specifically intended for the parking of trucks, buses, vans and the like.

Table 3.9 REQUIREMENTS FOR CARPARKS

Building element			FRL (not less than) ESA/M (not greater than)
Wall
(a)	external wall
(i)	less than 3 m from a fire-source feature to which it is exposed:
Loadbearing	60/60/60
Non-loadbearing	–/60/60
(ii)	3 m or more from a fire-source feature to which it is exposed	–/–/–
(b)	internal wall
(i)	loadbearing, other than one supporting only the roof (not used for carparking)	60/–/–
(ii)	supporting only the roof (not used for carparking)	–/–/–
(iii)	non-loadbearing	–/–/–
(c)	fire wall
(i)	from the direction used as a carpark	60/60/60
(ii)	from the direction not used as a carpark	as required by Table 3
Column
(a)	supporting only the roof (not used for carparking) and 3 m or more from a fire-source feature to which it is exposed		–/–/–
(b)	steel column, other than one covered by (a) and one that does not support a part of a building that is not used as a carpark		60/–/– or 26 m²/tonne
(c)	any other column not covered by (a) or (b)		60/–/–
Beam
(a)	steel floor beam in continuous contact with a concrete floor slab		60/–/– or 30 m²/tonne
(b)	any other beam		60/–/–
Fire-resisting lift and stair shaft (within the carpark only)			60/60/60
Floor slab and vehicle ramp			60/60/60
Roof (not used for carparking)			–/–/–
Notes: ESA/M means the ratio of exposed surface area to mass per unit length. Refer to Specification E1.5 for special requirements for a sprinkler system in a carpark complying with Table 3.9 and located within a multi-classified building.

3.10

Class 2 and 3 buildings: Concession

(a)

A Class 2 or 3 building having a rise in storeys of not more than 3 need not comply with Clause 3.1 (d) of Specification C1.1 and the requirements of C1.9(a), (b) and C2.6 for non-combustible material, if it is constructed using—

(i)

timber framing throughout; or

(ii)

non-combustible material throughout; or

(iii)

a combination of (i) and (ii),

provided—

(iv)

* * * * *

(v)

any insulation installed in the cavity of a wall required to have an FRL is non-combustible; and

(vi)

the building is fitted with an automatic smoke alarm system complying with Specification E2.2a.

(b)

A Class 2 or 3 building having a rise in storeys of not more than 4 may have the top three storeys constructed in accordance with (a) provided—

(i)

the lowest storey is used solely for the purpose of parking motor vehicles or for some other ancillary purpose; and

(ii)

the lowest storey is constructed of concrete or masonry including the floor between it and the Class 2 or 3 part of the building above; and

(iii)

the lowest storey and the storey above are separated by construction having an FRL of not less than 90/90/90 with no openings or penetrations that would reduce the fire-resisting performance of that construction except that a doorway in that construction may be protected by a –/60/30 self-closing fire door.

(c)

In a Class 2 or 3 building complying with (a) or (b) and fitted with a sprinkler system complying with Specification E1.5, any FRL criterion prescribed in Table 3—

(i)

for any floor and any loadbearing wall, may be reduced to 60, except any FRL criterion of 90 for an external wall must be maintained when tested from the outside; and

(ii)

for any non-loadbearing internal wall, need not apply if—

(A)

it is lined on each side with 13 mm standard grade plasterboard or similar non-combustible material; and

(B)

it extends—

(aa)

to the underside of the floor next above; or

(bb)

to the underside of a ceiling with a resistance to the incipient spread of fire of 60 minutes; or

(cc)

to the underside of a non-combustible roof covering; and

(C)

any insulation installed in the cavity of the wall is non-combustible; and

(D)

any construction joint, space or the like between the top of the wall and the floor, ceiling or roof is smoke sealed with intumescent putty or other suitable material; and

(E)

any doorway in the wall is protected by a self-closing, tight fitting, solid core door not less than 35 mm thick.

3.1

Fire-resistance of building elements

Intent

To specify the fire-resistance level (FRL) and other requirements for building elements in Type A construction.

sets out the required FRLs of building elements in a building required to be of Type A construction. The required FRL depends on whether the element is loadbearing or non-loadbearing, if the element comprises or is incorporated in an external wall, and its distance from any fire-source feature.

When using , it should be noted that permits the deletion of the structural adequacy criteria of an FRL for non-loadbearing elements. The reason for this is that if such an element fails during a fire, there will be no flow-on collapse of other elements. See definition of ‘loadbearing’ in to assist in understanding this provision.

requires building elements to achieve at least the FRLs set out in .

only applies to the building elements listed in , and any beams or columns incorporated in such building elements.

requires internal walls to extend to a barrier to stop or limit the spread of fire over the top of the wall. only applies to internal walls required to have an FRL with respect to integrity and insulation. This is consistent with the intent that the walls are only required to extend to the underside of a floor or roof, etc when the wall is required to perform a fire separating function.

Clause 3.1(d) requires loadbearing internal walls and loadbearing fire walls (in both cases, including those which are part of a loadbearing shaft) to be of concrete, masonry or constructed from fire-protected timber (however, fire-protected timber has certain limitations).

Internal columns can be exposed to a fire-source feature through a window in an external wall. requires such a column within 1.5 metres of a window to have the same FRL as an external column.

3.2

Concessions for floors

Intent

To allow certain floors to not have a fire-resistance level (FRL).

Clause 3.2 grants floors a number of concessions from the FRL requirement. The reason for each of the concessions is listed below:

there is no fire load below a floor laid directly on the ground, (see Clause 3.2(a));
there is a low fire load if the space below a Class 2, 3, 5 or 9 building is not a storey or does not contain the listed elements, (see Clause 3.2(b));
the space below a stage would generally have a low fire load because it cannot be used as a dressing room, storage area, or the like. A fire in the storey below would not affect the stage because it is over a floor with the required FRL. In addition, the stage would not have a room below which might have a high fire load, (see Clause 3.2(c));
the floor is within a residential sole-occupancy unit. This is because resistance to the spread of fire between sole-occupancy units only is required. The levels connected are within the one sole-occupancy unit and the spread of fire from one sole-occupancy unit to another would not be affected by the construction of an internal floor without the required FRL, (see Clause 3.2(d)); and
no fire separation is required for an open-access floor as a fire in the storey below could not affect the area because it is over a floor with the required FRL, (see Clause 3.2(e)).

