Design and Building Practitioners Act 2021: What Apartment Developers Must Know
Author: Franz Phan, Registered Design Practitioner (NSW DBP Act 2020), Director of giantA Pty Ltd — 15+ years experience in NSW multi-residential development
Published: 25 August 2026
If you are developing a Class 2 apartment building in NSW, the Design and Building Practitioners Act 2020 (DBP Act) fundamentally changes who you must hire, what documents you must lodge, and when construction can lawfully begin. Every building element — structure, fire safety, waterproofing, enclosure, and building services — requires a regulated design prepared and declared by a registered design practitioner before a certifier can issue your Construction Certificate. There is no workaround, no exemption for small projects, and no grandfathering for designs prepared before 1 July 2021 that subsequently vary.
Why the DBP Act Exists: From Shergold-Weir to Statutory Duty
The DBP Act is the NSW Government's legislative response to the 2018 Shergold-Weir Building Confidence Report, which found systemic failures in compliance and enforcement across Australia's building industry. The report identified that designs were often not checked against the Building Code of Australia (BCA), that practitioners operated without accountability for design compliance, and that building work frequently deviated from approved plans without oversight.
For apartment developers, the Act introduced a statutory duty of care that did not previously exist. Section 34 of the DBP Act imposes a personal duty on every person who carries out construction work to exercise reasonable care to avoid economic loss caused by defects. This duty cannot be contracted out of, delegated, or insured away — it attaches to the individual practitioner, not just the company entity. The practical consequence is that developers can no longer rely solely on a builder's warranty or professional indemnity insurance to manage defect risk; the design and construction chain now carries individual statutory accountability.
The Act commenced on 1 July 2021, with the Design and Building Practitioners Regulation 2021 providing the operational detail. As of July 2026, the scheme applies to Class 2 buildings (new and existing), Class 3 buildings (new work from 3 July 2023), and Class 9c buildings (new work from 3 July 2023). The planned expansion to remedial work on existing Class 3 and 9c buildings, originally scheduled for 1 July 2026, has been deferred — but developers should monitor Building Commission NSW announcements for the revised commencement date.
The Three Practitioners Every Developer Must Engage
One of the most common questions we receive from developers is: "Who do I actually need to hire?" The DBP Act creates three distinct categories of registered practitioners, each with a specific role in the compliance chain. Understanding who does what is essential for budgeting, scheduling, and avoiding compliance gaps that can halt construction.
Registered Design Practitioner (RDP)
The RDP prepares regulated designs for building elements and performance solutions, and makes Design Compliance Declarations (DCDs) confirming that the design complies with the BCA. Only the person signing off and declaring the design needs to be registered — a team of drafters can work under a single RDP who takes responsibility for the declaration. Design practitioners are registered in specific classes that limit the scope of work they can declare:
- Architectural (unrestricted): All building types, all heights
- Architectural (low-rise): Class 2, 3, or 9c buildings up to 2,000m² gross floor area, excluding Type A or Type B construction
- Architectural (medium-rise): Class 2, 3, or 9c buildings up to 3 storeys (or 4 storeys where the ground level is a Class 7a carpark)
- Engineering (structural): Structural designs for building elements
- Engineering (fire safety): Fire safety system designs and performance solutions
- Engineering (mechanical/electrical/plumbing): Building services designs required by the BCA
Principal Design Practitioner (PDP)
The PDP is an optional but recommended role for larger, more complex projects where hundreds of regulated designs must be coordinated. The PDP collects and reviews design compliance declarations from all RDPs on the project, ensures integration between disciplines, and lodges the complete package on the NSW Planning Portal on behalf of the building practitioner. On a typical 20-unit apartment project, we would expect 40–60 individual regulated designs across architectural, structural, fire, hydraulic, and mechanical disciplines — the PDP role becomes essential at this scale.
Registered Building Practitioner (RBP)
The RBP is the builder or head contractor who carries out or supervises the building work. The RBP lodges regulated designs and declarations on the Planning Portal, manages any design variations during construction, and makes the Building Compliance Declaration at completion — confirming that the as-built work complies with the declared designs and the BCA. A developer cannot obtain an Occupation Certificate without the RBP's Building Compliance Declaration being lodged.
What Counts as a Regulated Design?
