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.
Spec C1.1 – 2 FIRE RESISTANCE
Clause 2.3 only applies to a lintel required by the Deemed-to-Satisfy Provisions to have an FRL.
Clauses 2.3(a) and (b) 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 Attachments not to impair fire-resistance Intent
To minimise the risk that a finish, lining or attachment to a wall or roof required to have a fire-resistance level (FRL) will:
• impair the FRL of the wall or roof to which it is attached;
• compromise the safe evacuation of the building; and
• lead to the spread of fire by way of the building facade.
Clause 2.4 does not prohibit the use of combustible materials as a finish, lining or other attachment to a wall, roof or other building element required to have an FRL.
However, the combustible material can only be used if the material:
• is one of the exemptions from fire hazard properties listed in C1.10(c), or complies with the fire hazard properties prescribed in Specification C1.10 (see Clause 2.4(a)(i));
• is not located in a position to make a required exit unusable in a fire, therefore it will not compromise the building's safe evacuation (see Clause 2.4(a)(ii));
• will not lead to the spread of fire by way of the building facade (see Clause attachment of facings or finishes or the installation of ducting or any other service.
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 Clause 2.5(a) 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 Clause 2.5(b) 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 Clause 2.5(c) are not likely to lead to the spread of fire, especially as they are required to be non-combustible. The intent of Clause 2.5(c)(ii)(E) 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 Clause 2.5(d) 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 A1.1.
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 Table 3, 4 or 5. 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 may be constructed from materials that do not have an FRL and/or are combustible.
Table 2.6 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
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.
Clause 2.7 complements other requirements for the walls of shafts by requiring that shafts be enclosed at the top and bottom by fire rated construction.
Spec C1.1 – 2 FIRE RESISTANCE
Clause 2.7 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 Clause 2.7(a)), or the bottom of the shaft is laid on the ground (see Clause 2.7(b)).
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.
Part A3 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 Specification C1.1.
This concession applies to buildings which are otherwise wholly Class 2, wholly Class 3 no more than 3 storeys (see Clause 2.8(b)(ii)).
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 D1.3.
The Clause 2.8 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 A1.1.
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 A3.2) meant that those concessions could not be used for many aged care hostels. The concessions in Clause 2.9 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 Clause 2.9(a) applies to the requirements for floors and loadbearing walls as set out in Tables 3, 4 and 5 of Specification C1.1. 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 Clause 2.9(b) for non-loadbearing internal walls, allows a reduction in FRLs subject to several conditions outlined in Clause 2.9(b). The conditions outlined in Clause 2.9(b) 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 Clause 2.9(b)(i)); 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 Clause 2.9(b)(ii)).
Clause 2.9(b)(iii) 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 C3.11(d)(ii), and walls must still comply with the requirements of Part F5—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 Intent
To specify the fire-resistance level (FRL) and other requirements for building elements in Type A construction.