3.3

Floor loading of Class 5 and 9b buildings: Concession

Intent

To allow a floor or roof in a Class 5 or Class 9b building to have a reduced fire-resistance level (FRL) if it is above a storey with a lower fire load.

Generally, Class 5 and Class 9b buildings have a comparatively low fire load which can be further reduced if the structural carrying capacity of the floor (“live load” or “imposed action”) is restricted because there will be a lower likelihood of the building containing a high level of stored combustible materials. AS 1170.1 and AS/NZS 1170.1 allows certain areas within office (Class 5) and assembly (Class 9b) buildings to have design floor loads of 3 kPa.

In essence, the lower the structural carrying capacity of the storey’s floor, the lower the fire load. This lower fire load in turn permits a reduced FRL for the floor or roof above such a storey.

The philosophy of fire protection in this provision is that the fire load of a storey controls the FRL of the floor or roof above it. This is because a fire on one storey will affect the level above to a greater degree than itself.

Clause 3.3(a) sets out the concession for a floor above, and Clause 3.3(b) sets out the concession for the roof above.

3.4

Roof superimposed on concrete slab: Concession

Intent

To allow a non-combustible non-fire-rated roof to be superimposed on a concrete slab roof.

Clause 3.4allows a concession for a roof of non-fire-resisting construction to be superimposed above a concrete slab roof. Such roofs are usually used for weather protection reasons.

Clause 3.4(a)states that the superimposed roof and any supporting members must be non-combustible.

Clause 3.4(b)states that the concrete slab roof must comply with Table 3 of Specification C1.1.

If compliance is achieved with the conditions outlined in Clause 3.4, a concession is reasonable because a fire is unlikely to break through the concrete roof slab.

3.5

Roof: Concession

Intent

To allow the roofs of certain buildings not to have a fire-resistance level (FRL).

The roofs of certain types of buildings can be required to have an FRL to limit the spread of fire from the roof to another building, or from another building to the roof. Clause 3.5 grants a number of concessions by which certain roofs need not have an FRL, provided the roof covering is non-combustible.

In Clause 3.5(a), the BCA assumes that the specified sprinkler system will control any fire prior to it breaking through the roof.

In Clause 3.5(b), the BCA assumes buildings with a rise in storeys of 3 or less will comprise a comparatively low fire risk. Most buildings with a rise in storeys of 3 or less are permitted to be of Type B or Type C construction.

In Clause 3.5(c), the BCA assumes that Class 2 and Class 3 buildings have a relatively low fire load compared to other classifications, and recognises that the potential size of a fire in Class 2 and Class 3 buildings is limited by the bounding construction of the sole-occupancy units. This concession does not apply where another classification forms part of the storey immediately below the roof (eg a restaurant, which is Class 6).

Clause 3.5(d) assumes that the incipient spread of fire resistant ceiling will stop or limit the spread of fire to the roof space or roof of the building for sufficient time for it to be brought under control.

3.6

Roof lights

Intent

To permit roof lights or the like in a roof that is required to either have an FRL or have a non-combustible covering.

The roofs of certain types of building can be required to have an FRL, or to be of non-combustible construction, to limit the spread of fire from the roof to another building. This is particularly the case with a high rise building. Clause 3.6 specifies the requirements for such roof lights.

The requirements of Clause 3.6 aim to minimise the risk that fire will spread by way of roof lights:

from another building on an adjoining allotment;
to an adjoining sole-occupancy unit; or
to an adjoining fire compartment or fire-separated part of the building.

facilitates this aim by minimising the:

roof area which can be comprised of roof lights (see );
distance a roof light is from an allotment boundary (see );
distance a roof light is from unprotected parts of the building which are higher than the roof (see );
distance a roof light is from roof lights or the like in adjoining sole-occupancy units, if the bounding walls are required to have an FRL (see ); and
distance a roof light is from any roof light or the like in adjoining fire-separated parts of the building (see ).

In some cases, the BCA requires incipient spread of fire resistant ceilings to stop or limit the spread of a fire to the roof space.

provision requires that roof lights be installed in a manner which will maintain the requisite level of protection. This is an example of a “performance-type” provision within the Deemed-to-Satisfy Provisions. This is because a ceiling that has resistance to the incipient spread of fire is tested in the horizontal plane.

If roof lights are installed in a building, it may be necessary to install part of the ceiling in the vertical plane to connect the roof light with the ceiling below. Where this occurs, it may be necessary for a building proponent to provide evidence to an appropriate authority that the method proposed will meet the requirements of .

However, in this case, if the material is installed on a vertical plane yet complies in all other respects with the tested prototype, it is unlikely that the ceiling's fire performance will be affected.

3.7

Internal columns and walls: Concession

Intent

To allow lower fire-resistance levels (FRLs) for internal columns and walls which only support a non-fire-resisting roof.

In the storey immediately below the roof, under circumstances specified in Clause 3.7, it is permissible to reduce or (in some cases) delete the FRL of:

columns, other than those in that are:
- within 1.5 metres of a window;
- face that window; and
- exposed to a fire-source feature through that window; and
internal walls, other than fire walls and shaft walls.

Clause 3.7 does not negate the need for internal columns to have the same FRL as an external column (set out in Clause 3.1(f)) where that internal column is:

within 1.5 metres of a window;
faces that window; and
exposed to a fire-source feature through that window.

3.8

Open spectator stands and indoor sports stadiums: Concession

Intent

To allow lower fire-resistance levels (FRLs) for building elements in open spectator stands and indoor sports stadiums.

The concession is based on the BCA’s overall assumption that there is generally a lower risk to the occupants of open spectator stands and indoor sports stadiums than in other buildings. The reasons for this concession are that:

an open spectator stand generally has a low fire load, even though it may have a high population, particularly during an event, and is open at the front, facilitating the ventilation of smoke and heat; and
in most indoor sports stadiums large areas are usually inaccessible to the public (being taken up as part of the sporting events) and the finishes are generally spartan.

See for definition of “open spectator stand”.

3.9

Carparks

Intent

To allow lower fire-resistance levels (FRLs) for building elements in open-deck or sprinklered carparks.

and Table 3.9 are based on experimental research carried out at the BHP Research Laboratories. The research included full-scale fire tests on open-deck and enclosed carparks, and was supplemented by extensive overseas testing.

The research showed that the Table 3.9 FRLs will not lead to an unsafe situation or structural failure of a building element in an open-deck carpark, or an enclosed carpark, which is sprinkler protected.

See for definition of “carpark”. refines this definition when the expression is used in Clause 3.9 and Table 3.9.

