NCC 2022 Volume One - Building Code of Australia Class 2 to 9 buildings
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10

Specification 10 Fire-protected timber

Specification 10 Fire-protected timber

This Specification contains requirements for fire-protected timber and procedures for determining the time at which the temperature at the interface between the protection system and the timber is exceeded.

Requirements

(1) Fire-protected timber must—

  1. utilise a non-combustible fire-protective covering fixed in accordance with the system requirements to achieve an FRL not less than that required for the building element; and
  2. have a non-combustible fire-protective covering fixed in accordance with system requirements—
    1. to achieve a resistance to the incipient spread of fire of not less than 45 minutes when tested in accordance with—
      1. for horizontal elements — Section 4 of AS 1530.4; and
      2. for other elements — the relevant test procedures from Section 4 of AS 1530.4 applied to the element lining; or
    2. which consists of not less than 2 layers of 13 mm thick, fire-protective grade plasterboard.

(2) For the purposes of (1), the non-combustible fire-protective covering provided under (1)(b) may form all or part of the non-combustible fire-protective covering provided under (1)(a).

(1) Fire-protected timber, where the timber is massive timber, need not comply with S10C2 if the fire-protected timber—

  1. utilises a non-combustible fire-protective covering fixed in accordance with system requirements to achieve an FRL not less than that required for the building element; and
  2. has a non-combustible fire-protective covering fixed in accordance with system requirements—
    1. so as the temperature at the interface between the protection system and the timber does not exceed 300°C during a fire resistance test performed in accordance with S10C4, S10C5 and S10C6 for the application and periods listed in Table S10C3; or
    2. not less than that specified by Table S10C3; and
  3. has any cavity filled with non-combustible insulation, or no cavity, between—
    1. the surface of the timber and the fire-protective covering; or
    2. timber elements within the fire-protective covering.

(2) For the purposes of (1), the non-combustible fire-protective covering provided under (1)(b) may form all or part of the non-combustible fire-protective covering provided under (1)(a).

Table S10C3 Interface temperature and minimum fire protective grade plasterboard thickness
Application Time – without timber interface exceeding 300°C (mins) Minimum thickness of fire-grade plasterboard (mm)
Inside a fire-isolated stairway or lift shaft 20 13
External walls within 1 m of an allotment boundary or 2 m of a building on the same allotment 45 2 x 13
All other applications 30 16

Determination of time the timber interface temperature exceeds 300°C for timber at least 75 mm thick

(1) Tests must be carried out in accordance with the Standard Fire Test, or an equivalent or more severe test, on the timber element with the proposed non-combustible coverings fixed in a representative manner, with the time the timber interface temperatures exceeded 300°C confirmed in a report from an Accredited Testing Laboratory.

(2) If a fire protection system incorporates joints, the test specimens must incorporate representative joints.

(3) Interface temperatures must be measured over the following features by a minimum of two thermocouples:

  1. At joint positions in the protection systems.
  2. At least 200 mm from any joint.
  3. At service penetrations.
  4. At any other locations where, in the opinion of the Accredited Testing Laboratory, the interface temperature may be higher than the above positions.

(4) The temperatures must be measured in accordance with Appendix C1 and Section 2 of AS 1530.4 as appropriate.

An Accredited Testing Laboratory may carry out the test specified in S10C4 at pilot scale provided—

  1. a specimen (which must be not less than 1000 mm x 1000 mm) adequately represents the proposed construction in the building; and
  2. the fire resistance of the specimen has already been determined in a full scale test performed in accordance with AS 1530.4 to demonstrate adequate retention of the fire protection system in conjunction with the timber elements being protected; and
  3. the results of the test do not apply to construction larger than limits defined by the Accredited Testing Laboratory conducting the pilot examination.

The time the timber interface temperature exceeds 300°C must be taken as the minimum time any of the thermocouples specified in S10C4 exceeded 300°C.