Answer first: Yes. Under clause 12 of the DBP Regulation 2021, if any part of a NSW building is Class 2, the whole building is regulated — including its shop (Class 6), office (Class 5) and carpark (Class 7a) parts. Registered design practitioners must prepare regulated designs and declarations for every part, lodged on the NSW Planning Portal before work starts.
By: giantA Pty Ltd · Updated 14 October 2026
What makes a mixed-use building “regulated” under the DBP Act?
The Design and Building Practitioners Act 2020 (DBP Act) applies to “building work” — construction, alterations or additions, and repair, renovation or protective treatment — on a building of a class or type prescribed by the regulations. Clause 12 of the Design and Building Practitioners Regulation 2021 then prescribes a building if the building, or a part of the building, is:
- a Class 2 building, or
- a Class 3 building, other than temporary accommodation facilities, or
- a Class 9c building.
The Regulation spells out the consequence with its own example: the Act and Regulation apply to a mixed-use building comprising Class 2, Class 5 and Class 6 buildings, including the building’s Class 5 and Class 6 parts. In plain terms, the apartments do not just bring themselves into the scheme — they bring the ground-floor shops, the commercial levels and the podium with them.
NSW guidance on design practitioner obligations agrees: regulated designs are required for all parts of a building with a regulated part — for example, offices (Class 5) with residences (Class 2), or work above a Class 7 carpark.
How does the NCC classify each part of a mixed-use building?
The Building Code of Australia (BCA, Volume One of the National Construction Code) classifies buildings by use, and every part of a building must be separately classified. The ABCB’s building classifications guidance uses exactly the shop-top and podium form Sydney developers build: a basement carpark (Class 7a), ground-floor retail (Class 6), residential apartments (Class 2) and offices above (Class 5).
There is a concession in NCC Part A6 that lets a minor use of 10% or less of a storey’s floor area adopt the classification of the rest of that storey. It does not help here: the limitation excludes Class 2, 3 or 4 parts, so a residential sole-occupancy unit cannot be “absorbed” into a shop or office classification. In NSW, the edition in force is NCC 2022 Amendment 2 (from 29 July 2025); NSW will adopt NCC 2025 on 1 May 2027.
| Part of the building | Typical NCC class | Typical use | Inside the DBP scheme when a Class 2 part exists? |
|---|---|---|---|
| Apartments | Class 2 | Two or more sole-occupancy units (dwellings) | Yes — this is the trigger |
| Ground-floor shops, cafés, restaurants | Class 6 | Retail goods or services direct to the public | Yes — Regulation cl 12 example |
| Commercial or professional suites | Class 5 | Offices for professional or commercial purposes | Yes — Regulation cl 12 example |
| Basement or podium carpark | Class 7a | Carpark | Yes — NSW guidance refers to work above a Class 7 carpark; designs required for all parts |
| Single caretaker or shop-top dwelling (no other dwellings) | Class 4 part | The only dwelling in a Class 5–9 building | Not listed in cl 12 — confirm classification first (see below) |
Is a single flat above a shop a Class 2 building?
Usually not. Under NCC A6G5, a dwelling in a Class 5, 6, 7, 8 or 9 building is Class 4 if it is the only dwelling in the building — the classic flat above a shop. A building can only contain one Class 4 dwelling. Once there are two or more dwellings attached to another class, they become Class 2 (or possibly Class 3), and they need not be attached to each other or be more than a single storey (NCC A6G3).
That distinction matters because clause 12 lists Class 2, 3 and 9c — not Class 4. Two practical traps follow:
- Adding a second flat changes everything. The NCC guidance notes that if part of the principal building is converted into an additional flat, both dwellings become classifiable as Class 2. A modest shop-top conversion can therefore move the whole building — shop included — into the DBP scheme.
- Two dwellings over a common carpark are Class 2. Class 2 can be a single-storey attached dwelling with a common space below, such as a shared basement or carpark.
Where classification is unclear, the approval authority decides — so settle it with your certifier at concept stage. Our explainer on what a Class 2 building is covers the residential boundaries in more detail.
Which designs need a registered design practitioner across the non-residential parts?