Inclusions

concessions include:

a building which solely comprises a carpark (see );
the carpark section of a building which, in part, has another use, and where the carpark and that use are fire-separated as required in - (regardless of the classification of that use, or whether that use is next to, above or below the carpark) (see );
any administrative area associated with the carpark, such as ticket selling and fee collection areas (see ); and
in a sprinkler protected carpark, small areas ancillary to a Class 2 or Class 3 building, such as part of the carpark used for normal ‘household’ storage (see ).

Exclusions

concessions exclude:

any area of another Class (see );
another Class 7 use (i.e. other than carparking), (see ); and
an area “specifically intended” for the parking of vehicles such as trucks, buses, vans and the like (see ).

and , while using a refined definition of “carpark”, also use the undefined expression “carparking”. This word specifically refers to the parking of cars. This is also the intention of refining the definition of “carpark” as expressed by the use of the words “specifically intended” in .

The purpose of refining this definition, which is to limit the concessions in to areas used for the parking of lighter vehicles (that is, vehicles other than commercial trucks, vans, buses and the like), rather than simply limiting them to areas used for the parking of cars only.

Accordingly, it would seem contrary to the purpose of this clause to exclude from the refined definition and the word “carparking” such vehicles as motor bikes, van-like family vehicles, non-commercial panel vans, and smaller non-commercial utilities.

permits building elements to have either a specified FRL or a specified surface area to mass ratio. In relation to columns and beams, does not require them to have an FRL if they have the specified surface area to mass ratio. Some authorities refer to this ratio as the “heat sink effect”, in that the lower the exposed surface area to mass ratio, the lower will be the member temperature for a given fire.

The concession of relating to columns, only applies to columns of any material which support a roof which is not used for carparking, and located 3 metres or more from a fire-source feature to which they are exposed.

The concession of only applies to steel columns which support a roof which is used for carparking, and/or located less than 3 metres from a fire-source feature to which they are exposed. This concession is not applicable if the steel columns support any other part of the building which is not used as a carpark.

Columns of any material that do not qualify for and concessions are subject to .

Example

The concession of (b) in the columns section of does not apply if the column supports a part of the building specifically intended for the parking of trucks, buses, vans, and the like.

In the section of relating to roofs, there is a concession for roofs that are not used for carparking.

A roof used for carparking must comply with any relevant requirements of (eg those relating to floor slabs).

3.10

Class 2 and 3 buildings: Concession

Intent

To allow low-rise Class 2 and 3 buildings which are required to be of Type A construction to be constructed with timber framing and/or non-combustible materials.

results from research undertaken by the National Association of Forest Industries and Forest and Wood Products Australia, which have been confirmed by overseas studies.

provides a concession to and also to the combustibility requirements of C1.9(a) and (b) and C2.6 to allow, subject to specified conditions, the use, in certain Class 2 and 3 buildings, timber framing instead of an alternative structural support system using non-combustible materials, concrete, or masonry.

allows the use of timber framing.

allows the use of non-combustible materials (such as steel) for firewalls and internal walls required to be fire resisting, instead of concrete or masonry as required by .

allows a combination of timber framing and non-combustible materials.

The concession to use timber framing and/or non-combustible materials is conditional on:

a firewall or internal wall required to be fire-resisting being extended to the underside of the non-combustible roof covering. The wall height requirement, together with the smoke sealing requirement of , aims to create a smoke proof wall, hence the requirement for sealing any cracks and openings against the spread of smoke, (see ) It should be noted that these walls may need to meet other requirements of Type A construction such as those of ;
only non-combustible insulation being used in a wall cavity. This aims to limit the spread of fire by way of the cavity; and
an automatic smoke alarm system being installed in the building to give early warning of a fire.

allows the top three storeys of a four storey Class 2 or 3 building to be constructed with timber framing and/or non-combustible materials if they are located above a single storey used for vehicle parking (note that the limitation in by use of the word “carparking” does not apply here) and ancillary purposes. These ancillary purposes include such items as individual storerooms, laundries, and the like.

To achieve this concession, the lowest carparking storey (including the floor/ceiling between the carpark and the storey above) must be constructed of concrete or masonry, and have the FRLs specified in , or reduced by . The floor between the carpark and the storey above must not contain penetrations or openings that would reduce the fire-resisting performance of the floor. The exception to this is a door which is permitted to be a –/60/30 self-closing fire door.

Under the Clause 2.8 concession, the vehicle parking storey can be classified as a Class 2 or 3 building for the purpose of determining the relevant fire-resisting requirements of .

The basis of the concession is that the concrete or masonry floor of the first storey above the lowest carparking storey will provide adequate fire separation. does not require smoke detectors or sprinklers in the lowest carparking storey because a fire occurring in it should not pose an unacceptable risk to occupants evacuating from the upper three storeys.

Compliance must still be achieved with the other requirements of and other parts of the BCA, including the relevant FRLs listed in , and any relevant requirements of Clause E1.5.

Subject to the conditions listed, including the installation of a sprinkler system, allows:

a reduction of the FRL of loadbearing walls (see ); and
the deletion of the FRL for non-loadbearing internal walls (see ).

Reference to Clause 2 of Specification E1.5 indicates that the required sprinkler system need only comply with AS 2118.4—Automatic fire sprinkler systems—Residential. This Standard has been specifically developed to provide a degree of life safety and property protection for occupants of low-rise Class 2 and 3 buildings. If the storey used as carpark requires sprinklers by , then the carpark is considered a Class 7 building for the purposes of applying (see ).

allows non-loadbearing internal walls to have no FRL. The concession is subject to the requirement that the internal walls be lined on each side with 13 mm standard grade plasterboard or non-combustible materials with a similar fire-resisting performance. This means that all doors from sole-occupancy units to corridors, when applying these concessions, must be smoke proof doors. Self-closing solid core doors satisfy this requirement (see ).

The provision regarding the height of a non-loadbearing wall, to which this concession is applied, aims to create a smoke proof wall, hence the requirement for sealing any cracks and openings against the spread of smoke.

The requirement that only non-combustible insulation can be used in a cavity in a non-loadbearing wall, to which this concession is applied, aims to limit the spread of fire by way of the cavity.

