Window and Glazing Requirements for Bushfire Prone Areas

What This Requirement Covers

Windows and glazing requirements for buildings in bushfire prone areas are intended to reduce the risk of external fire exposure igniting building interiors or finishes through failure of glazed openings during a bushfire event. These requirements control the selection, construction and installation of windows, glazed doors and other glazed assemblies so that they can resist ember attack, radiant heat and flame contact consistent with the assessed Bushfire Attack Level (BAL). They apply to new buildings, major renovations and certain ancillary structures located within designated bushfire prone areas.

The provisions are part of the National Construction Code (NCC) framework and associated guidance, and they are implemented primarily through the NCC Volume One (for Classes 2-9) and NCC Volume Two together with the ABCB Housing Provisions (for Class 1 and 10). Australian Standards referenced by the NCC and Housing Provisions (for example AS 2047, AS 1288 and AS 3959) provide detailed testing, design and glazing material guidance that supports the deemed-to-satisfy solutions. Compliance is required by builders, designers, certifiers and homeowners where the site is within a designated bushfire prone area.

Key Requirements

1. Design basis: windows and glazed assemblies in a bushfire prone area must be designed with regard to the assessed Bushfire Attack Level (BAL) for the site as determined under AS 3959 - Construction of buildings in bushfire-prone areas (see NCC Volume One Part G5 / state bushfire provisions and NCC Volume Two referencing Part H7D4 for housing).
2. Glazing vulnerability: glazing is a point of vulnerability for ember entry, flaming and radiant heat transfer; required treatments increase with higher BAL (BAL-LOW, BAL-12.5, BAL-19, BAL-29, BAL-40, BAL-FZ). Specific NCC/Housing Provisions and AS 3959 guidance determine acceptable glazing at each BAL.
3. Framing and tested systems: where windows are required to resist wind and bushfire actions they must meet the appropriate design and test standards: AS 2047 (performance of windows and external glazed doors) and AS 1288 (selection and installation of glass in buildings) as referenced in NCC Volume Two, Part 8.3 of the ABCB Housing Provisions. Cite: NCC Volume Two, Part 8.3; ABCB Housing Provisions Part 8.1.1.
4. Glazing types and limits: safety glazing and glass types must be used where human impact or bushfire exposure necessitates. The ABCB Housing Provisions require glass to be of a type within the scope of AS 1288 and safety glass marked in accordance with Part 8.4. Cite: ABCB Housing Provisions 8.3.1 and 8.3.2.
5. Tested assemblies and ember protection: for elevated BALs, AS 3959 describes appropriate construction and protection systems for openings (including the use of non-combustible shutters, flyscreens of metal mesh, or toughened/laminated glass and robust framing). NCC Volume One G5 (and state G5 variants) requires design to reduce ignition risk and maintain structural integrity for the design bushfire. Cite: NCC 2022 Volume One, Part G5; AS 3959.
6. Dimensions and numerical values (examples and typical limits):
7. Glass maximum area for some monolithic annealed types: for example, 3 mm monolithic annealed glass maximum area 0.85 m2 where specified in ABCB Housing Provisions 8.3.2 (note: other glass thicknesses and types have different limits under AS 1288 and AS 2047). Cite: ABCB Housing Provisions 8.3.2.
8. Wind and structural loading: glazing used in perimeter walls must be designed to resist relevant wind actions per AS 1170.2 and must comply with AS 2047 for design, testing and manufacture of windows where applicable. Cite: NCC Volume Two, H1P1 references and ABCB Housing Provisions 8.3.1(e), NCC Volume Two references to AS 2047.
9. Human impact: glazed assemblies subject to human impact must be designed and installed in accordance with AS 1288 and AS 2047, or Part 8.4 of ABCB Housing Provisions. Cite: NCC Volume Two, H1P1(3) and ABCB Housing Provisions Part 8.4.

Note: The NCC and Housing Provisions set out performance requirements and refer to specific Australian Standards and AS 3959 for bushfire design. Exact glazing requirements at each BAL are derived from AS 3959 and state variations; designers must reference the BAL assigned to the site and the associated clauses in AS 3959 and NCC Part G5/H7D4.

