Fire / BAL bushfire zones

Two different fire questions apply to timber floors: (1) internal fire hazard properties — CRF and Group Number — for NCC Class 2–9 buildings, and (2) external BAL rating for buildings in bushfire-prone areas per AS 3959. Both have explicit species lists in the corpus.

Mechanism

NCC Spec C1.10a (via BCA) requires floor materials and floor coverings to meet a Critical Radiant Flux per class of building, and wall/ceiling linings to have a Material Group Number per Table 2a. Timber Queensland TDS-30 tabulates: 19 mm T&G species with CRF ≥ 4.5 kW/m² (Table 1b), species with CRF between 2.2 and 4.5 kW/m² (Table 1c), and all species tested to Group 3 (Table 2b). For external bushfire zones, AS 3959-2018 assigns Bushfire Attack Levels (BAL-LOW, 12.5, 19, 29, 40, FZ) and Appendix F lists Bushfire Resisting Timbers.

Risk profile by species

SpeciesRiskNote & source
Blackbutt CRF 2.2–4.5 (Table 1c) / BRT-listed Blackbutt sits in Table 1c (CRF between 2.2 and 4.5 kW/m²) for internal fire. Also one of 7 species listed as Bushfire Resisting Timber in AS 3959 Appendix F.Source: tq-tds-30-fire-hazard-properties.pdf Table 1c + timber-in-bushfire-zones-fact-sheet-oct-2022.pdf
Spotted Gum CRF ≥ 4.5 (Table 1b) / BRT-listed Spotted Gum is in Table 1b (CRF ≥ 4.5 kW/m²) and listed as Bushfire Resisting Timber.Source: tq-tds-30-fire-hazard-properties.pdf Table 1b + timber-in-bushfire-zones-fact-sheet-oct-2022.pdf p.3
Red Ironbark CRF ≥ 4.5 (Table 1b) / BRT-listed Red Ironbark — Table 1b + AS 3959 Appendix F BRT.Source: tq-tds-30-fire-hazard-properties.pdf + timber-in-bushfire-zones-fact-sheet-oct-2022.pdf
Jarrah CRF ≥ 4.5 (Table 1b) Jarrah appears in Table 1b with CRF ≥ 4.5 kW/m²; not listed as BRT.Source: tq-tds-30-fire-hazard-properties.pdf Table 1b
Tallowwood CRF ≥ 4.5 (Table 1b) Tallowwood in Table 1b; also one of the Group 3 species in Table 2b.Source: tq-tds-30-fire-hazard-properties.pdf Tables 1b + 2b
Messmate CRF 2.2–4.5 (Table 1c) Messmate is in Table 1c (CRF between 2.2 and 4.5 kW/m²).Source: tq-tds-30-fire-hazard-properties.pdf Table 1c
Merbau CRF ≥ 4.5 (Table 1b) / BRT-listed Merbau (Kwila) is in Table 1b and is the easiest BRT to source per the WoodSolutions bushfire fact sheet.Source: tq-tds-30-fire-hazard-properties.pdf + timber-in-bushfire-zones-fact-sheet-oct-2022.pdf p.3

Mitigations

  • Determine BAL first (council-mapped or AS 3959 simplified/detailed method). For BAL-FZ, AS 3959 requires a bushfire consultant; NSW RFS approval is required.
    Source: timber-in-bushfire-zones-fact-sheet-oct-2022.pdf p.1
  • Above BAL-12.5, decking and framing within 400 mm of ground or deck surface must be Bushfire Resisting Timber; other elements may be Any Timber per the table.
    Source: timber-in-bushfire-zones-fact-sheet-oct-2022.pdf p.2
  • For internal (Class 2–9) floors use TQ TDS-30 Tables 1b / 1c to select species that meets the CRF threshold for the building class and sprinkler condition.
    Source: tq-tds-30-fire-hazard-properties.pdf Tables 1a–1c
  • traffic-hd
    Bona Traffic HD topcoat carries an EN 13501-1 Reaction-to-Fire certification, which can support specifier justification for lining systems.
    Source: Bona_TrafficHD_TDS_AU.pdf p.2

Bona product guidance

  • traffic-hd
    Certificates on TDS: EMICODE EC1 Very Low Emission, GREENGUARD Gold, EN 14904:2006 approved friction for sports floors, EN 13501-1 Reaction to Fire. Qualifies for LEED and BREEAM points.
    Source: Bona_TrafficHD_TDS_AU.pdf p.2

NCC / standards references

  • NCC Specification C1.10a (CRF for floors, Group Number for linings)
  • AS 3959-2018 Construction of buildings in bushfire-prone areas
  • AS ISO 9239.1 (CRF test)
  • AS ISO 9705 / AS NZS 3837 (Group Number)

Gaps in the corpus (no claim made)

  • AS 3959-2018 explicit Appendix F BRT list (only 7 species) is summarised in the WS fact sheet; full list may need independent citation from the standard itself.
  • Specific Cfl-s1 or equivalent EN 13501-1 class for Bona Traffic HD is cited as a certification in the TDS but the specific class letter is not reproduced in the TDS excerpt pulled.
Sources