Not every drawing on a Class 2 project is a regulated design. The DBP Regulation defines regulated designs narrowly — they cover only designs related to a building element or a performance solution. Building elements are:
1. Fire safety systems (including passive fire separation)
2. Waterproofing
3. Building structure (foundations, floors, walls, roofs, columns, beams)
4. Building enclosure (facade, cladding, weatherproofing)
5. Building services required by the BCA (mechanical, plumbing, electrical, fire)
6. Vertical transportation aspects required for BCA compliance
This means that a typical apartment project requires regulated designs for the structural frame, fire separation walls, waterproofing membranes, facade system, mechanical ventilation, hydraulic services, and any performance solutions (such as an alternative solution to the Deemed-to-Satisfy provisions). Interior fit-out drawings, joinery details, and finishes schedules are generally not regulated designs unless they involve a building element.
What is excluded?
Some building work is excluded from requiring compliance declarations under Section 13 of the DBP Regulation. Key exclusions include work valued under $5,000 (including labour and materials), work exempt under environmental planning (except waterproofing), maintenance of building components (excluding load-bearing elements), and non-structural fit-out for Class 5, 6, 9a, or 9b parts of a mixed-use building. Developers should not assume these exclusions apply broadly — they are narrow and specific.
The Developer's Compliance Workflow: Step by Step
From a developer's perspective, the DBP Act adds a structured documentation phase between design completion and construction commencement. The following table maps the key milestones and who is responsible at each stage.
| Stage | Action | Responsible Practitioner | Timing |
|---|---|---|---|
| 1. Design development | Prepare regulated designs for all building elements | RDP (each discipline) | During DA/CC design phase |
| 2. Design declaration | Make Design Compliance Declaration for each regulated design | RDP | Before CC/CDC issuance |
| 3. Portal lodgement | Lodge regulated designs and DCDs on NSW Planning Portal | RBP or PDP | Before construction starts |
| 4. Certifier verification | Certifier checks declared designs before issuing CC/CDC | Registered Certifier | Prior to CC/CDC issue |
| 5. Construction | Build in accordance with declared designs | RBP | During construction |
| 6. Variation management | Prepare new regulated design and DCD for any variation involving a building element | RDP (if variation) | Before varied work continues |
| 7. Building declaration | Make Building Compliance Declaration at completion | RBP | Before Occupation Certificate |
| 8. Occupation | Certifier issues Occupation Certificate | Registered Certifier | After BCD lodged |
The critical point for developers is Step 3: construction cannot lawfully commence until all regulated designs and DCDs are lodged on the Planning Portal and the certifier has verified them. This adds approximately 2–4 weeks to the pre-construction timeline compared to the pre-2021 process, depending on project complexity and how well the design documentation is coordinated.
Cost Implications: What the DBP Act Adds to Your Development Budget
The DBP Act introduces direct and indirect costs that developers must factor into their feasibility studies. Based on our project experience across Sydney, the following table summarises the additional compliance costs for a typical Class 2 apartment development.
| Cost Item | Small Project (6–12 units) | Medium Project (20–40 units) | Large Project (50+ units) |
|---|---|---|---|
| RDP fees (architectural) | $8,000–$15,000 | $18,000–$35,000 | $40,000–$80,000 |
| RDP fees (engineering) | $5,000–$10,000 | $12,000–$25,000 | $25,000–$50,000 |
| PDP coordination fee | $2,000–$4,000 | $5,000–$12,000 | $15,000–$30,000 |
| Design Compliance Declarations | $500–$1,000 per DCD | $500–$1,000 per DCD (x40–60) | $500–$1,000 per DCD (x100+) |
| Portal administration | $1,000–$2,000 | $2,000–$5,000 | $5,000–$15,000 |
| Total estimated additional cost | $18,000–$35,000 | $45,000–$95,000 | $120,000–$250,000 |
These costs are in addition to standard design and documentation fees. They represent the compliance overhead of the DBP Act — the price of having regulated designs prepared, declared, and lodged by registered practitioners. For developers running tight feasibility margins, this can represent 1–3% of total construction cost on smaller projects, decreasing to 0.5–1% on larger projects where the compliance cost is spread across more units.
Real Project Experience: Compliance in Practice
Project A — 12-unit apartment building, Merrylands
A developer approached us in early 2025 with Development Consent for a 12-unit, three-storey Class 2 building in Merrylands. The original design had been prepared by an unregistered draftsman and predated the DBP Act requirements. To proceed to a Construction Certificate, we needed to prepare regulated designs for the structural frame (engineer), fire separation (architectural + fire engineer), waterproofing (architectural), and building enclosure (architectural). The compliance documentation phase took three weeks, adding approximately $22,000 in RDP and declaration fees to the project budget. The certifier issued the Construction Certificate within five business days of receiving the lodged declarations — a smooth outcome because the designs were coordinated and complete on first submission.
