Class 9a buildings are typically health care buildings, including public or private hospitals, nursing home or similar for sick or disabled people requiring full time care and Clinics.
Fire safety in a building can be improved by either
(a) By preventing the spread of fire from the compartment of origin to other parts of the building.
In a Class 9a building the objective is to limit the size of any fire in the building by limiting the floor area and volume of the fire compartment, and to limit fire spread between different building classifications or uses.
The purpose of this objective is to minimise the potential fire size as well as to ensure that occupants have sufficient time to evacuate a building in an emergency. Different office tenancies within the building do not necessarily need to have fire separation between them.
To achieve this objective elements of construction are required to achieve a certain fire resistance level and a critical aspect of construction is to ensure that construction joints and penetrations for services are adequately sealed.
(b) Using materials that are less likely to burn to minimise the likelihood of fire spreading as well as the generation of smoke and toxic gases. This objective is achieved by ensuring materials satisfy required early fire hazard indices, or are non-combustible.
This is of critical importance in a fire isolated stairway or passageway, which are relied upon in an emergency by occupants seeking egress from the building as well as for fire brigade intervention.
To minimise the spread of fire, fire growth as well as safety of occupants and emergency personnel in the event of a fire a building must be constructed so as to satisfy the requirements of
- Section C of the Building Code of Australia (BCA)
- Manufacturer’s Specification to ensure that the product performs as tested
If any of the above requirements cannot be met either because of innovative development or there is a particular construction issue, the building would not comply the Deemed-to Satisfy Requirements of the Building Code of Australia and consequently a Construction Certificate or an Occupation Certificate will not be able to be issued.
To overcome this situation the an Alternative Solution may be able to be prepared in accordance with Clause A0.8, A0.9, & A0.10 of the BCA, demonstrating that the method of construction will satisfy the Performance Requirements of Section C:
- Providing evidence that the form of construction satisfies the BCA;
- Using a Verification Method as set out in the BCA such as CV1 & CV2 to avoid spread of fire between buildings;
- Comparison with the Deemed-to-Satisfy provisions
- Expert judgement
General Deemed-to-satisfy Requirements
To satisfy the Deemed-to-Satisfy provisions of the BCA with respect to insulation or sarking, the designer must ascertain:
- If the insulation is required as part of a building element system requiring a fire resistance level (FRL)
- Whether the product is combustible
- The products early fire hazard properties;
- Which product to use in which specific situation
It is critical to understand that no single product can be used in all situations. Each product has its own performance characteristics in fire situation. Clause A2.2 of the BCA provides the methodology for determining the suitability of a particular material or form of construction. Specification A2.3 of the BCA sets out the procedures for determining the FRL of building elements and Specification A 2.4 of the BCA sets out the procedures for establishing a materials fire hazard properties.
Therefore to demonstrate that a product such as insulation or sarking is suitable to be used in a building it would have to have been tested by a registered testing authority and have some form of certification or accreditation, otherwise the installer will not be able to demonstrate that the product satisfies the requirements of the BCA.
Consequently the designer must familiarise themselves with the manufacture’s specification to ensure that the product will perform as it was tested to ensure that the work will satisfy the requirements of the BCA.
Deemed-to-satisfy Requirements Fire Resistance Levels
The type of fire-resisting construction that a building requires is primarily dependant on risk levels associated with the building’s classification (use) and the height (rise in storeys).
There are three levels or ‘types’ of fire-resisting construction being Type A construction which is the most fire-resistant, Type B which is an intermediate level of fire-resistant construction and Type C which is the least fire-resistant of the Types of construction. To determine the type of construction required for your building, see the following table:
In a building of multiple classifications, the classification of the top storey is used in the above Table to determine the type of construction required throughout the entire building.
Also the maximum floor areas and volumes allowed within the building is stipulated in BCA Table C2.2 and is dependant on the required type of construction and classification of the building.
As Class 9a buildings contain occupants who often require assistance to evacuate, it is important to further limit potential fire to small areas of the building. Accordingly, BCA Clause C2.5 requires further fire & smoke compartmentation of the building within patient care areas, ward areas and treatment areas. See BCA Clause C2.5 for full details.
There are further requirements and concessions under Section C and Specification C1.1 of the BCA that must also be considered to determine the final type of fire-resisting construction required for your building.