4. Type B Fire-Resisting Construction

4.1

Fire-resistance of building elements

In a building required to be of Type B construction—

(a)

each building element listed in Table 4, and any beam or column incorporated in it, must have an FRL not less than that listed in the Table for the particular Class of building concerned; and

(b)

* * * * *

(c)

if a stair shaft supports any floor or a structural part of it—

(i)

the floor or part must have an FRL of 60/–/– or more; or

(ii)

the junction of the stair shaft must be constructed so that the floor or part will be free to sag or fall in a fire without causing structural damage to the shaft; and

(d)

any internal wall which is required to have an FRL with respect to integrity and insulation, except a wall that bounds a sole-occupancy unit in the topmost (or only) storey and there is only one unit in that storey, must extend to—

(i)

the underside of the floor next above if that floor has an FRL of at least 30/30/30; or

(ii)

the underside of a ceiling having a resistance to the incipient spread of fire to the space above itself of not less than 60 minutes; or

(iii)

the underside of the roof covering if it is non-combustible and, except for roof battens with dimensions of 75 mm x 50 mm or less or sarking-type material, must not be crossed by timber or other combustible building elements; or

(iv)

450 mm above the roof covering if it is combustible; and

(e)

a loadbearing internal wall and a loadbearing fire wall (including those that are part of a loadbearing shaft) must be constructed from—

(i)

concrete; or

(ii)

masonry; or

(iii)

fire-protected timber, provided that—

(A)

the building is a Class 2, 3 or 5 building which is—

(aa)

a separate building; or

(bb)

a part of a building—

(AA)

which only occupies part of a storey, and is separated from the remaining part by a fire wall; or

(BB)

(B)

the building has an effective height of not more than 25 m; and

(C)

the building has a sprinkler system throughout complying with Specification E1.5; and

(D)

any insulation installed in the cavity of the timber building element required to have an FRL is non-combustible; and

(E)

cavity barriers are provided in accordance with Specification C1.13; or

(iv)

any combination of (i) to (iii).

(f)

* * * * *

(g)

in a Class 5, 6, 7, 8 or 9 building, in the storey immediately below the roof, internal columns and internal walls other than fire walls and shaft walls, need not comply with Table 4; and

(h)

* * * * *

(i)

in a Class 2 or 3 building, except where within the one sole-occupancy unit, or a Class 9a health-care building or a Class 9b building, a floor separating storeys or above a space for the accommodation of motor vehicles or used for storage or any other ancillary purpose, must—

(i)

be constructed so that it is at least of the standard achieved by 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

(ii)

have an FRL of at least 30/30/30; or

(iii)

have a fire-protective covering on the underside of the floor, including beams incorporated in it, if the floor is combustible or of metal; and

(j)

in a Class 9c building a floor above a space for the accommodation of motor vehicles or used for storage or any other ancillary purpose, and any column supporting the floor must—

(i)

(ii)

have an FRL of at least 30/30/30; or

(iii)

have a fire-protective covering on the underside of the floor, including beams incorporated in it, if the floor is combustible or of metal.

Table 4 TYPE B CONSTRUCTION: FRL OF BUILDING ELEMENTS

Building element	Class of building — FRL: (in minutes) Structural adequacy/Integrity/Insulation
2, 3 or 4 part	5, 7a or 9	6	7b or 8
EXTERNAL WALL (including any column and other building element incorporated within it) or other external building element, where the distance from any fire-source feature to which it is exposed is—
For loadbearing parts—
less than 1.5 m	90/ 90/ 90	120/120/120	180/180/180	240/240/240
1.5 to less than 3 m	90/ 60/ 30	120/ 90/ 60	180/120/ 90	240/180/120
3 to less than 9 m	90/ 30/ 30	120/ 30/ 30	180/ 90/ 60	240/ 90/ 60
9 to less than 18 m	90/ 30/–	120/ 30/–	180/ 60/–	240/ 60/–
18 m or more	–/–/–	–/–/–	–/–/–	–/–/–
For non-loadbearing parts—
less than 1.5 m	–/ 90/ 90	–/120/120	–/180/180	–/240/240
1.5 to less than 3 m	–/ 60/ 30	–/ 90/ 60	–/120/ 90	–/180/120
3 m or more	–/–/–	–/–/–	–/–/–	–/–/–
EXTERNAL COLUMN not incorporated in an external wall, where the distance from any fire-source feature to which it is exposed is—
For loadbearing columns—
less than 18 m	90/–/–	120/–/–	180/–/–	240/–/–
18 m or more	–/–/–	–/–/–	–/–/–	–/–/–
For non-loadbearing columns—
–/–/–	–/–/–	–/–/–	–/–/–
COMMON WALLS and FIRE WALLS—	90/ 90/ 90	120/120/120	180/180/180	240/240/240
INTERNAL WALLS—
Fire-resisting lift and stair shafts—
Loadbearing	90/ 90/ 90	120/120/120	180/120/120	240/120/120
Fire-resisting stair shafts—
Non-loadbearing	–/ 90/ 90	–/120/120	–/120/120	–/120/120
Bounding public corridors, public lobbies and the like—
Loadbearing	60/ 60/ 60	120/–/–	180/–/–	240/–/–
Non-loadbearing	–/ 60/ 60	–/–/–	–/–/–	–/–/–
Between or bounding sole-occupancy units—
Loadbearing	60/ 60/ 60	120/–/–	180/–/–	240/–/–
Non-loadbearing	–/ 60/ 60	–/–/–	–/–/–	–/–/–
OTHER LOADBEARING INTERNAL WALLS
and COLUMNS—	60/–/–	120/–/–	180/–/–	240/–/–
ROOFS	–/–/–	–/–/–	–/–/–	–/–/–

4.2

Carparks

(a)

Notwithstanding Clause 4.1, a carpark may comply with Table 4.2 if it is an open-deck carpark or is protected with a sprinkler system complying with Specification E1.5 and is—

(i)

a separate building; or

(ii)

a part of a building, and if occupying only part of a storey, is separated from the remaining part by a fire wall.

(b)

For the purposes of this Clause, a carpark—

(i)

includes—

(A)

an administration area associated with the functioning of the carpark; and

(B)

(ii)

excludes—

(A)

except for (b)(i), any area of another classification, or other part of a Class 7 building not used for carparking; and

(B)

a building or part of a building specifically intended for the parking of trucks, buses, vans and the like.

