Fire Exit and Egress Requirements for Multi-Storey Buildings

What This Requirement Covers

These provisions set out the minimum fire exit and egress requirements for multi-storey buildings under the National Construction Code (NCC) / Building Code of Australia. They exist to ensure occupants can escape safely and quickly in a fire or other emergency by specifying the number and distribution of exits, maximum travel distances, widths and construction of exit components (corridors, doors, ramps, stairs and discharge paths), and when fire-isolated egress is required. The rules apply to designers, builders, certifiers and building owners responsible for Class 2-9 buildings and parts of buildings that are not solely single dwellings or exempted Class 1/10 structures.

The objective is life safety through redundancy and separation of escape routes so that a single fire or hazard will not prevent safe evacuation. Requirements are primarily located in NCC Volume One, Part D2 (Provision for escape) together with Part D3 (Construction of exits) and associated deemed-to-satisfy provisions; Australian Standards such as AS 1428.1 (access and egress), AS 1657 (fixed platforms, walkways, stairways and ladders) and AS 1684/AS 3700 are commonly referenced where specific construction, access or structural criteria are needed.

Key Requirements

1. Number of exits: In general, each storey must have not less than one exit; where conditions in D2D3 require additional exits, two or more are required (for example, where a storey has a rise in storeys > 1.5 m with certain floor areas or where building classification or occupant loads trigger further exits). See NCC Volume One, Part D2, especially Clause D2D3.
2. Basement concession: Basements that involve a vertical rise within the building of more than 1.5 m require at least two exits, unless the floor area is ≤ 50 m2 and travel distance to a single exit is ≤ 20 m (NCC Volume One, D2D3).
3. Travel distance to exits: Maximum permitted travel distances depend on building use, whether paths are fire-isolated and other factors. Measure travel distance as specified in D2D6-D2D14 (along the path of travel, past seating, along stair nosings, etc.)-the NCC describes the method of measurement in detail (NCC Volume One, D2D6 and related clauses).
4. Exit separation: Alternative exits must be distributed and separated. Some jurisdictions adopt specific minimum separations (for example SA D2D6 requires alternative exits not less than 9 m apart and generally not more than 45 m or 60 m apart depending on building class). See NCC Volume One, D2D6 and applicable state variations.
5. Width of exits and paths of travel: Exit widths are set against occupant numbers and must provide required aggregate widths. For many egress routes the minimum unobstructed width is governed by occupant loading calculations (see D2D8 and D2D18). Example jurisdictional variation: NSW D2D8(5) for entertainment venues sets aggregate width not less than 2.0 m plus 500 mm for every 50 persons or part in excess of 200 (NCC Volume One, D2D8; NSW variations).
6. Stairs and ramps: Non-fire-isolated stairways measure travel along nosings; non-fire-isolated stairs providing multiple exits must discharge separately to a road or open space and be suitably smoke-separated (NCC Volume One, D2D14). Ramps discharging to road/open space must have gradient not steeper than 1:8, or 1:14 when required by Part D4 (NCC Volume One, D2D15(3)).
7. Discharge and external path: Where an exit leads to open space, the path to the road must have an unobstructed width of not less than the required exit width or 1.0 m, whichever is greater; discharge must not be blocked and vehicle protection may be required (NCC Volume One, D2D15).
8. Special spaces and exemptions: Plant rooms, lift machine rooms and small plant spaces may use ladders instead of stairs where floor areas meet the concessions (e.g., plant rooms ≤ 100 m2, certain lift machine rooms and Class 8 substations ≤ 200 m2) and AS 1657 applies to those ladders (NCC Volume One, D2D21; AS 1657).
9. Smoke separation and fire isolation: Non-fire-isolated stairs serving as multiple required exits must provide separate egress to road/open space and be suitably smoke-separated at discharge level; fire-isolated stair shafts and ramps have specific construction requirements in Part D3 (NCC Volume One, D2D14 and D3 clauses).
10. Occupant load calculations: Required widths, number of exits and some travel distance limits are triggered by occupant numbers calculated under Clause D2D18 (NCC Volume One, D2D18).
11. Relevant Australian Standards: Design and construction details must be in accordance with applicable standards such as AS 1428.1 for accessibility and door/route clearances, AS 1657 for ladders and fixed access, AS 1684 for timber framing where relevant, AS 4100 for steel structures and AS 3700 for masonry where construction affects egress routes.

