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DBP Act 2020 (NSW): the post-Opal Tower regulation NSW builders work under

NSW Design and Building Practitioners Act 2020: post-Opal Tower duty of care, registration, declared designs, mandatory PI insurance from 1 July 2026 for Class 2/3/9c.

By Dan Waring. Last updated 15 May 2026. Verified 15 May 2026.

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In plain English

The Design and Building Practitioners Act 2020 (NSW) (DBP Act) is the post-Opal Tower, post-Mascot Towers reform of how high-density residential construction is regulated in NSW. It was Parliament’s structural response to the 2018-2019 apartment-building defects crisis. The Act commenced 1 July 2021 and has been phased in since, with a major scope extension and mandatory professional indemnity (PI) insurance regime commencing 1 July 2026 (verified 2026-05-15 against NSW Building Commission notices and multiple insurance-broker confirmations).

The four things it does that matter to a builder:

  1. Statutory duty of care under section 37. Every person who carries out construction work on a building owes a duty of care to current and subsequent owners. The duty applies retrospectively to construction work completed within 10 years before commencement (i.e. from 11 June 2010), giving owners corporations a fresh limitation period to pursue defect claims.
  2. Mandatory registration for design practitioners and building practitioners (and Principal Design Practitioners). Practising on a regulated building without current registration is a regulated offence.
  3. Declared designs regime for Class 2 (apartment) buildings, and from 1 July 2026 also Class 3 (boarding houses, hostels) and Class 9c (residential aged care). A registered design practitioner must lodge a compliance declaration for each declared design (structural, fire safety, waterproofing, building enclosure, mechanical, etc.) before the design is used.
  4. Mandatory PI insurance from 1 July 2026 for registered building practitioners and registered design practitioners on regulated work. Practitioners without compliant PI cannot maintain registration; without registration, they cannot legally do design or D&C work on Class 2/3/9c buildings.

What it requires

For a builder operating in the regulated space:

  1. Register as a building practitioner under Part 4 of the Act before signing a building contract for a Class 2 (or, from 1 July 2026, Class 3 / 9c) building. Registration is by class and by area of specialisation; check the NSW Fair Trading registration portal.
  2. Engage registered design practitioners for every “declared design” component on the project (structural, fire, hydraulics, mechanical, waterproofing, building enclosure, others). Each declared design requires a written compliance declaration from a registered design practitioner before it can be used.
  3. Lodge the compliance declarations before construction work that depends on the design begins. The declaration is the formal practitioner statement that the design complies with the BCA and relevant standards.
  4. Maintain a building manual for the completed work (required under the Act for Class 2 and certain other building classes).
  5. From 1 July 2026, hold PI insurance at a level set by the regulator, with cover that responds to the statutory duty under s.37. PI must cover both design liability (where the builder is doing D&C) and the building practitioner duty. Run-off cover is the necessary follow-on for any practitioner winding down a regulated book.

What it doesn’t cover

  • Class 1a single dwellings (free-standing houses). These remain under the Home Building Act 1989 licensing and insurance regime, not the DBP Act. The crossover point is when a residential project becomes Class 2 (apartments) or moves into Class 3 / 9c.
  • Building technical standards. The BCA / NCC and the relevant AS standards still set the technical content. The DBP Act requires designs to comply with those standards; it does not write the standards.
  • Builder licensing for general residential. The Home Building Act licence (NSW Fair Trading) is the licensing baseline. DBP Act registration is an additional regulated-buildings overlay.
  • Adjudication of payment disputes. Cashflow recovery sits under the Security of Payment Act. The DBP Act provides civil duty-of-care remedies but does not displace SOPA.

Practical implications

  • The 1 July 2026 PI commencement is the single most important date in NSW residential practice in 2026. Builders doing any Class 2 or D&C work that touches design liability need a PI policy in force before the day, with a limit appropriate to the work mix. Brokers should be engaged at least 6 months out; the market has been tightening.
  • Section 37 duty of care reaches backwards. Construction completed since 11 June 2010 is in scope for s.37 claims. Owners corporations across NSW have been refiling defect claims that pre-DBP would have been time-barred or jurisdictionally constrained. Builders with completed Class 2 work in that window should expect claim activity.
  • Declared designs are non-negotiable. A Class 2 project cannot lawfully proceed past the point where a non-declared design would be relied on. The certifier will refuse to issue the Occupation Certificate without the declarations. The lead time to engage a registered design practitioner is real and should be in the programme from CC application.
  • Building manuals require a real document. The manual is not optional metadata; it must be lodged with the OC application. Plan its assembly during the construction phase rather than scrambling at handover.
  • The legislation is under continued review. The NSW Building Commission and NSW Fair Trading have published staged amendments through 2024 and 2025. Always check the current commencement table on NSW Government Building Commission updates before relying on a date.

References

See also

Last updated: 2026-05-15. Verified: 2026-05-15. Quarterly review for currency.

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