NCC 2022 Volume One - Building Code of Australia Class 2 to 9 buildings
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1

Specification 1 Fire-resistance of building elements

Specification 1 Fire-resistance of building elements

Deemed-to-Satisfy Provisions often require building elements to have an FRL. Specification 1 explains how these FRLs are to be determined and, in conjunction with Tables S1C2a to S1C2n, outline how FRLs apply to specific building elements and materials.

This Specification sets out the procedures for determining the FRL of building elements.

To clarify that Specification 31 includes the requirements for fire and smoke control systems in buildings with an atrium.

Specification 31 includes the requirements for fire and smoke control systems in buildings containing an atrium. 
Where a sprinkler system is required, it must be installed in the whole building, not just that part in which the atrium is located.

A building element meets the requirements of this Specification if—

  1. it is listed in, and complies with Tables S1C2a, S1C2b, S1C2c, S1C2d, S1C2e, S1C2f, S1C2g, S1C2h, S1C2i, S1C2j, S1C2k, S1C2l, S1C2m or S1C2n of this Specification as applicable; or
  2. it is identical with a prototype that has been submitted to the Standard Fire Test, or an equivalent or more severe test, and the FRL achieved by the prototype without the assistance of an active fire suppression system is confirmed in a report from an Accredited Testing Laboratory which—
    1. describes the method and conditions of the test and the form of construction of the tested prototype in full; and
    2. certifies that the application of restraint to the prototype complied with the Standard Fire Test; or
  3. it differs in only a minor degree from a prototype tested under (b) and the FRL attributed to the building element is confirmed in a report from an Accredited Testing Laboratory which—
    1. certifies that the building element is capable of achieving the FRL despite the minor departures from the tested prototype; and
    2. describes the materials, construction and conditions of restraint which are necessary to achieve the FRL; or
  4. it is designed to achieve the FRL in accordance with—
    1. AS/NZS 2327, AS 4100 and AS/NZS 4600 if it is a steel or composite structure; or
    2. AS 3600 if it is a concrete structure; or
    3. AS 1720.4 if it is a timber element other than fire-protected timber; or
    4. AS 3700 if it is a masonry structure; or
  5. the FRL is determined by calculation based on the performance of a prototype in the Standard Fire Test and confirmed in a report in accordance with S1C3; or
  6. for fire-protected timber, it complies with Specification 10 where applicable.
Table S1C2a FRLs deemed to be achieved by walls — masonry
Masonry type Minimum thickness (mm) of principal material for FRLs
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240
Ashlar - - - - 300
Calcium silicate See clause S1C2(d)(iv)
Concrete
Fired clay
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2b FRLs deemed to be achieved by walls — concrete
Concrete type Minimum thickness (mm) of principal material for FRLs
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240
No fines - - - 150 300
Prestressed See clause S1C2(d)(iv)
Reinforced
Plain - - - 150 170
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2c FRLs deemed to be achieved by walls — gypsum
Gypsum type Minimum thickness (mm) of principal material for FRLs
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240
Solid gypsum blocks 75 90 100 110 125
Gypsum — perlite or gypsum vermiculite-plaster on metal lath and channel (non-loadbearing walls only) 50 50 65 - -
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2d FRLs deemed to be achieved by concrete columns
Column type Minimum thickness (mm) of principal material for FRLs
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240
Prestressed See clause S1C2(d)(ii)
Reinforced
Table S1C2e FRLs deemed to be achieved by hot-rolled steel columns (including a fabricated column) exposed on not more than 3 sides
Fire protection Minimum thickness (mm) of principal material for FRLs
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240
Concrete cast in-situ — loadbearing 25 30 40 55 75
Concrete cast in-situ — non-loadbearing unplastered 25 30 40 50 75