Table 4.2 REQUIREMENTS FOR CARPARKS

Building element			FRL (not less than) Structural adequacy/Integrity/ Insulation ESA/M (not greater than)
Wall
(a)	external wall
(i)	less than 3 m from a fire-source feature to which it is exposed:
Loadbearing	60/60/60
Non-loadbearing	–/60/60
(ii)	3 m or more from a fire-source feature to which it is exposed	–/–/–
(b)	internal wall
(i)	loadbearing, other than one supporting only the roof (not used for carparking)	60/–/–
(ii)	supporting only the roof (not used for carparking)	–/–/–
(iii)	non-loadbearing	–/–/–
(c)	fire wall
(i)	from the direction used as a carpark	60/60/60
(ii)	from the direction not used as a carpark	as required by Table 4
Column
(a)	supporting only the roof (not used for carparking) and 3 m or more from a fire-source feature to which it is exposed		–/–/–
(b)	steel column, other than one covered by (a)		60/–/– or 26 m²/tonne
(c)	any other column not covered by (a) or (b)		60/–/–
Beam
(a)	less than 3 m from a fire-source feature:
(i)	steel floor beam in continuous contact with a concrete floor slab	60/–/– or 30 m²/tonne
(ii)	any other beam	60/–/–
(b)	3 m or more from a fire-source feature		60/–/– or 30 m²/tonne
Lift shaft			–/–/–
Fire-resisting stair shaft (within the carpark only)			60/60/60
Roof, floor slab and vehicle ramp			–/–/–
Notes: ESA/M means the ratio of exposed surface area to mass per unit length.

4.3

Class 2 and 3 buildings: Concession

(a)

A Class 2 or 3 building having a rise in storeys of not more than 2 need not comply with Clause 4.1(e)of) of Specification C1.1 and the requirements of C1.9(a) and (b) for non-combustible materials, if it is constructed using—

(i)

timber framing throughout; or

(ii)

non-combustible material throughout; or

(iii)

a combination of (i) and (ii),

provided—

(iv)

* * * * *

(v)

any insulation installed in the cavity of a wall required to have an FRL is non-combustible; and

(vi)

the building is fitted with an automatic smoke alarm system complying with Specification E2.2a.

(b)

A Class 2 or 3 building having a rise in storeys of not more than 2 may have the top storey constructed in accordance with (a) provided—

(i)

the lowest storey is used solely for the purpose of parking motor vehicles or for some other ancillary purpose; and

(ii)

the lowest storey is constructed of concrete or masonry including the floor between it and the Class 2 or 3 part of the building above; and

(iii)

(c)

In a Class 2 or 3 building complying with (a) or (b) and fitted with a sprinkler system complying with Specification E1.5, any FRL criterion prescribed in Table 4—

(i)

for any loadbearing wall, may be reduced to 60, except any FRL criterion of 90 for an external wall must be maintained when tested from the outside; and

(ii)

for any non-loadbearing internal wall, need not apply, if—

(A)

it is lined on both sides with 13 mm standard grade plasterboard or similar non-combustible material; and

(B)

it extends—

(aa)

to the underside of the floor next above if that floor has an FRL of at least 30/30/30 or is lined on the underside with a fire-protective covering; or

(bb)

to the underside of a ceiling with a resistance to the incipient spread of fire of 60 minutes; or

(cc)

to the underside of a non-combustible roof covering; and

(C)

any insulation installed in the cavity of the wall is non-combustible; and

(D)

any construction joints, spaces and the like between the top of the wall and the floor, ceiling or roof is smoke sealed with intumescent putty or other suitable material.

4.1

Fire-resistance of building elements

Intent

To specify the fire-resistance level (FRL) and other requirements of building elements in Type B construction.

Table 4 of Specification C1.1 sets out the required FRLs of building elements in a building required to be of Type B construction. The required FRL depends on whether the element is loadbearing or non-loadbearing, if the element comprises or is incorporated in an external wall, and its distance from any fire-source feature to which it is exposed.

Although a roof is an external building element that can be exposed to a fire-source feature, it is not required to comply with the FRLs specified under the heading of external wall in Table 4. The FRLs required for a roof are contained under the heading of roofs near the bottom of the Table.

When using Table 4 of Specification C1.1, it should be noted that Clause 6 of Specification A2.3 permits the deletion of the structural adequacy criterion of an FRL for non-loadbearing elements. The reason for this is that if such an element fails during a fire, there will be no flow-on collapse of other elements. See A1.1 for the definition of “loadbearing”.

Generally speaking, Type B construction differs from Type A construction by allowing lower FRLs for external walls, generally not requiring roofs and floors to have an FRL, and not requiring FRLs for ventilation, garbage, and similar shafts.

These differences are based on the lower rise in storeys allowed by Table C1.1; and the smaller size of Type B construction buildings allowed by Table C2.2.

The BCA requires the floors of buildings required to be of Type B construction to have an FRL in Class 2 and Class 3 buildings, if the floor supports different sole-occupancy units (see Clause 4.1(i)), in Class 9a buildings as part of the fire compartments required by C2.5(a)(iv) and in Class 9c buildings as part of the fire compartments required by C2.5(b)(ii) (see Clause 4.1(j)).

Clause 4.1(a) requires building elements to achieve at least the FRLs set out for them in Table 4. Clause 4.1(a) only applies to the building elements listed in Table 4, and any beams or columns incorporated in such building elements.

Clause 4.1(c) requires stair shafts which support floors or structural parts of floors to either have a specified FRL, or be constructed at the junction of the shaft and floor (or part of floor), so that if the floor falls or collapses (fully or partly) during a fire, the shaft will not be damaged.

Clause 4.1(d) requires internal walls to extend to a barrier to stop or limit the spread of fire over the top of the wall. Such a requirement is not considered necessary when a sole-occupancy unit occupies the whole of the top storey. This concession applies to buildings of Type B construction. Clause 4.1(d) only applies to internal walls required to have an FRL with respect to integrity and insulation. This is consistent with the intent that the walls are only required to extend to the underside of a floor or roof, etc when the wall is required to perform a fire separating function.

Clause 4.1(e) requires loadbearing internal walls and loadbearing fire walls (in both cases, including those which are part of a loadbearing shaft) to be of concrete, masonry or constructed from fire-protected timber (however, fire-protected timber has certain limitations).

Under Clause 4.1(g), internal columns and internal walls need not comply with Table 4 if they are:

in a Class 5–9 building;
in the storey immediately below the roof; and
not fire walls or shaft walls.

Clause 4.1(i) does not apply if the storeys being separated are within a sole-occupancy unit of a Class 2 or 3 building, because it is likely that the two levels are connected by a non-fire-isolated stairway.

The primary reason for the Clause 4.1(i) fire separation requirement is that in a building fire, the highest degree of risk is attached to such people as the very young, people with disabilities, the elderly, and those who are asleep.

