Fire sprinklers in Class 2 and 3 buildings

The following FRNSW guidance provides an explanation of the National Construction Code (NCC) requirements for a fire sprinkler system in applicable buildings, being any building that contains any Class 2 or 3 part, has a rise in storeys of four or more and an effective height of not more than 25 m, but excludes a residential care building.

Note: All Class 2 and 3 buildings more than 25 m effective height, and all Class 3 residential care buildings, require an AS 2118 fire sprinkler system throughout the building.

A building is to be classified as per Part A6 of NCC. Therefore a ‘Class 2 or 3 building’ is not inclusive of any other building classification unless that class is otherwise exempted (e.g. the other building classification is less than 10% of the floor area of the storey on which it is contained). Any other building that contains Class 2 or 3 parts is a multiple classification building.

Deemed-to-Satisfy provisions

For any applicable building, the fire sprinkler system must:

  • be installed in the whole building.  [NCC 2022: E1D6(1)]
  • comply with both Specification 17 and Specification 18 as applicable.  [NCC 2022: Clause E1D4(b)]

Application of standards under Specification 17  [NCC 2022: S17C2(b)]

For any applicable Class 2 or 3 building (i.e. does not contain any other Class, including Class 5, 6, 7, 8, 9a or 9b part):

  • The installed fire sprinkler system must comply with Specification 18 being either:
    • AS 2118.1  [NCC 2022: S18C3 (1)(a)]
    • AS 2118.4  [NCC 2022: S18C3 (1)(b)]
    • FPAA101D  [NCC 2022: S18C3 (1)(c)]
    • FPAA101H  [NCC 2022: S18C3 (1)(d)]

Note: The AS 2118.4 sprinkler system is only permitted in a four storey building. 

For any applicable multiple classification building (i.e. does contain a Class 5, 6, 7, 8, 9a or 9b part):

  • The installed fire sprinkler system may comply with either:
    • AS 2118.1  [NCC 2022: S17C2 (a)]
    • FPAA101H  [NCC 2022: S17C2 (c)]
    • FPAA101D  [NCC 2022: S17C2 (c)(i)]
    • AS 2118.6  [NCC 2022: S17C2 (d)]
    • AS 2118.4  [NCC 2022: S17C2 (f)]

Note: The AS 2118.4 sprinkler system is only permitted in a four storey building. 

An FPAA101D fire sprinkler system cannot be installed in a multiple classification building when the Class 5, 6, 7, 8, 9a or 9b parts:

  • contain more than 2 storeys; or
  • are more than 25% of the total floor area of the building; or
  • are located above the fourth storey.  [NCC 2022: S17C2 (c)(i)]

Note: The ‘parts’ are collective. By example, if a multiple classification building has ground level retail and two carpark storeys below ground, then it comprises three storeys of Class 5, 6, 7, 8, 9a or 9b parts, and the FPAA101D fire sprinkler system cannot be installed.

  • An FPAA101D or FPAA101H fire sprinkler system cannot be installed when the Class 7a part (except when open-deck) accommodates more than 40 vehicles.  [NCC 2022: S17C2 (c)(ii)]

Note: This provision does not specify vehicles within a fire compartment, therefore relates to the number of vehicles within the whole building. If the building accommodates more than 40 vehicles, then an appropriate AS 2118 sprinkler system is to be installed within the carparking areas.

For all applicable buildings:

  • Except for an FPAA101D system, the fire sprinkler system must be connected to and activate a building occupant warning system.  [NCC 2022: S17C8]
  • The relevant standard of performance for the fire sprinkler system installed must be clearly identified on the fire safety schedule for the building, including the standard as being applied under Specification 17 and Specification 18.
  • The permitted concessions under Specification 18 do not apply to a multiple classification building, including the dry internal fire hydrant concession. As a wet fire hydrant system is required, FRNSW recommends the FPAA101H system (or better) be installed in such buildings.