Residential vs Commercial

1. Residential (Class 1 and 10):
2. NCC Volume Two and the ABCB Housing Provisions are the primary references. Part 8.3 and Part 8.4 of the ABCB Housing Provisions set glazing selection, safety glass marking and human impact provisions for Class 1 and 10 buildings. Cite: ABCB Housing Provisions 8.1.1, 8.3.1.
3. Housing provisions explicitly apply limitations such as the 3 mm monolithic annealed glass maximum area 0.85 m2 example and require glazing to be within the scope of AS 1288. Glazing in housing must also satisfy bushfire-specific provisions in H7D4 when located in designated bushfire prone areas. Cite: ABCB Housing Provisions 8.3.2; NCC Volume Two H7D4.
4. Commercial and other classes (Class 2-9):
5. NCC Volume One (Part G5 for bushfire prone areas) applies to Classes 2-9 where the building is in a designated bushfire prone area; these provisions require the building to be designed to resist ignition from the design bushfire and refer to AS 3959 for construction detailing of external elements including windows where relevant. Cite: NCC 2022 Volume One Part G5.
6. For commercial glazing, AS 2047 and AS 1288 requirements are more frequently invoked for tested window systems, larger shopfronts, curtain walls and specialised glazed assemblies. The design must consider higher dead and live loads, larger pane sizes and different framing systems relative to housing. Cite: NCC Volume Two references to AS 2047 and AS 1288.

In short: Class 1/10 use the Housing Provisions (ABCB) with simplified deemed-to-satisfy paths; Classes 2-9 rely on NCC Volume One performance and referenced standards with more rigorous tested-system requirements for larger glazed areas.

Exceptions and Exemptions

1. Low-risk situations: BAL-LOW (or areas not designated as bushfire prone) do not impose specific bushfire glazing upgrades beyond normal NCC glazing and safety provisions. Cite: AS 3959 BAL definitions and NCC state provisions.
2. Minor building works: some small or replacement windows that do not increase risk may be able to follow standard glazing provisions in the ABCB Housing Provisions or NCC Volume Two instead of full AS 3959 measures, subject to local authority agreement. Cite: ABCB Housing Provisions applicability notes.
3. Alternative solutions: where deemed-to-satisfy solutions are impractical, a documented performance solution may be accepted under the NCC provided objective evidence (testing, engineering judgement or BAL-specific design) demonstrates equivalent bushfire resistance. Cite: NCC performance provisions (NCC Volume One and Volume Two governing requirements).
4. State-specific exemptions: some states include specific schedule provisions that modify national requirements for particular building classes or situations; always check the relevant state schedule in NCC Volume One (Schedules 4-12) and ABCB Housing Provisions state schedules. Cite: NCC Volume One state schedules guidance.

State and Territory Variations

1. The NCC requires checking state and territory schedules because jurisdictions may modify or add provisions affecting bushfire requirements. Cite: NCC Volume One Schedules 4-12 and ABCB Housing Provisions application notes.
2. Example - New South Wales: NSW inserts its own G5 provisions (NSW G5P1, NSW G5P2) that require buildings in designated bushfire prone areas to be designed to reduce ignition risk from the design bushfire and specify the classes to which the provisions apply. Cite: NCC 2022 Volume One - NSW G5P1.
3. Other jurisdictions: Queensland, Victoria, South Australia, Western Australia, Tasmania, ACT and Northern Territory may have schedule amendments or supplementary requirements affecting how BALs and glazing treatments are applied. Always consult the state schedule in the current NCC edition and any state planning or bushfire building guides.

Practical Compliance Tips

1. Check the site BAL first: determine the correct Bushfire Attack Level (BAL) under AS 3959 before specifying glazing or window systems - this single variable drives most glazing requirements.
2. Use tested window systems: specify windows and glazed doors tested to AS 2047 with documented performance for wind and water as well as appropriate glass types per AS 1288 to avoid on-site noncompliance.
3. Prefer non-combustible protection for high BALs: for BAL-29 and BAL-FZ consider non-combustible shutters, metal flyscreens, or removing vulnerable glazing where practicable in accordance with AS 3959 guidance and NCC G5 requirements.
4. Mind glass type and thickness limits: do not assume a single glass type is acceptable for all openings - verify maximum sizes, required laminations or toughened glass per AS 1288 and the ABCB Housing Provisions (e.g., 3 mm monolithic annealed glass max 0.85 m2 where referenced).
5. Record and cite standards on plans: show BAL, referenced standards (AS 3959, AS 2047, AS 1288), and NCC clause references on specification documents and certification forms so certifiers and builders can verify compliance.
6. Check state schedules early: review the relevant state schedule in NCC Volume One and any local bushfire or planning overlays to identify additional requirements such as NSW G5 variations before design finalisation.
7. Use performance solutions where needed: if the deemed-to-satisfy path is impractical, prepare a robust performance solution with test reports, engineering calculations and explicit cross-references to NCC performance requirements and state variations.

References cited inline: NCC 2022 Volume One - Part G5 (and NSW G5P1 example), NCC 2022 Volume Two - H1P1 and H7D4 references, ABCB Housing Provisions 8.1.1, 8.3.1 and 8.3.2, AS 3959 - Construction of buildings in bushfire-prone areas, AS 2047 - Windows in buildings, AS 1288 - Selection and installation of glass in buildings, AS 1170.1/2 for structural and wind actions.

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