Table 5 requires internal walls bounding a stair required to be rated to have an FRL of 60/60/60. The reason for this is because although Table C1.1 only allows buildings of Type C construction to have a maximum rise is storeys of 2, such buildings may include a basement which is not included in the calculation of rise in storeys. If a stairway in the building connects say a basement with two other storeys, in accordance with D1.3, a fire-isolated exit would be required. Table 5 then sets out the required FRL for the walls of the stairway.

Examples

Buildings, which must comply with Clause 4.1(i), include:

A Class 2 building (which includes flats, apartments, etc).
A Class 3 building (which includes hotels, motels, etc).
The residential part of a school.
Accommodation for the aged, children or people with disabilities.
A residential aged care building.
A Class 9a building (which includes hospitals, etc).
A Class 9b building, such as schools, theatres, and the like.

4.2

Carparks

Intent

To allow lower fire-resistance levels (FRLs) for building elements in open-deck or sprinklered carparks.

Clause 4.2 and Table 4.2 are based on experimental research carried out at the BHP Research Laboratories. The research included full scale fire tests on both open-deck and enclosed carparks, and was supplemented by extensive overseas testing.

The research carried out on this matter showed that the Table 4.2 FRLs will not lead to an unsafe situation or structural failure of a building element in an open-deck carpark, or an enclosed carpark which is sprinkler protected.

See A1.1 for definition of “carpark”. Clause 4.2(b) refines this definition when the expression is used in Clause 4.2 and Table 4.2.

Inclusions and exclusions

Clause 4.2 concessions include:

a building which solely comprises a carpark;
the carpark section of a building which elsewhere has another use;
any administrative area associated with the carpark, such as ticket selling and fee collection areas; and
in a sprinkler protected carpark, small areas ancillary to a Class 2 or Class 3 building, such as part of the carpark used for normal “household” storage.

Clause 4.2 concessions exclude:

any area of another Class;
another Class 7 use (i.e. other than carparking); and
an area “specifically intended” for the parking of vehicles such as trucks, buses, vans and the like.

Clause 4.2 and Table 4.2, while using a refined definition of “carpark”, also use the undefined expression “carparking”. This word specifically refers to the parking of cars. This is also the intention of refining the definition of “carpark” as expressed by the use of the words “specifically intended” in Clause 4.2(b)(ii)(B).

However, in applying these provisions, it is important to consider the purpose of refining this definition, which is to limit the concessions in Table 4.2 to areas used for the parking of lighter vehicles (that is, vehicles other than commercial trucks, vans, buses and the like)—rather than simply limiting them to areas used for the parking of cars only.

Regarding certain types of column and beam, Table 4.2 permits them to have either a specified FRL or a specified surface area to mass ratio. In other words, in relation to these columns and beams, Table 4.2 does not require them to have an FRL if they have the specified surface area to mass ratio. Some authorities refer to this ratio as the “heat sink effect”, in that the lower the exposed surface area to mass ratio, the lower will be the member temperature for a given fire.

The concession for columns in Table 4.2(a) applies to columns of any material which support a roof which is not used for carparking, and located 3 metres or more from a fire-source feature to which they are exposed.

The concession in Table 4.2(b) only applies to steel columns that support a roof which is used for carparking, and/or located less than 3 metres from a fire-source feature to which they are exposed. This concession is also applicable where steel columns support any other part of the building that is not used as a carpark.

Columns of any material which do not qualify for the Table 4.2(a) and (b) concessions are subject to Table 4.2(c) .

For the purposes of this clause, the usual definition of “carpark” is specifically amended (see Clause 4.2(b)).

Example

The concession of (b) in the columns section of Table 4.2 does not apply if the column supports a part of the building specifically intended for the parking of trucks, buses, vans, and the like.

Table 3.9 provisions restricting the roof concession to those roofs that are not used for carparking does not apply to Table 4.2.

The differences between Table 4.2 and Table 3.9 are based on the lower rise in storeys allowed for Type B construction buildings by Table C1.1.

4.3

Class 2 and 3 buildings: Concession

Intent

To allow low-rise Class 2 and 3 buildings which are required to be of Type B construction to be constructed with timber framing and/or non-combustible materials.

Clause 4.3 results from research undertaken by the National Association of Forest Industries and Forest and Wood Products Australia, which have been confirmed by overseas studies.

The effect of Clause 4.3 is to provide a concession to Clause 4.1 to allow, subject to specified conditions, the use in certain Class 2 and 3 buildings of timber framing instead of an alternative structural support system using non-combustible materials, or concrete, or masonry.

Clause 4.3(a)(i) allows the use of timber framing.

Clause 4.3(a)(ii) allows the use of non-combustible materials (such as steel) for fire walls and internal walls required to be fire-resisting, instead of concrete or masonry as required by Clause 4.1(e).

Clause 4.3(a)(iii) allows a combination of timber framing and non-combustible materials.

Table C1.1 limits Class 2 and 3 buildings of Type B construction to a rise in storeys of two. For this reason Clause 4.3 only applies to two storey Class 2 and 3 buildings, and no concession is allowed for a two storey timber framed building above a concrete or masonry lower storey, as is allowed in the case of Type A construction buildings by Clause 3.10.

The Clause 4.3(a) concession to use timber framing and/or non-combustible materials is conditional on:

a fire wall or internal wall required to be fire-resisting being extended to the underside of the non-combustible roof covering. The wall height requirement, together with the smoke sealing requirement of Clause 4.3(c)(ii)(D), aims to create a smoke proof wall, hence the requirement for sealing any cracks and openings against the spread of smoke;
only non-combustible insulation being used in a wall cavity. This aims to limit the spread of fire by way of the cavity; and
an automatic smoke alarm system being installed in the building to give early warning of a fire.

Clause 4.3(b) allows a 2 storey Class 2 or 3 building to be constructed with timber framing and/or non-combustible materials if the lowest storey is used for vehicle parking (note that the limitation in Clause 4.2 by use of the word “carparking” does not apply here) and ancillary purposes. These ancillary purposes include such items as individual storerooms, laundries, and the like.

To achieve this concession, the lowest carparking storey (including the floor/ceiling between the carpark and the storey above) must be constructed of concrete or masonry, and have the FRLs specified in Table 4. The floor between the carpark and the storey above must not contain penetrations or openings that would reduce the fire-resisting performance of the floor. The exception to this is a doorway which is permitted to be protected by a –/60/30 self-closing fire door.

Under the Clause 2.8 concession, the carparking storey can be classified as a Class 2 or 3 building for the purpose of determining the relevant fire-resisting requirements of Specification C1.1.