A regulated design is a design prepared for a building element or a performance solution for building work. For the DBP scheme, building elements are fire safety systems (including passive fire), waterproofing, building structure, building enclosure, BCA-required building services, and the BCA-related aspects of a vertical transportation product. Because the whole building is prescribed, these elements are regulated in the retail, commercial and carpark zones too — not only inside the apartments.
| Building element | Where it shows up in a mixed-use building | Registration class that typically declares it |
|---|---|---|
| Structure | Transfer slabs and beams over retail or carpark grids, basement walls, podium slabs | Design practitioner — structural engineering (geotechnical for shoring, underpinning and anchoring) |
| Fire safety (active and passive) | Fire separation between classes, egress shared by residents and shoppers, sprinklers, hydrants, smoke control in the carpark | Fire safety engineering; relevant fire systems classes |
| Waterproofing | Podium and communal terraces over shops or carparks, planter boxes, wet areas | Architectural or building design classes (within registration limits) |
| Building enclosure | Shopfront glazing, façade across commercial and residential levels | Architectural / building design; façade class where engaged |
| BCA-required services | Carpark ventilation, mechanical exhaust from food tenancies, stair pressurisation | Mechanical, electrical, drainage classes |
Each regulated design must, as far as reasonably practicable, integrate other regulated designs — on mixed-use jobs, think café exhaust routes crossing residential fire compartments, or podium waterproofing that ignores carpark drainage. Our guide to Class 2 regulated designs and building elements goes deeper on each element.
Are shop and office fit-outs excluded from the scheme?
Some are. Clause 13 of the Regulation excludes certain work from being “building work”, including fit-out of part of a building — but only if all three conditions are met:
- the part is a Class 5, 6, 9a or 9b part, or will become one through a change of building use connected with the work;
- the work is the subject of a development consent that primarily relates to the fit-out; and
- the exclusion applies only to the extent the work does not relate to a structural component of the building.
NSW guidance describes a structural component as an internal or external load-bearing component essential to the stability of the building or part of it — including foundations and footings, floors, walls, roofs, columns and beams. So a later tenancy fit-out of a ground-floor shop under its own fit-out consent can sit outside the scheme, but any new slab penetration, removed load-bearing wall or new stair opening in that tenancy is back inside it. In our reading, where shell-and-core and first fit-out are delivered under the base-building consent, the “primarily relates to the fit-out” condition is unlikely to be satisfied — confirm the position with your certifier.
Who lodges what on the NSW Planning Portal for a mixed-use project?
The lodgement sequence is the same as any Class 2 job, but the document set covers every part of the building. Under the Planning Portal developer and practitioner workflow:
- Developer creates the building work case and uploads regulated designs and declarations, which are shared with the certifier on the construction certificate (CC) application.
- Design practitioners make a design compliance declaration for each construction-issued regulated design — a separate declaration for each design, even if one practitioner holds several classes.
- Certifier cannot issue a CC or complying development certificate without the declared designs it requires.
- Building practitioner (or an appropriate practitioner on their behalf) lodges the complete set for each CC before work starts; if a principal design practitioner is appointed, they get 14 days’ written notice before work starts.
- Variations to a building element or performance solution need new declared designs, lodged within one day of the variation.
- Before the occupation certificate (OC), the building practitioner lodges the building compliance declaration, as-built designs, variation statements and the contractor document. Only the building practitioner can make that declaration.
There is only ever one building practitioner for a project. For staging, sequencing and timing detail, see our guides to Class 2 construction certificates, Class 2 occupation certificates and RDP, building practitioner and PDP roles.
Do low-rise and medium-rise registrations cover shop-top and podium buildings?
Only within their limits, and mixed-use buildings test those limits quickly. NSW Government’s building classes and roles page sets the conditions:
| Registration condition | Official limit | What it means for mixed-use |
|---|---|---|
| Low-rise | Class 2, 3 or 9c building (or building with such a part) with a maximum gross floor area of no more than 2,000 m², excluding Type A or Type B construction | Small shop-top buildings only; the floor area of the shops and offices sits inside the same building |
| Medium-rise | Maximum 3 storeys, or 4 storeys where the ground level or first storey is a Class 7a carpark; excludes Type A construction in relation to Class 4, 5, 6, 7b and 8 buildings | A podium carpark can earn one extra storey; retail or commercial parts in Type A construction take the building outside this condition |
| Unrestricted classes | No size limit within the practitioner’s field | Needed once the building exceeds the low-rise or medium-rise limits |
A company is restricted to the same condition as its nominated building practitioner. Building design (low-rise and medium-rise) classes cannot declare an architectural service, engineering or fire systems, and the “building design” class covers Class 3 and 9c only — not Class 2. Check every consultant’s class and condition on the NSW DBP register against the whole building, not just the residential floors. Our comparison of a registered design practitioner vs an architect explains how the classes differ.
How do Class 3 and 9c mixed-use timings compare?