Once the final type of fire-resisting construction has been determined, then the fire resistance levels or “FRLs” of the various building elements of your building can be determined using Specification C1.1 of the BCA and the Tables contained therein. This Specification also contains certain limitations on building elements requiring them to be either concrete or masonry, non-combustible or contain certain risk fire hazard properties. Please refer to Specification C1.1 for further information.
The Fire Resistance Level (FRL) relates to the period in minutes that a system will resist the effects of fire with respect to the following criteria;
- Structural adequacy – where the system will still maintain its design load
- Integrity – where the system will not allow fire to pass
- Insulation – where the system insulates against heat passing through the total configuration
The FRLs are expressed as Structural adequacy/ Integrity/ Insulation and are shown in minutes eg 60/60/60. Where a dash is used, eg -/60/60 this means the FRL does not require a level for this property, being Structural Adequacy in this case.
The following is a list of the FRL for this building
Deemed-to-satisfy Requirements Early Fire Hazard Properties
It is important that the spread of fire and the development of smoke be limited during a fire until building occupants have had time to evacuate. Floor materials and floor coverings, and wall and ceiling linings must comply with Specification C1.10a. Refer to specification C1.10a for further detail outlining the fire hazard properties required for various lining materials as well as the testing that is required to support the use of a lining material.
Care should be taken if proposing to use exposed wall or ceiling insulation linings inside a Class 9a building, as they must comply with the fire hazard properties of Specification C1.10a. If the insulation does not meet the fire hazard properties of C1.10a, it must be ‘protected’ with a composite material to instead satisfy Specification C1.10.
In a Class 9a building all other materials and composite forms of construction (ie, apart from linings)must satisfy Specification C1.10, ie have a Spread-of-Flame Index not greater than 9; and Smoke-Developed Index not more than 8 if the Spread-of-Flame Index is more than 5. An example of composite construction would be plasterboard walls with insulation between wall sheets.
Otherwise the material will have to be completely covered on all faces by concrete or masonry not less than 50 mm thick.
However in a corridor leading to a fire isolated exit a material used as a finish, surface, lining or attachment to any wall or ceiling in a public corridor which is a means of egress to a fire isolated stairway, passageway or ramp the material must have a Spread-of-Flame Index of 0 and a Smoke-Developed Index of not more than 5;.
The fire hazard properties of duct work must comply with the fire hazard properties required by AS 4254 such as Clause 2.7 which in general states that insulation used for ducts liners must have a smoke developed index of not greater than 3 and spread of Flame index of 0 (refer to standard for complete details).
Deemed to Satisfy Requirement for Sarking
Clause C1.10 of the BCA states that the fire hazard properties of any material must comply with Specification C1.10 or Specification C1.10a of the BCA. Specification C1.10 Clause 2 (a) states that a sarking-type of material must have a Flammability Index that does not exceed 5. However in a Fire isolated exit a sarking type material must have a Flammability Index that does not exceed 0.
Deemed to Satisfy Requirement for Sealing Penetrations
For a building to properly function services are often required to penetrate elements of construction required to have a fire resistant level (FRL). To prevent the spread of fire via the services, these penetrations must be capable of maintaining the require FRL with respect to integrity and insulation.
Specification C 3.15 of the BCA states that a material used for fire sealing service penetrations must be either:
- Concrete, or
- High-temperature mineral fibre or high-temperature ceramic fibre or
- Another material that does not flow at a temperature below 1120°C when tested in accordance with AS 1038.15, the system as tested does not impair the fire-resisting performance of the building element in which it is installed;
The fire-stopping material must be packed into the gap between the service and wall, floor or ceiling in a manner, and compressed to the same degree, as adopted for testing
Where a pipe penetrates a hollow wall (such as a stud wall, a cavity wall or a wall of hollow blockwork) or a hollow floor/ceiling system, the cavity must be so framed and packed with fire-stopping material that provides a minimum cover of 25 mm all round the service for the full length of the penetration and is restrained so the insulation cannot fall from the service penetration.
For an electrical switch, socket, outlet or the like is accommodated in a recess in a hollow wall or hollow floor/ ceiling system the cavity immediately behind the service must be framed and packed with fire-stopping material
If a wire or cable or cluster of wires or cables penetrates a floor, wall or ceiling the gap between the service and the wall, floor or ceiling must be fire-stopped using material such as thermal insulation such as high-temperature mineral or ceramic fibre.
