Change of Building Classification and Upgrade Requirements

What This Requirement Covers

A change of building classification occurs when a building, or part of a building, is adapted or proposed to be used for a different purpose than that for which it was originally designed or constructed. The National Construction Code (NCC) treats classification as the primary means of matching building safety, health, amenity and accessibility requirements to actual use. Where a change of use or change of classification takes place, the building or affected part must comply with the NCC requirements that apply to the new classification or to any part that now performs a different function.

This requirement exists to manage risk: different occupancies have different fire, egress, structural loading, services and access requirements. It applies to owners, developers, designers and certifiers proposing or assessing a change of use or reclassification of an entire building, a storey, or a discrete part of a building. Both renovations and adaptive reuse projects must consider whether upgrades are required so the altered part meets the NCC provisions for the new classification, or whether exemptions or staged upgrades apply.

Key Requirements

1. Determining classification: The building or part must be classified according to the purpose for which it is designed, constructed or adapted to be used (NCC 2022 Volume One and Volume Two, Part A6 - Governing Requirements and A6G1 Determining a building classification).
2. Whole or part compliance: Each part of a building must comply with all requirements for its classification; where conflict exists the more stringent requirement applies (NCC Volume One, A6G1(2)).
3. Minor use exemption: If a part of a storey is adapted to a different purpose but is less than 10% of the floor area of that storey, the classification of the remainder of the storey may apply to the whole storey (NCC Volume One and Volume Two, A6G1 Exemptions). Limitations: the 10% concession does not apply where the minor use is a laboratory, a Class 9b early childhood centre, or a Class 2, 3 or 4 part of a building.
4. Upgrade to meet new classification: Where the changed classification increases risk or changes performance requirements, building elements must be upgraded to meet the specific NCC provisions for that classification (fire separation, means of egress, exit widths, travel distances, access for people with disability, sanitary facilities, structural loading as relevant). Exact provisions depend on classification and element - see below for common examples and references.

Common specific measure examples (apply conditionally depending on classification and building particulars)

1. Travel distance to an exit: For many Class 2-9 occupancies, maximum travel distances are set in NCC Volume One e.g., typically 20 m to an exit in a sprinklered building for some low-risk spaces and 10-15 m for higher-risk spaces - check the applicable clause and tables for the new classification (see NCC Volume One egress requirements and relevant tables).
2. Corridor and exit widths: Exit widths and corridor widths are prescribed in NCC Volume One. For example, carriageway factors and required widths are given in the egress clauses and tables; designers must calculate required widths in mm based on occupant load and discharge capacity (refer to NCC Volume One egress tables and clauses).
3. Fire compartmentation and FRLs: Walls and floor/ceiling assemblies must meet the fire-resistance levels (FRLs) required for the building class and location. For example, internal fire-isolating construction may require 60/60/60 or 90/90/90 FRL depending on separation function and building class - see NCC Volume One, tables for FRLs such as Table S5C21e / S5C21g (refer to the specific table applicable to construction type and location).
4. Sprinklers: A change to a higher-risk classification may trigger a requirement for an automatic fire sprinkler system - check NCC Volume One provisions and relevant state schedules for sprinkler triggers (for example, some Class 2-9 upgrades or changes in effective height may require sprinklers).
5. Accessibility (DDA/NCC access provisions): Where a change introduces a public or occupiable space, access requirements apply (ramp gradients, door widths, sanitary facility numbers). For example, accessible toilet provision and door clearances are specified in NCC Volume One and Volume Two (see relevant clauses such as D3 and D4 in Volume One for access and sanitary facilities).
6. Structural loading: A use that increases imposed loads (e.g., conversion of storage to assembly or retail) will require verification to relevant Australian Standards such as AS 1170.0 and AS 1170.1 for actions and AS 4100 for steel design or AS 1684 for timber framing where applicable.
7. Plumbing and sanitary fixture counts: Changes in classification often change required numbers and types of sanitary fixtures; refer to NCC Volume Three (Plumbing Code of Australia) and Volume One clauses on sanitary facilities for specific counts per occupant.

Key normative references to cite when assessing changes

1. NCC 2022 Volume One - Building Code of Australia (Part A6, egress and fire sections, S5 tables for FRLs, Part D accessibility)
2. NCC 2022 Volume Two - Building Code of Australia (classification rules and Volume Two specific provisions for Class 1 and 10)
3. NCC 2022 Volume Three - Plumbing Code of Australia (sanitary and plumbing requirements)
4. Australian Standards where relevant: AS 1684 (timber framing), AS 4100 (steel structures), AS 3700 (masonry structures), AS 1170 series (structural actions and loads), and accessibility standards referenced in the NCC.