Concrete cast in-situ — non-loadbearing plastered 13 mm 25 25 30 40 50
Gypsum cast in-situ - - - - 50
Gypsum — perlite or gypsum-vermiculite plaster—sprayed to contour 20 25 35 50 55
Gypsum — perlite or gypsum-vermiculite plaster—sprayed on metal lath 20 20 25 35 45
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2f FRLs deemed to be achieved by hot-rolled steel columns (including a fabricated column) exposed on no more than 3 sides and with column spaces filled
Fire protection Minimum thickness (mm) of principal material for FRLs
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240
Solid calcium-silicate masonry 50 50 50 50 65
Solid clay masonry 50 50 50 65 90
Solid concrete masonry 50 50 50 65 90
Solid gypsum blocks 50 50 50 50 65
Hollow terracotta blocks — plastered 13 mm 50 50 50 65 90
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2g FRLs deemed to be achieved by hot-rolled steel columns (including a fabricated column) exposed on no more than 3 sides and with column spaces unfilled
Fire protection Minimum thickness (mm) of principal material for FRLs
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240
Solid calcium-silicate masonry 50 50 50 - -
Solid clay masonry 50 50 65 - -
Solid concrete masonry 50 50 65 - -
Solid gypsum blocks 50 50 50 - -
Hollow terracotta blocks — plastered 13 mm 50 50 65 - -
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2h FRLs deemed to be achieved by hot-rolled steel columns (including a fabricated column) exposed on no more than 4 sides
Fire protection Minimum thickness (mm) of principal material for FRLs
60/–/– 90/–/– 120/–/– 180/–/– 240/–/–
Concrete cast in-situ — loadbearing 25 40 45 65 90
Concrete cast in-situ — non-loadbearing unplastered 35 30 40 50 65
Concrete cast in-situ — non-loadbearing plastered 13 mm 25 25 30 40 50
Gypsum cast in-situ - - - - 50
Gypsum — perlite or gypsum-vermiculite plaster — sprayed to contour 25 30 40 55 65
Gypsum — perlite or gypsum-vermiculite plaster — sprayed on metal lath 20 20 30 40 50
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2i FRLs deemed to be achieved by hot-rolled steel columns (including a fabricated column) exposed on no more than 4 sides and with column spaces filled
Fire protection Minimum thickness (mm) of principal material for FRLs
60/–/– 90/–/– 120/–/– 180/–/– 240/–/–
Solid calcium-silicate masonry 50 50 50 65 75
Solid clay masonry 50 50 50 75 100
Solid concrete masonry 50 50 50 75 100
Solid gypsum blocks 50 50 50 65 75
Hollow terracotta blocks — plastered 13 mm 50 50 50 75 100
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2j FRLs deemed to be achieved by hot-rolled steel columns (including a fabricated column) exposed on no more than 4 sides and with column spaces unfilled
Fire protection Minimum thickness (mm) of principal material for FRLs
60/–/– 90/–/– 120/–/– 180/–/– 240/–/–
Solid calcium-silicate masonry 50 50 50 - -
Solid clay masonry 50 50 65 - -
Solid concrete masonry 50 50 65 - -
Solid gypsum blocks 50 50 50 - -
Hollow terracotta blocks — plastered 13 mm 50 50 65 - -
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2k FRLs deemed to be achieved by concrete beams
Concrete type Minimum thickness (mm) of principal material for FRLs
60/–/– 90/–/– 120/–/– 180/–/– 240/–/–
Prestressed See clause S1C2(d)(ii)
Reinforced
Table S1C2l FRLs deemed to be achieved by hot-rolled steel beams (including an open-web joist, girder, truss, etc.) exposed on no more than 3 sides
Fire protection Minimum thickness (mm) of principal material for FRLs
60/–/– 90/–/– 120/–/– 180/–/– 240/–/–
Concrete — cast in-situ 25 30 40 50 65
Gypsum — perlite or gypsum-vermiculite plaster — sprayed to contour 20 25 35 50 55
Gypsum — perlite or gypsum-vermiculite plaster — sprayed on metal lath 20 20 25 35 45
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2m FRLs deemed to be achieved by hot-rolled steel beams (including an open-web joist, girder, truss, etc.) exposed on 4 sides
Fire protection Minimum thickness (mm) of principal material for FRLs
60/–/– 90/–/– 120/–/– 180/–/– 240/–/–
Concrete — cast in-situ 25 40 45 60 90
Gypsum — perlite or gypsum-vermiculite plaster — sprayed to contour 20 30 40 55 65
Gypsum — perlite or gypsum-vermiculite plaster — sprayed on metal lath 20 20 35 40 50
Table Notes

For the purposes of this table, each element must meet the requirements of Specification 2.