Deemed to Satisfy Requirement for Construction Joints
To avoid the spread of fire between fire compartments or to another building, construction joints between building elements are normally packed with fire retardant material with respect to of integrity and insulation. Clause C3.16 of the BCA does not require structural adequacy criteria to be achieved for construction joints.
Fore example the BCA requires that a wall required to have a fire resistance level that wall must extend to the underside of the floor above or a ceiling with a resistance to the incipient spread of fire for at least 60 minutes or the underside of the roof.
In each of these situations there will be a construction joint creating a gap between the top of the wall and the underside of the floor, ceiling or roof. This gap must be sealed to prevent the spread of fire by using a material that has maintains its integrity as well as insulation prosperities in a fire scenario.
To ensure that the product used to seal these gaps it must have been tested and either a certificate of accreditation or a certificate of conformity. Clause C3.15 (a) of the BCA permits the use of tested systems. The appropriate authority can allow any complying tested service penetration without the need to refer to a test report, provided it is satisfied that “an adequate level of performance is maintained”.
A number of proprietary products are suitable for sealing construction joints, if they have been previously tested in accordance with AS 1530.4 to demonstrate they have achieved the required fire-resistance level (FRL).
Certificate of Accreditation
A Certificate of Accreditation is issued by a State or Territory accreditation authority and is evidence that a building material, method of construction or design (subject to any specified conditions or limitations) is accepted within that State or Territory as complying with the BCA. Certificates of Accreditation are no longer issued by the ABCB. Certificates issued by the ABCB under the previous scheme are no longer valid.
Certificate of Conformity
A Certificate of Conformity issued under the ABCB scheme is evidence that a building material, method of construction or design (subject to any specified conditions or limitations) is accepted within all States and Territories as complying with the BCA.
A test done in accordance with AS 1530.1 will determine if a material is combustible. If materials used in an assembly contain combustible components, then the assembly is combustible.
Applies to fire-resisting building elements, including structural members and non-loadbearing components, such as cladding, doors, windows and the like.
A test performed in accordance with AS 1530.2 will determine the flammability index of a material.
Habitable room means a room used for normal domestic activities, and—
(a) Includes a bedroom, living room, lounge room, music room, television room, kitchen, dining room, sewing room, study, playroom, family room and sunroom; but
(b) Excludes a bathroom, laundry, water closet, pantry, walk-in wardrobe, corridor, hallway, lobby, photographic darkroom, clothes-drying room, and other spaces of a specialised nature occupied neither frequently nor for extended periods
Insulation is the third criterion used when specifying an FRL.
Integrity is the second criterion used when specifying an FRL. See example under “insulation” definition.
The test under AS 1530.4 considers that a building element has failed the integrity criterion when either the element collapses, or the element develops cracks, fissures or other openings through which flames or hot gases can pass.
Clause C1.12 of the BCA lists materials deemed to be non-combustible. These materials may be used wherever a material is required to be non-combustible. In some instances the material may contain combustible components. The materials listed are not intended to apply to fire place hearths.
The following materials, though combustible or containing combustible fibres, may be used wherever a non-combustible material is required:
- Perforated gypsum lath with a normal paper finish.
- Fibrous-plaster sheet.
- Fibre-reinforced cement sheeting.
- Pre-finished metal sheeting having a combustible surface finish not exceeding 1 mm thickness and where the Spread-of-Flame Index of the product is not greater than 0.
- Bonded laminated materials where—
- Each laminate is non-combustible; and
- Each adhesive layer does not exceed 1 mm in thickness; and
- The total thickness of the adhesive layers does not exceed 2 mm; and
- The Spread-of-Flame Index and the Smoke-Developed Index of the laminated material as a whole does not exceed 0 and 3 respectively.
A test in accordance with AS/NZS 1530.3 determines the Spread-of-Flame Index of a material. The index is based on a logarithmic scale of 0 to 10. A lower index number indicates better performance.
Standard Fire Test
AS 1530.4 contains details of the Standard Fire Test. The test is used to determine the FRL of a building element. The results are recorded in order as: structural adequacy, integrity and insulation.
In relation to an FRL, means the ability to maintain stability and adequate loadbearing capacity as determined by AS1530.4.
Verification Method means a test, inspection, calculation or other method that determines whether a Building Solution complies with the relevant Performance Requirements.