What a Class 2 building practitioner is in NSW, who needs one, and how to verify registration in two minutes. A plain-English guide for strata committees and owners.
Your engineer's report lands, and buried in it is a line saying the works must be carried out by a "Class 2 registered building practitioner." Nobody on the committee has heard the term before, and none of the three quotes already on the table mention it. Here is what it actually means, why it decides who is legally allowed to touch your building, and how to check a contractor's registration in about two minutes.
A Class 2 building practitioner is a builder registered under the Design and Building Practitioners Act 2020 (the DBP Act) to carry out or oversee building work on a Class 2 building. Strictly speaking there is no registration category with that name — the legal term is building practitioner, and "Class 2" describes your building, not the person. In practice the industry uses the two together, and engineers write it into reports because it is shorthand for "a builder who is legally allowed to do this job."
The distinction matters more than it sounds. When a contractor tells you they are "Class 2 registered," what you need to confirm is that they hold a current building practitioner registration under the DBP Act, in a class that covers your building. Plenty of good builders hold a NSW contractor licence and nothing else — and on a Class 2 job, that is not enough.
Class 2 is a National Construction Code classification. It covers buildings containing two or more sole-occupancy units that are separate dwellings — in plain terms, apartment and unit blocks. Almost every residential strata scheme in Sydney above a duplex is Class 2, and so is the residential portion of a mixed-use building with shops or offices below.
The DBP scheme also regulates certain Class 3 buildings (boarding houses, hostels, student accommodation, hotels and motels) and Class 9c buildings (residential aged care). If your building has a Class 2 part, the scheme applies to that part even if the rest of the building is something else.
Why the classification matters: the DBP Act only regulates work on these building classes. A defect on a Class 2 apartment block is regulated work. The same defect on a standalone house is not.
Building Commission NSW registers building practitioners in several classes, and the class determines what a contractor may legally declare and lodge. The three you will meet on a strata remedial job are:
| Registration class | What it authorises |
| Building practitioner – general | Class 2, 3 and 9c building work with no height or floor-area restriction. Covers everything the low-rise and medium-rise classes cover. |
| Building practitioner – general (medium-rise) | Limited to a maximum of 3 storeys, or 4 storeys where the ground or first storey is a Class 7a carpark. Excludes Type A construction. |
| Building practitioner – general (low-rise) | Limited to a maximum gross floor area of 2,000 m², and excludes Type A and Type B construction. |
Most remedial contractors trade as companies, which adds a second layer. A company must hold building practitioner – body corporate registration, and it must nominate an individual who holds registration as a body corporate nominee or as a general building practitioner. If that nominated individual holds only a low-rise or medium-rise registration, the company is restricted to the same class.
This is the trap on a taller building. A contractor can be genuinely, currently registered — and still not authorised to declare the work on your eight-storey block. Check the class, not just the tick.
No, and this is the most common misunderstanding on strata tenders. A contractor licence is issued under the Home Building Act 1989 and lets someone contract to do residential building work. DBP registration is issued under the DBP Act and lets someone perform and declare regulated work on a Class 2, 3 or 9c building.
You need a contractor who holds both. Building Commission NSW is explicit on the point: a builder must register as a building practitioner to oversee work on a Class 2 building even if they already hold a valid NSW building licence.
So when a quote arrives with a licence number on the letterhead, that number tells you nothing about DBP registration. Different registers, different numbers, different tests. Ask for both.
Since 1 July 2021, remedial building work on Class 2 buildings has been regulated under the DBP Act. That covers repair, alteration and renovation work on an existing building, and defect rectification — the everyday substance of strata capital works. Concrete repairs, structural strengthening, facade remediation, balcony rectification and most waterproofing all sit inside it.
Two things sit outside. Some remedial work is exempt development under the State Environmental Planning Policy and is excluded from the scheme. And emergency remedial building work can proceed without regulated designs lodged first — but only where it meets four specific criteria, and the practitioner must still make a building compliance declaration afterwards. A roof membrane at end of life, with minor leakage and no safety risk, is not an emergency; Building Commission NSW uses almost exactly that scenario as its worked example of work that must go through the full process.
Waterproofing deserves its own note, because it is where committees most often get bad advice. Waterproofing is only excluded from the scheme if it meets every one of three conditions under clause 13 of the DBP Regulation: it results from alterations to a bathroom, kitchen, laundry or toilet; it relates to a single dwelling; and it is exempt development. Common-property balcony or roof waterproofing across multiple lots meets none of that. It is regulated work.