Permitted concessions under Specification 18

Specification 18 sets out the requirements for the design and installation of fire sprinkler systems for any applicable building only containing Class 2 or 3 parts.

Note: The permitted concessions under Section 3 of Specification 18 do not apply to any building having multiple classifications, that contains any other Class, including a Class 5, 6, 7, 8, 9a or 9b part.

For any applicable building that only contains Class 2 or 3 parts and is protected by either an AS 2118.1 or AS 2118.4 fire sprinkler system:

  • The concessions permitted under S18C4(1) only apply if:
    • the fire sprinkler system is connected to a fire alarm monitoring system connected to the fire brigades if the fire sprinkler system has more than 100 sprinkler heads, and  [NCC 2022: S18C3 (2)(a)(i)]
    • fire sprinklers are installed within bedrooms complying with given clauses from AS 2118.4  [NCC 2022: S18C3 (2)(b)]
    • an automatic smoke detection and alarm system is installed but not connected to a monitored automatic fire alarm system, and  [NCC 2022: S18C3 (2)(c)]
    • fire orders are provided in a Class 3 building in accordance with G4.9 as for a building in an alpine area.  [NCC 2022: S18C3 (2)(e)]
  • The concessions permitted by S18C4 (1) include:
    • reduced Fire Resistance Levels  [NCC 2022: S18C4 (1)(a), (b) and (c)]
    • increased travel distance  [NCC 2022: S18C4 (1)(d) and (e)]
    • increased distance between alternative exits  [NCC 2022: S18C4 (1)(f)]
    • removal of required internal fire hydrants or substitution with a dry-riser fire hydrant system which includes performance concessions, and  [NCC 2022: S18C4 (1)(g)]
    • removal of emergency warning and intercom system in a residential care building fitted with public address facility.  [NCC 2022: S18C4 (1)(h)]

For any applicable building only containing Class 2 or 3, that is protected by an FPAA101D fire sprinkler system, the concessions permitted by S18C4 (2) include:

  • removal of window opening protection  [NCC 2022: S18C4 (2)(a)]
  • reduced Fire Resistance Levels  [NCC 2022: S18C4 (2)(b)]
  • increased travel distance  [NCC 2022: S18C4 (2)(c) and (d)]
  • increased distance between alternative exits, and  [NCC 2022: S18C4 (2)(e)]
  • removal of required internal fire hydrants or substitution with a dry-fire hydrant system which includes performance concessions.  [NCC 2022: S18C4 (2)(f) and (g)]

For any applicable building only containing Class 2 or 3, that is protected by an FPAA101H fire sprinkler system, the concessions permitted by S18C4 (3) include:

  • removal of window opening protection  [NCC 2022: S18C4 (3)(a)]
  • reduced Fire Resistance Levels  [NCC 2022: S18C4 (3)(b)]
  • increased travel distance, and  [NCC 2022: S18C4 (3)(c) and (d)]
  • increased distance between alternative exits.  [NCC 2022: S18C4 (3)(e)]

 

Performance solutions for buildings containing Class 2 or 3 parts

The guidance above outlines the relevant performance requirements and Deemed-to-Satisfy (DtS) provisions outlined in the NCC for the fire sprinkler system in any applicable building containing Class 2 and 3 parts. Any performance solution proposed must demonstrate that the the design of the building, including the automatic fire suppression system, satisfies the performance requirements using an acceptable assessment method.

Under section A2G2 (3)(b) of the NCC, when a performance solution impacts upon any other performance requirements then the solution must demonstrate all affected performance requirements are also being satisfied. For example, concessions to the hydrant system under Specification 18 may impact on performance requirement E1P3, which is generally satisfied by complying with the corresponding DtS provisions (i.e. complying with AS2419.1); a performance solution should demonstrate that performance requirement E1P3 (and any other relevant performance requirements) is still being satisfied even when any sprinkler system concession is being applied.

FRNSW will be applying the interpretation and guidance provided above when assessing fire sprinklers in any building containing Class 2 or 3 parts.