Subject to the conditions listed, including the installation of a sprinkler system, Clause 4.3(c) allows a reduction of the FRL of loadbearing elements, and the deletion of the FRL for non-loadbearing elements.

Reference to Clause 2 of Specification E1.5indicates that the required sprinkler system need only comply with AS 2118.4—Automatic fire sprinkler systems—Residential. This Standard has been specifically developed to provide a degree of life safety and property protection for occupants of low-rise Class 2 or 3 buildings (see E1.5).

Clause 4.3(c)(ii)(A) allows non-loadbearing internal walls to not have an FRL. The concession is subject to the requirement that the internal walls be lined on each side with 13 mm standard grade plasterboard or non-combustible materials.

The Clause 4.3(c)(ii)(B) provision regarding the height of a non-loadbearing wall to which this concession is applied aims to create a smoke proof wall, hence the Clause 4.3(c)(ii)(D) requirement for sealing any cracks and openings against the spread of smoke.

The Clause 4.3(c)(ii)(C) requirement that only non-combustible insulation can be used in a cavity in a non-loadbearing wall to which this concession is applied aims to limit the spread of fire by way of the cavity.

There is no specific concession to permit the use of solid core doors in Type B construction buildings, unlike that in Clause 3.10(c)(ii)(E), this is because they are already permitted in Type B construction (see C3.11).

The result of Clause 4.3 is that a designer proposing to use the BCA Deemed-to-Satisfy Provisions to design a two storey Class 2 or 3 building of Type B construction has three basic options:

design in accordance with other provisions applicable to buildings of Type B construction which, under C1.9(a) and (b) and Clause 4.1(e), would exclude the use of timber external walls, common walls, loadbearing internal walls, fire walls and non-loadbearing internal walls required to be fire-resisting;
use timber and/or non-combustible materials in accordance with Clause 4.3; or
comply with C1.5 and design for Type C construction, which places no limitations on the use of timber.

5. Type C Fire-Resisting Construction

5.1

Fire-resistance of building elements

In a building required to be of Type C construction—

(a)

a building element listed in Table 5 and any beam or column incorporated in it, must have an FRL not less than that listed in the Table for the particular Class of building concerned; and

(b)

an external wall that is required by Table 5 to have an FRL need only be tested from the outside to satisfy the requirement; and

(c)

a fire wall or an internal wall bounding a sole-occupancy unit or separating adjoining units must comply with Specification C1.8 if it is of lightweight construction and is required to have an FRL; and

(d)

in a Class 2 or 3 building, an internal wall which is required by Table 5 to have an FRL must extend—

(i)

to the underside of the floor next above if that floor has an FRL of at least 30/30/30 or a fire-protective covering on the underside of the floor; or

(ii)

to the underside of a ceiling having a resistance to the incipient spread of fire to the space above itself of not less than 60 minutes; or

(iii)

to the underside of the roof covering if it is non-combustible, and except for roof battens with dimensions of 75 mm x 50 mm or less or sarking-type material, must not be crossed by timber or other combustible building elements; or

(iv)

450 mm above the roof covering if it is combustible; and

(e)

in a Class 2 or 3 building, except where within the one sole-occupancy unit, or a Class 9a health-care building, or a Class 9b building, a floor separating storeys, or above a space for the accommodation of motor vehicles or used for storage or any other ancillary purpose, and any column supporting the floor, must—

(i)

have an FRL of at least 30/30/30; or

(ii)

have a fire-protective covering on the underside of the floor including beams incorporated in it and around the column, if the floor or column is combustible or of metal; and

(f)

in a Class 9c building a floor above a space for the accommodation of motor vehicles or used for storage or any other ancillary purpose, and any column supporting the floor, must—

(i)

have an FRL of at least 30/30/30; or

(ii)

have a fire-protective covering on the underside of the floor including beams incorporated in it and around the column, if the floor or column is combustible or of metal.

Table 5 TYPE C CONSTRUCTION: FRL OF BUILDING ELEMENTS

Building element	Class of building — FRL: (in minutes) Structural adequacy/Integrity/Insulation
2, 3 or 4 part	5, 7a or 9	6	7b or 8
EXTERNAL WALL (including any column and other building element incorporated within it) or other external building element, where the distance from any fire-source feature to which it is exposed is—
less than 1.5 m	90/ 90/ 90	90/ 90/ 90	90/ 90/ 90	90/ 90/ 90
1.5 to less than 3 m	–/–/–	60/ 60/ 60	60/ 60/ 60	60/ 60/ 60
3 m or more	–/–/–	–/–/–	–/–/–	–/–/–
EXTERNAL COLUMN not incorporated in an external wall, where the distance from any fire-source feature to which it is exposed is—
less than 1.5 m	90/–/–	90/–/–	90/–/–	90/–/–
1.5 to less than 3 m	–/–/–	60/–/–	60/–/–	60/–/–
3 m or more	–/–/–	–/–/–	–/–/–	–/–/–
COMMON WALLS and FIRE WALLS—	90/ 90/ 90	90/ 90/ 90	90/ 90/ 90	90/ 90/ 90
INTERNAL WALLS—
Bounding public corridors, public lobbies and the like—	60/ 60/ 60	–/–/–	–/–/–	–/–/–
Between or bounding sole-occupancy units—	60/ 60/ 60	–/–/–	–/–/–	–/–/–
Bounding a stair if required to be rated—	60/ 60/ 60	60/ 60/ 60	60/ 60/ 60	60/ 60/ 60
ROOFS	–/–/–	–/–/–	–/–/–	–/–/–

5.2

Carparks

(a)

Notwithstanding Clause 5.1, a carpark may comply with Table 5.2 if it is an open-deck carpark or is protected with a sprinkler system complying with Specification E1.5 and is—

(i)

a separate building; or

(ii)

a part of a building, and if occupying only part of a storey, is separated from the remaining part by a fire wall.

(b)

For the purposes of this Clause, a carpark—

(i)

includes—

(A)

an administration area associated with the functioning of the carpark; and

(B)

(ii)

excludes—

(A)

except for (b)(i), any area of another classification, or other part of a Class 7 building not used for carparking; and

(B)

a building or part of a building specifically intended for the parking of trucks, buses, vans and the like.