Residential vs Commercial

1. Residential (Class 1 and Class 10): Changes within Class 1/10 domestic uses are generally governed by NCC Volume Two and often involve fewer onerous egress and fire compartmentation upgrades. Small internal changes that remain within Class 1/10 and are minor in area may be exempt under the 10% rule. However, if a residential building is converted to a different classification (for example, a house to a boarding house or short-term accommodation that becomes Class 3 or 1b), the building must be assessed against NCC Volume One requirements for the new class, including fire safety provisions, means of egress, and accessibility where the new use includes public access.
2. Commercial (Class 2-9): Changes that move into or between Class 2-9 occupancies commonly trigger more substantial upgrades. Commercial occupancies tend to have stricter fire separation, FRL, sprinkler, egress, occupant load, and accessibility requirements. For example, converting storage or light industrial space (Class 7b/8) to retail (Class 6) or assembly (Class 9b) will often require improved exit routes, additional sanitary fixtures, possible fire detection and sprinkler systems, and structural checks for increased imposed loads. NCC Volume One is the primary reference for these upgrades.

Exceptions and Exemptions

1. Less than 10% floor area rule: If the new use occupies less than 10% of the floor area of the storey, the predominant classification of the storey may be applied to the whole storey (NCC Volume One and Two, A6G1 Exemptions). This exemption is constrained - it does not apply to laboratories, Class 9b early childhood centres, or Class 2, 3 or 4 parts.
2. More stringent requirement prevails: Where two applicable NCC requirements conflict, the more stringent requirement must be adopted rather than an intermediate compromise (A6 guidance in NCC Volume One/Two).
3. Alternative solutions: Where performance requirements cannot be met using deemed-to-satisfy (DTS) provisions, an alternative solution may be proposed and must demonstrate at least equivalent safety and performance, supported by evidence, testing, or a competent fire engineer/structural engineer report. Alternative solutions must reference NCC Performance Requirements and be accepted by the consent authority or certifier.
4. State schedule exemptions: Some states include specific schedule modifications that may alter triggers for certain upgrades - see next section for state variations.

State and Territory Variations

1. The NCC is a national instrument but each state and territory may adopt schedules to modify or add provisions. When assessing a change of classification, always check the relevant state schedule in NCC 2022 Volume One (Schedules 4-12). Examples to check (but always verify current schedules):
2. Queensland - Schedule 7 may have additional requirements for fire safety systems and local interpretations of sprinkler or smoke hazard management for certain changes of use.
3. New South Wales - State provisions and planning instruments can influence requirements for fire engineering briefs and change-of-use approvals; local councils may require additional documentation.
4. Victoria - While largely aligned with NCC, Victorian building regulations and the VBA can require specific certification steps for occupancy permit changes and may have state-based compliance pathways.

Note: Specific clause numbers and schedule references vary by NCC edition and state. Always consult the current NCC edition and the relevant state schedule in NCC 2022 Volume One (Schedules 4-12) for the exact modifications that apply in the building location.

Practical Compliance Tips

1. Confirm the new classification first: Before design or construction, determine the correct NCC building classification using NCC Volume One/Two Part A6 - this single determination drives most upgrade requirements.
2. Check the 10% rule early: Measure the affected floor area and compare to the storey area to see if the less-than-10% exemption might apply - this can avoid unnecessary upgrades, but confirm exclusions (labs, early childhood, Class 2/3/4 parts).
3. Engage a certifier and specialists early: For changes between commercial classes, involve a registered building surveyor, fire engineer and structural engineer early. Alternative solutions or performance-based designs will likely need specialist reports and evidence.
4. Map elements to NCC clauses: Make a checklist mapping each affected building element (egress, FRL, sprinkler, structural, plumbing, access) to the exact NCC clause or table (for example, cite NCC Volume One S5 tables for FRLs, Part D for access). Include Australian Standard references where relevant (AS 1684, AS 4100, AS 3700, AS 1170 series).
5. Don’t assume grandfathering: Existing construction may be non-conforming to the requirements of a new classification. Where change of use increases risk, expect to upgrade to current NCC requirements unless a specific concession or alternative solution is accepted.
6. Document alternative solutions clearly: If proposing an alternative solution, prepare a clear performance-based justification tied to NCC Performance Requirements, supported by calculations, testing, or engineering reports. Present this to the consent authority with a clear scope of works and conditions.
7. Check state schedules and local planning: Always verify the relevant state schedule in NCC 2022 Volume One (Schedules 4-12) and local council or VBA/DBI requirements early in the project to identify any additional triggers for upgrades (for example, sprinkler or certification thresholds).

References (examples to consult)

1. NCC 2022 Volume One - Building Code of Australia, Part A6 and relevant fire, egress and access sections (see S5 tables, Part D)
2. NCC 2022 Volume Two - Building Code of Australia, Part A6 and Volume Two specific provisions (classification rules)
3. NCC 2022 Volume Three - Plumbing Code of Australia (sanitary and plumbing requirements)
4. Australian Standards referenced above as applicable: AS 1684, AS 4100, AS 3700, AS 1170 series

Note: This article summarises typical NCC requirements and common upgrade triggers for changes of building classification. Some scenarios can be complex or ambiguous; where the NCC or state schedules do not clearly resolve the issue, obtain confirmation from a registered building certifier or an appropriate specialist engineer.