Project B — 24-unit apartment building, Campsie
A larger project in Campsie required 47 individual regulated designs across five disciplines. We were engaged as Principal Design Practitioner to coordinate the engineering, fire safety, hydraulic, mechanical, and architectural declarations. The coordination challenge was integration: the fire engineer's performance solution for the corridor smoke hazard management required specific architectural details in the separation walls, which in turn affected the structural engineer's load calculations. By appointing a PDP early, we resolved these interdisciplinary conflicts during the design phase rather than during construction, where variations would have cost significantly more. The total compliance overhead was approximately $68,000, representing 0.8% of the $8.5 million construction budget.
Project C — 6-unit boutique development, Randwick
A smaller boutique development demonstrated that the DBP Act's compliance costs are proportionally higher for small projects. The six-unit Randwick project required 18 regulated designs, and the compliance overhead of $19,500 represented 2.1% of the $930,000 construction budget. The developer had not budgeted for DBP Act compliance and had to restructure their financing. This is a common scenario — many small-scale developers are still unaware of the full cost implications of the regulatory framework.
Common Pitfalls for Developers
From our experience working on Class 2 projects across Sydney, the following issues recur frequently and can cause significant delays and cost overruns.
Engaging unregistered designers. Developers sometimes engage a drafting service or building designer who is not registered under the DBP Act to prepare initial designs, intending to have a registered practitioner "sign off" later. This approach often fails because the registered practitioner must take responsibility for the design's BCA compliance — they cannot simply rubber-stamp someone else's work without reviewing and potentially reworking it. The more efficient approach is to engage the RDP from the outset.
Underestimating the number of regulated designs. Developers frequently assume that a single architectural package covers all building elements. In practice, each building element requires a separate regulated design and DCD from the appropriately registered practitioner. A typical 20-unit project generates 40–60 separate declarations.
Failing to plan for variations. During construction, variations involving building elements are inevitable. Each variation requires a new regulated design and DCD before the varied work can continue. Developers who do not budget for variation compliance costs can face unexpected expenses mid-construction.
Misunderstanding the mixed-use rule. If a building has a Class 2 component (e.g., residential apartments above ground-floor retail), the DBP Act obligations apply to the entire building, not just the residential floors. This catches developers of mixed-use projects by surprise.
The Building (Approvals and Practitioners) Bill 2026: What's Changing
On 6 May 2026, the NSW Government passed the Building (Approvals and Practitioners) Bill 2026, which represents the most significant overhaul of NSW building law since the DBP Act itself. While the DBP Act's core compliance declaration scheme remains, the Bill introduces several changes that affect apartment developers:
- Building approvals replace Construction Certificates. The new Act introduces a "building approval" that integrates design compliance declarations into the approval itself, reducing documentation duplication.
- Staged approvals formalised. Developers can now seek staged building approvals for different construction phases, providing greater flexibility for complex projects.
- Prefabricated buildings recognised. Modular and prefab construction is formally recognised, with manufacturers required to provide prefabricated building declarations confirming BCA compliance.
- Decennial liability insurance (DLI). A new 10-year defect insurance requirement is being introduced for apartment buildings over three storeys, covering critical building elements. The DLI scheme is being developed in parallel with the Building Bill reforms.
Developers should note that the transition from the current EP&A Act approval framework to the new Building Bill framework will occur progressively. The DBP Act compliance declaration scheme continues to operate throughout the transition. We recommend engaging early with your design practitioner to understand how the new framework will affect your project timeline.
Stakeholder-Specific Guidance
For Developers
Budget 1–3% of construction cost for DBP Act compliance overhead. Engage a Principal Design Practitioner on projects with 15+ units to manage interdisciplinary coordination. Factor 2–4 additional weeks into your pre-construction timeline for design declarations and portal lodgement. Ensure your building contract includes provisions for variation compliance costs.
For Builders
Register as a Building Practitioner with NSW Fair Trading before tendering for Class 2 projects. Understand your obligation to lodge regulated designs before construction starts. Implement a variation management protocol that triggers the regulated design process automatically for any change involving a building element. Your Building Compliance Declaration at completion must be supported by as-built documentation — maintain construction records from day one.
For Strata Managers and Owners
The DBP Act applies to existing Class 2 buildings, not just new construction. Any remedial building work involving a building element — such as rectifying waterproofing defects, replacing cladding, or repairing structural elements — requires regulated designs and compliance declarations. Strata committees commissioning remedial work must engage registered practitioners, and the building practitioner must lodge declarations on the Planning Portal before remedial work commences.
Frequently Asked Questions
Does the DBP Act apply to all apartment buildings?