Table 5.2 REQUIREMENTS FOR CARPARKS

Building element			FRL (not less than) Structural adequacy/Integrity/ Insulation ESA/M (not greater than)
Wall
(a)	external wall
(i)	less than 1.5 m from a fire-source feature to which it is exposed:
Loadbearing	60/60/60
Non-loadbearing	–/60/60
(ii)	1.5 m or more from a fire-source feature to which it is exposed	–/–/–
(b)	internal wall		–/–/–
(c)	fire wall
(i)	from the direction used as a carpark	60/60/60
(ii)	from the direction not used as a carpark	90/90/90
Column
(a)	steel column less than 1.5 m from a fire-source feature		60/–/– or 26 m²/tonne
(b)	any other column less than 1.5 m from a fire-source feature		60/–/–
(c)	any other column not covered by (a) or (b)		–/–/–
Beam
(a)	less than 1.5 m from a fire-source feature
(i)	steel floor beam in continuous contact with a concrete floor slab	60/–/– or 30 m²/tonne
(ii)	any other beam	60/–/–
(b)	1.5 m or more from a fire-source feature		–/–/–
Roof, floor slab and vehicle ramp			–/–/–
Notes: ESA/M means the ratio of exposed surface area to mass per unit length.

5.1

Fire-resistance of building elements

Intent

To specify the fire-resistance level (FRL) and other requirements of building elements in a building required to be of Type C construction.

sets out the required FRLs of building elements in a building required to be of Type C construction. If the element comprises or is incorporated in an external wall, the required FRL depends on distance from any fire-source feature to which it is exposed.

Although a roof is an external building element that can be exposed to a fire-source feature, it is not required to comply with the FRLs specified under the heading of external wall in . The FRLs required for a roof are contained under the heading of roofs near the bottom of the table.

Generally speaking, Type C construction differs from Type B construction by allowing lower FRLs for external walls which are located more than 1.5 metres from a fire-source feature, and only requiring a maximum FRL of 90 minutes for any criterion. bases these differences on the lower rise in storeys allowed by , and the smaller size of Type C buildings allowed.

No building element in a building required to be of Type C construction is required to be non-combustible, or of concrete or masonry.

requires building elements to achieve at least the FRLs set out for them in . only applies to the building elements listed in , and any beams or columns incorporated in such building elements.

Where requires an external wall to have an FRL, requires that the wall only need be tested from outside to meet the FRL criteria. This allows the use of brick veneer construction where the brick has the required FRL.

Where a fire wall and the specified internal walls are of lightweight construction they must comply with .

requires internal walls to extend to a barrier to stop or limit the spread of fire over the top of the wall.

The concession contained in for Type B construction with respect to the height of the wall when a sole-occupancy unit occupies the whole of the top storey, does not apply to Type C construction.

To protect building occupants of Class 2, 3 and 9 buildings from fire spread between storeys, establishes the minimum fire separation between storeys in such buildings. This requirement takes into account the special risks that can exist in such buildings.

This requirement also relates to the fire separation of Class 2, 3 and 9 buildings from a carpark or storage area.

does not apply if the storeys being separated are within a sole-occupancy unit of a Class 2 or Class 3 building, because it is likely that the two levels are connected by a non-fire-isolated stairway and would therefore not be required to be fire separated.

The primary reason for the and fire separation requirement is that in a building fire, the highest degree of risk is attached to such people as the very young, people with disabilities, the elderly, and those who are asleep.

Examples

Buildings that must comply with include:

A Class 2 building (which includes flats, apartments, etc).
A Class 3 building (which includes hotels, motels, etc).
The residential part of a school.
Accommodation for the aged, children or people with disabilities.
A residential aged care building.
A Class 9a building (which includes hospitals, etc).
A Class 9b building, such as schools, theatres, and the like.

5.2

Carparks

Intent

To allow lower fire-resistance levels (FRLs) for building elements in open-deck or sprinklered carparks.

and are based on experimental research carried out at the BHP Research Laboratories. The research included full scale fire tests on both open-deck and enclosed carparks, and was supplemented by extensive overseas testing.

The research carried out on this matter showed that the FRLs will not lead to an unsafe situation or structural failure of a building element in an open-deck carpark, or an enclosed carpark which is sprinkler protected.

See for definition of “carpark”. refines this definition when the expression is used in and .

Inclusions and exclusions

The concessions include:

a building which solely comprises a carpark;
the carpark section of a building which elsewhere has another use;
any administrative area associated with the carpark, such as ticket selling and fee collection areas; and
in a sprinkler protected carpark, small areas ancillary to a Class 2 or Class 3 building, such as part of the carpark used for normal ‘household’ storage.

The concessions exclude:

any area of another Class;
another Class 7 use (i.e. other than carparking); and
an area “specifically intended” for the parking of vehicles such as trucks, buses, vans and the like.

and , while using the refined definition of “carpark”, also use the undefined expression “carparking”. This word specifically refers to the parking of cars. This is also the intention of refining the definition of “carpark” as expressed by the use of the words “specifically intended” in .

However, in applying these provisions, it is important to consider the purpose of refining this definition, which is to limit the concessions in Table 5.2 to areas used for the parking of lighter vehicles (that is, vehicles other than commercial trucks, vans, buses and the like), rather than simply limiting them to areas used for the parking of cars only.

Accordingly, it would seem contrary to the purpose of this clause to exclude, from the refined definition and the word “carparking”, such vehicles as motor bikes, van-like family vehicles, non-commercial panel vans, and smaller non-commercial utilities.

Regarding certain types of columns and beams, Table 5.2 permits them to have either a specified FRL or a specified surface area to mass ratio. In other words, in relation to these columns and beams, does not require them to have an FRL if they have the specified surface area to mass ratio. Some authorities refer to this ratio as the “heat sink effect”, in that the lower the exposed surface area to mass ratio, the lower will be the member temperature for a given fire.

In the section of Table 5.2 relating to columns:

the concession of (a) applies only to steel columns that are located less than 1.5 metres from any fire-source feature; and
the concession of (b) applies only to columns of any material which are located less than 1.5 metres from any fire-source feature.

Columns of any material that do not qualify for the (a) and (b) concessions are subject to (c).

Roofs that do not qualify for the roof concession in must comply with the requirements of for roofs of other buildings.

provisions restricting the roof concession to those roofs that are not used for carparking does not apply to .

The differences between and are based on the lower rise in storeys allowed for Type C buildings by .

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Specification C1.1 Fire-Resisting Construction

1. Scope

2. General Requirements

3. Type A Fire-Resisting Construction

Example

4. Type B Fire-Resisting Construction

Examples

Example

5. Type C Fire-Resisting Construction

Examples