Residential vs Commercial

1. Residential (Class 1 and 10): Single dwelling houses (Class 1a) and associated non-habitable outbuildings (Class 10) are generally outside the main Part D2 multi-storey egress provisions applied to multi-occupancy and multi-storey buildings. Where multiple dwellings (Class 2) or mixed-use residential buildings are involved, the full Part D2 requirements apply. For small private dwellings the NCC Volume Two (Housing Provisions) contains relevant egress provisions; see NCC Volume Two, Section 6.3.5 and the ABCB Housing Provisions for specific residential details.
2. Commercial and multi-occupancy (Class 2-9): These building classes are subject to the full Part D2 and D3 requirements in NCC Volume One. Commercial buildings commonly trigger stricter rules for number of exits, separation distances, travel distances, occupant-based exit widths and fire-isolated stair shafts. Examples: Class 9a health-care, Class 9b assembly and Class 5 offices have specific exit-number triggers tied to storey height, effective height and occupant loads (NCC Volume One, D2D3 and state variations such as NSW D2D3).

Exceptions and Exemptions

1. Small plant rooms, lift machine rooms and certain Class 8 electricity network substations may use ladders in lieu of stairs when below specified floor area thresholds (e.g., 100 m2 or 200 m2), provided ladders comply with AS 1657 and the conditions in D2D21 are met (NCC Volume One, D2D21).
2. Basements with floor area ≤ 50 m2 and travel distance to a single exit ≤ 20 m may be permitted a single exit despite vertical rise > 1.5 m (NCC Volume One, D2D3).
3. State and territory schedules may introduce concessions or additional requirements that override or modify the national Deemed-to-Satisfy provisions; these are treated as exceptions in those jurisdictions. Always check the relevant state schedule in NCC Volume One (Schedules 4-12).
4. Alternative solutions: Where deemed-to-satisfy provisions cannot be met, a performance solution demonstrated by fire engineering and approved by the regulator may be accepted. This requires documented fire-engineering analysis and certifier approval.

State and Territory Variations

1. NCC Volume One includes state and territory schedules that modify Part D provisions. Notable examples:
2. New South Wales: NSW D2D3(4) tightens exit requirements for Class 9 buildings - e.g., stores with rise in storeys > 6 or effective height > 25 m require not less than two exits; NSW also has specific exit width provisions for entertainment venues (see NSW D2D8(5)) (NCC Volume One, NSW Schedule clauses D2D3 and D2D8).
3. South Australia: SA D2D6 alters distance between alternative exits with minimum separation 9 m and maximum separations of 45 m, 60 m or other values depending on class (NCC Volume One, SA Schedule D2D6).
4. Other states have their own insertions or deletions to Part D that affect exit numbers, separations and allowable travel distances. Always verify against the state schedule in NCC Volume One (Schedules 4-12) for the project jurisdiction.

Practical Compliance Tips

1. Calculate occupant load early - Occupant numbers determine exit widths and number of exits. Use Clause D2D18 calculations at schematic design to size corridors, doors and stair widths correctly.
2. Measure travel distance along the path - When checking compliance, measure along the actual egress path as defined in D2D6 (including around fixed seating or past walls) rather than in straight lines.
3. Separate alternative exits physically - Avoid designs that allow alternative paths to converge into a single corridor close to the exits; aim for separation distances and discharge separation early in layout planning (check state D2D6 variations).
4. Design stair discharge for smoke separation - If using internal non-fire-isolated stairs as multiple exits, ensure smoke separation at discharge-level and separate discharge routes to the street or open space per D2D14 and D2D15.
5. Check jurisdiction schedules - Before finalising drawings, always check the applicable state schedule in NCC Volume One for local modifications (e.g., NSW, SA) that may change exit counts, separations or widths.
6. Use accessible dimensions - Ensure corridors and doors meet AS 1428.1 clearances and turning spaces so egress is usable by persons with disability; incorporate ramp gradients per Part D4 where discharge ramps are necessary.
7. Document alternative solutions - If using performance-based solutions (fire engineering), include full analysis, assumptions, and a certificate from the responsible fire engineer and discuss the proposal with your certifier early to avoid rejection.

References: NCC 2022 Volume One - Building Code of Australia, Part D2 Provision for escape and related clauses (D2D3, D2D6, D2D8, D2D14, D2D15, D2D18, D2D21), state schedule variations (e.g., NSW D2D3, NSW D2D8, SA D2D6) and Australian Standards including AS 1428.1, AS 1657, AS 1684, AS 4100 and AS 3700 for construction and accessibility details.

Could not determine: false