Yes. The DBP Act applies to all Class 2 buildings in NSW — new construction, alterations and additions to existing buildings, and remedial work involving building elements. There is no minimum size threshold, and the Act applies to mixed-use buildings in their entirety where any part is Class 2. Work valued under $5,000 is excluded, but this threshold rarely applies to apartment development work.
Can I use a building designer instead of a registered design practitioner?
You can engage anyone to develop initial design concepts, but only a registered design practitioner can make the Design Compliance Declaration required for regulated designs. In practice, engaging an unregistered designer for initial work and then having a registered practitioner review and declare the design often costs more than engaging the registered practitioner from the start, because the RDP must thoroughly review and take responsibility for the design's BCA compliance.
How long does the compliance declaration process add to a project?
For a typical 12–24 unit apartment project, the compliance declaration phase adds 2–4 weeks to the pre-construction timeline. This includes preparing and declaring all regulated designs, lodging them on the Planning Portal, and the certifier verifying the declarations before issuing the Construction Certificate. Complex projects with performance solutions may take longer. Engaging a Principal Design Practitioner can reduce this timeframe through better coordination.
What happens if construction starts without lodged regulated designs?
Starting building work without lodged regulated designs and Design Compliance Declarations is a breach of the DBP Act. The Building Commissioner can issue stop-work orders and building work rectification orders. The certifier cannot issue an Occupation Certificate without the Building Compliance Declaration, which cannot be made without the underlying design declarations. Penalties for non-compliance include fines up to $165,000 for a body corporate and $55,000 for an individual, plus potential disciplinary action against registered practitioners.
How does the DBP Act interact with BASIX and NatHERS?
BASIX and NatHERS compliance is separate from the DBP Act regulated design scheme, but they intersect. Energy efficiency and thermal performance designs may constitute building services designs required by the BCA, triggering the need for a regulated design and DCD from an appropriately registered mechanical or electrical engineering practitioner. Developers should ensure that their BASIX certification and NatHERS assessment are coordinated with the regulated design schedule to avoid gaps.
Will the Building Bill 2026 replace the DBP Act?
No. The Building (Approvals and Practitioners) Bill 2026 builds on the DBP Act's framework rather than replacing it. The compliance declaration scheme remains, but is integrated into the new building approval process. The key change for developers is that design compliance declarations will be embedded in the building approval itself, reducing the current duplication between the CC process and the DBP Act lodgement process. The transition will occur progressively through 2026–2027.
Do I need a Principal Design Practitioner?
A PDP is not mandatory, but is strongly recommended for projects with 15 or more units, or any project involving performance solutions across multiple disciplines. The PDP coordinates design compliance declarations across all RDPs, resolves interdisciplinary conflicts, and manages portal lodgement. Without a PDP, the building practitioner must coordinate declarations directly — a role that builders are typically not equipped to perform efficiently.
What are the insurance implications for developers?
The DBP Act introduces a statutory duty of care that cannot be contracted out of. Developers should ensure their design and building contracts include appropriate warranties and indemnities, and that all engaged practitioners hold current professional indemnity insurance. The forthcoming decennial liability insurance (DLI) scheme for buildings over three storeys will add a further insurance cost that should be factored into feasibility studies for larger apartment projects.
References
1. NSW Government — Design practitioner obligations when working on regulated buildings: https://www.nsw.gov.au/housing-and-construction/compliance-and-regulation/professionals-working-on-regulated-buildings/design-and-building-practitioners/design-obligations
2. Design and Building Practitioners Act 2020 (NSW): https://www.legislation.nsw.gov.au/view/html/inforce/current/act-2020-007
3. Design and Building Practitioners Regulation 2021 (NSW): https://legislation.nsw.gov.au/view/html/inforce/current/sl-2021-0152
4. NSW Government — Changes in the residential building industry (Building Commission NSW): https://www.nsw.gov.au/departments-and-agencies/building-commission/industry-changes
5. Shergold Weir Building Confidence Report (2018): Building Ministers' Forum
6. NSW Planning Portal — Developer and Practitioner Resources: https://www.planningportal.nsw.gov.au
About the author: Franz Phan is a Registered Design Practitioner under the NSW Design and Building Practitioners Act 2020 and Director of giantA Pty Ltd, a Sydney-based design and building consultancy specialising in multi-residential and commercial projects. giantA is registered with NSW Fair Trading to prepare and declare regulated designs for Class 2 buildings across all architectural registration classes.
For a consultation on your Class 2 apartment development, contact giantA at he@gianta.com.au or visit https://www.gianta.com.au.