Class 2 rules apply to new and existing buildings now. Class 3 and 9c arrived later and in stages:
- new Class 3 and 9c buildings, and buildings with a Class 3 or 9c part, from 3 July 2023;
- alteration, repair or renovation work on existing Class 3 and 9c buildings from 1 July 2028;
- from 1 July 2024, certain new hotels, motels and minor accommodation parts are exempt — but hotels and motels only if no part is subject to a strata scheme or contains serviced apartments.
Be careful applying those dates to a building that also has apartments. The Regulation frames its Class 3 and 9c carve-outs around a “designated class 3 or 9c building”, defined as one where no part of the building is a Class 2 building. If a boarding house, seniors living or hotel component shares a building with Class 2 apartments, plan on the Class 2 rules governing the whole project, and confirm with your certifier before relying on any Class 3 or 9c transition.
What does this mean for work on existing mixed-use buildings?
Because Class 2 coverage extends to existing buildings, work in the non-residential parts of an established mixed-use strata building — a new shopfront, structural changes in a tenancy, carpark waterproofing or fire upgrades — can be regulated building work needing declared designs before it starts, unless an exclusion applies. Owners corporations planning defect rectification should read our Class 2 remedial building work guide; lot owners can see our Class 2 apartment renovations guide.
What should developers check before briefing consultants?
- Confirm the classification of every part with your certifier — including whether a single dwelling is a Class 4 part or the scheme is triggered by a second dwelling.
- Assume all parts are in scope once a Class 2 part exists, and scope regulated designs for retail, commercial and carpark elements.
- Check each consultant’s DBP class and any low-rise or medium-rise condition against the whole building’s floor area, storeys and construction type.
- Separate base-building and tenancy fit-out consents where that is genuinely the plan, and keep structural work out of fit-out scopes.
- Set up the Planning Portal building work case so declarations for every part are lodged as a complete set for each CC.
Frequently asked questions
Does one apartment above my shop trigger the DBP Act?
Usually not on its own. A single dwelling in a Class 5–9 building is generally a Class 4 part, which is not listed in clause 12. Add a second dwelling and both become Class 2, bringing the whole building into the scheme. Confirm the classification with your certifier.
Do ground-floor shops in an apartment building need regulated designs?
Yes, where the work involves a building element or performance solution. The Regulation’s own example confirms the Act applies to the Class 5 and Class 6 parts of a building with a Class 2 part, unless an exclusion such as the qualifying fit-out exclusion applies.
Is the basement carpark under apartments covered?
Yes. NSW guidance says regulated designs are required for all parts of a building with a regulated part and gives work above a Class 7 carpark as an example. Structure, fire safety, waterproofing and required services in the carpark all need declared designs.
Can a retail tenant fit out a shop without an RDP?
Possibly. Fit-out of a Class 5 or 6 part is excluded where the development consent primarily relates to the fit-out — but only to the extent the work does not involve a structural component. Slab penetrations or load-bearing wall changes are still regulated.
Can a low-rise registered builder deliver a four-storey mixed-use building?
Not under the low-rise condition, which is tied to 2,000 m² gross floor area and excludes Type A and Type B construction. The medium-rise condition allows up to four storeys only where the ground or first storey is a Class 7a carpark, subject to its construction-type limits.
Do the 2028 Class 3 dates help if my building has apartments too?
Do not rely on them. The Regulation’s Class 3 and 9c carve-outs are framed around a building where no part is Class 2. Where apartments are present, plan on Class 2 rules applying to the whole building and confirm with your certifier.
How giantA can help
We design and document mixed-use and shop-top projects across Greater Sydney and help clients scope regulated designs for every part of the building. Our principal building designer is a NSW Registered Design Practitioner (DEP0001351). See our Class 2 building design, Class 6 retail shop design and Class 5 office building design services, or ask giantA via Help.
Preferred sources (verify current versions)
- Design and Building Practitioners Regulation 2021 (cl 12 prescribed buildings; cl 13 excluded work)
- Design and Building Practitioners Act 2020
- NSW Government — Design practitioner obligations when working on regulated buildings
- NSW Government — Building practitioner obligations when working on regulated buildings
- NSW Government — Building classes and roles under the DBP scheme
- NSW Planning Portal — Developer and practitioner resources: I have a DA, CC or CDC approval
- ABCB — Building classifications (mixed-use buildings)
- NCC 2022 — Part A6 Building classification (A6G1, A6G3, A6G5)
- NSW Government — How to comply with the National Construction Code
- NSW Government — DBP practitioner register search