For Class 3 and 9c buildings the position changed in 2026. Extending the DBP Act to remedial work on those classes was deferred to 1 July 2028. Class 2 was never affected by that deferral — it has been regulated since 2021 and remains so today.
Registration is not a badge. It carries a specific set of obligations, and those obligations are what produce the paper trail your owners corporation will rely on if a defect appears in five years.
Before work starts, a registered design practitioner must prepare a Construction Issued Regulated Design (CIRD) — drawings, specifications, a schedule of materials, and clear demarcation between the existing building and the new remedial work. The registered building practitioner must then lodge those designs and the accompanying design compliance declarations on the NSW Planning Portal before any of the related building work begins.
During the job, variations that touch a building element or a performance solution require a new or updated regulated design and a fresh declaration, lodged within one day of the varied work starting. If a variation is significant enough, work stops until the design catches up. It is an offence under the DBP legislation for related building work to be performed without being reflected in the CIRD.
At the end, the building practitioner lodges a building compliance declaration stating the work was built in accordance with the declared designs and otherwise complies with the Building Code of Australia. That declaration cannot be delegated to anyone else — not the project manager, not the site supervisor, not the engineer. Only the registered building practitioner can make it.
For a committee, the practical read is simple: if your contractor cannot explain this sequence back to you, they have not done it before.
Do this before you sign anything, and do it yourself rather than accepting a screenshot.
Two minutes of this beats any amount of assurance in a tender document. It also separates the field quickly — for the wider set of questions worth asking, see our guide on how strata managers should choose a remedial builder.
Building Commission NSW has legislative power to audit remedial projects, and authorised officers focus specifically on whether the practitioners are registered and whether the CIRDs contain enough detail to produce compliant work. Where work is found to be non-compliant, the Commission can issue formal warnings, a Building Work Rectification Order, a Stop Work Order or a Prohibition Order, and impose financial penalties.
The consequences that land on the owners corporation are usually more mundane and more expensive: a stop-work order halfway through a scaffolded facade program, a rectification order requiring work to be redone, an insurer asking questions, or a purchaser's solicitor finding no Planning Portal record during a sale. None of that is easily recoverable from a contractor who has moved on.
The upside sits in the same Act. Section 37 imposes a statutory duty of care on anyone carrying out construction work to exercise reasonable care to avoid economic loss caused by defects — and that duty is owed to the owner of the land and to each subsequent owner, which includes owners corporations. It cannot be contracted out of or delegated. Using registered practitioners and keeping the lodgement records is what makes that protection usable rather than theoretical. We have set out how the wider framework works for committees in our plain-English guide to the DBP Act.
No. The official category is "building practitioner," registered under the DBP Act 2020. "Class 2" refers to the building classification under the National Construction Code, not to a class of registration. The two are used together in industry because building practitioner registration is what authorises work on Class 2 buildings.
It depends on whether the work is regulated. Remedial work on a Class 2 building is regulated under the DBP Act unless it is excluded as exempt development or qualifies as emergency remedial building work. Most common-property concrete, structural, facade and waterproofing work is regulated, regardless of value.
No. Building Commission NSW states that registration as a building practitioner is required to oversee building work on a Class 2 building even where the contractor holds a valid NSW building licence under the Home Building Act 1989. Both are needed.
Search the NSW public register at verify.licence.nsw.gov.au by registration number or exact company name. Confirm the status is current, that the class is a building practitioner class, that it covers your building's height and construction type, and that the registered entity matches the contracting entity.
The registered building practitioner. They lodge the regulated designs and design compliance declarations before work starts, and the building compliance declaration at the end. The final building compliance declaration cannot be delegated. Your owners corporation should ask for the lodgement reference and keep it on file.
Ask each contractor for their DBP registration number, verify it yourself, and confirm the class covers your building. Then ask who is preparing the Construction Issued Regulated Design and who is lodging on the Planning Portal. If those two questions produce a vague answer, that is your answer.
Atomic Projects is a DBP-registered building practitioner delivering remedial building works for Sydney strata and commercial buildings — concrete and structural repair, facade remediation, waterproofing and defect rectification — with registered designs and Planning Portal lodgements handled as part of the job. See how we work as your Class 2 building practitioner, or book a free assessment and we will tell your committee what the work involves and what it should cost.
Send photos, the engineer's report, or just the symptoms — whatever you've got. A registered builder reads it and calls you back. No call centre, no obligation.