Table S1C2n FRLs deemed to be achieved by floor, roof or ceiling
Floor, roof or ceiling type Minimum thickness (mm) of principal material for FRLs
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240
Prestressed See clause S1C2(d)(ii)
Reinforced

To set out the installation requirements and delineate compliance pathways for a building element to meet this Specification.

An FRL is expressed in terms of figures that cover structural adequacy, integrity and insulation.

Examples

A loadbearing wall may require an FRL of 120/60/30 – meaning that in the Standard Fire Test, the wall must retain its:

  • Structural adequacy for at least 120 minutes;
  • Integrity for at least 60 minutes; and
  • Insulation properties for at least 30 minutes.

A non-loadbearing wall, however, may require an FRL of -/120/120 – meaning that in a Standard Fire Test, the wall is not required to retain any structural adequacy criterion. However, in a Standard Fire Test, the wall must maintain its:

  • Integrity for at least 120 minutes; and
  • Insulation properties for at least 120 minutes.

Some building elements have been tested and their FRLs have been determined. A number of these are included in Tables S1C2a to S1C2n. To achieve the FRLs contained in tables S1C2a, S1C2b, S1C2c, S1C2e, S1C2f, S1C2g, S1C2h, S1C2i, S1C2j, S1C2l, and S1C2m each element must comply with Specification 2.

Research results are generally available from the manufacturers who sponsor the tests. 

A number of Standards Australia structural codes have provisions for the calculation of FRLs. Some more complicated building elements have many combinations and permutations, and reference to specific Australians Standards is necessary.

If the FRL of a building element is determined by calculation based on a tested prototype—

  1. the building element may vary from the prototype in relation to—
    1. length and height if it is a wall; and
    2. height if it is a column; and
    3. span if it is a floor, roof or beam; and
    4. conditions of support; and
    5. to a minor degree, cross-section and components; and
  2. the report must demonstrate by calculation that the building element would achieve the FRL if it is subjected to the regime of the Standard Fire Test in relation to—
    1. structural adequacy (including deflection); and
    2. integrity; and
    3. insulation; and
  3. the calculations must take into account—
    1. the temperature reached by the components of the prototype and their effects on strength and modulus of elasticity; and
    2. appropriate features of the building element such as support, restraint, cross-sectional shape, length, height, span, slenderness ratio, reinforcement, ratio of surface area to mass per unit length, and fire protection; and
    3. features of the prototype that influenced its performance in the Standard Fire Test although these features may not have been taken into account in the design for dead and live load; and
    4. features of the conditions of test, the manner of support and the position of the prototype during the test, that might not be reproduced in the building element if it is exposed to fire; and
    5. the design load of the building element in comparison with the tested prototype.

To establish methods for determining a building element's FRL by calculation using data from a similar tested prototype.

S1C3(a) contains permitted variations for when a building element’s FRL is determined by calculation based on a tested prototype that is similar. Required considerations for calculations are included in S1C3(c).

(1) Concrete and plaster — An FRL achieved with any material of Group A, B, C, D or E as an ingredient in concrete or plaster, applies equally when any other material of the same group is used in the same proportions:

  1. Group A: any portland cement.
  2. Group B: any lime.
  3. Group C: any dense sand.
  4. Group D: any dense calcareous aggregate, including any limestone or any calcareous gravel.
  5. Group E: any dense siliceous aggregate, including any basalt, diorite, dolerite, granite, granodiorite or trachyte.

(2) Perlite and vermiculite — An FRL achieved with either gypsum-perlite plaster or gypsum-vermiculite plaster applies equally for each plaster.

To provide further options for building element selection by providing interchangeable materials.

If the fire-resisting covering of a steel column is lightweight construction, the construction must comply with Volume One C2D9 and C4D17.

To clarify that lightweight construction used to protect steel columns must adhere to C2D9 and C4D17.

If a non-loadbearing element is able to be used for a purpose where the Deemed-to-Satisfy Provisions prescribe an FRL for structural adequacy, integrity and insulation, that non-loadbearing element need not comply with the structural adequacy criteria.

To specify that a non-loadbearing element need not meet any structural adequacy requirement.