Do You Need a Building Certifier for Renovations, Granny Flats and More?

Not every building project needs a certifier. But most do, and the consequences of getting it wrong are serious: council stop-work orders, fines, and even demolition of unapproved work. This guide covers the most common residential projects and tells you clearly whether you need a certifier for each one.

Do I need a building certifier for a renovation in NSW?

It depends on the scope of work. If your renovation affects the structure, fire safety, waterproofing, or plumbing of the building, you will need either a Construction Certificate (CC) or a Complying Development Certificate (CDC), and a Principal Certifier (PC) must be appointed to conduct mandatory inspections.

Renovations that typically require a certifier:

• Removing or altering load-bearing walls
• Adding a room, level, or extension to an existing building
• Bathroom or laundry renovations that involve waterproofing work
• Converting a garage to a habitable room
• Significant changes to the building’s footprint, layout, or structural elements
• Any work that changes the building’s classification under the National Construction Code (NCC)

Renovations that generally do not require a certifier:

• Painting (internal or external)
• Replacing fixtures and fittings (taps, light switches, door handles)
• Installing new floor coverings over existing floors
• Minor landscaping that does not affect drainage or structures
• Replacing like-for-like materials (e.g. replacing a broken window with the same type and size)

These minor works are generally classified as “exempt development” under the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008 and do not need any form of approval or certification.

If you are unsure whether your renovation crosses the threshold, contact a certifier or your local council. A quick conversation can save you from starting work that turns out to need approval.

Do I need a building certifier for a granny flat in NSW?

Yes, in almost all cases. A granny flat (secondary dwelling) requires either a Complying Development Certificate or a Development Application (DA) followed by a Construction Certificate, plus a Principal Certifier to conduct inspections throughout construction and issue the Occupation Certificate (OC) at completion.

Many granny flats qualify for the CDC pathway under the SEPP (Exempt and Complying Development Codes) 2008, which is the faster route. To be eligible for a CDC, the granny flat typically needs to meet criteria including:

• The property must be in a zone that permits secondary dwellings
• The total floor area of the granny flat must not exceed 60 square metres
• The property must meet minimum lot size requirements
• Setback, height, and floor space ratio standards must be met
• The property must not be in a heritage conservation area, flood-prone land, or bushfire-prone land (depending on the specific controls)

If your granny flat does not qualify for a CDC, you will need to go through the DA pathway with council, and then engage a certifier for the Construction Certificate and inspections.

For more detail on CDC eligibility, see our guide to Complying Development Certificates in NSW.

What other projects need a building certifier?

Beyond renovations and granny flats, here are other common residential projects and whether they require certification:

Swimming pools

Yes. New pool installations require approval (CDC or DA + CC) and a certifier to inspect and sign off the work. Existing pools may also need a compliance certificate to confirm they meet current safety barrier requirements. Learn more about pool approvals.

Demolition

Yes, in most cases. Demolishing a building or structure typically requires a Development Application and a certifier to oversee the process. Even partial demolitions (removing a section of a building) can require approval depending on the scope. Learn more about demolition approvals.

New houses and duplexes

Yes, always. Any new dwelling requires a CC or CDC, a Principal Certifier for all six mandatory critical stage inspections, and an Occupation Certificate before you can move in.

Knockdown and rebuild

Yes. This combines demolition approval and new build certification. You will need a certifier for both the demolition and the new construction.

Commercial fit-outs and change of use

Yes. Changing the use of a building (e.g. from retail to food premises) or conducting a commercial fit-out typically requires a CC and inspections. Learn more about commercial approvals.

Retaining walls

It depends on the height and location. Small retaining walls (generally under 600mm in height) may qualify as exempt development. Taller walls or walls near boundaries, drainage, or buildings typically require approval.

Fences

Most residential fences qualify as exempt development if they meet standard height and material requirements. However, fences in heritage areas, near classified roads, or exceeding standard heights may require approval.

Decks and verandahs

Smaller, low-level decks may qualify as exempt development. Raised decks, covered verandahs, and structures attached to the building usually require approval and certification.

Can I change my building certifier mid-project?

Yes, you can change your certifier at any point during the project. The process involves three steps:

• Notify the outgoing certifier. Advise your current certifier that you are changing providers. They are required to transfer all relevant documentation, inspection records, and certificates to the incoming certifier.
• Engage the new certifier. The new certifier will review the project file, assess what work has been completed and what inspections have been done, and determine whether they are comfortable taking over. They may need to conduct their own assessment of work already completed.
• Lodge the new appointment. The new Principal Certifier appointment is lodged via the NSW Planning Portal. Until this is done, the new certifier cannot conduct inspections or issue certificates.

There are some practical considerations to keep in mind:

• The new certifier is not obligated to accept the previous certifier’s assessments. They may want to verify certain work themselves, which could mean additional inspections.
• There may be a short pause in inspections while the transition happens. Plan for this if your build is time-sensitive.
• If you are changing certifiers because of poor service or concerns about compliance, document your reasons. This can be useful if issues arise later.

Changing certifiers is simpler than most people assume. The important thing is not to stay with a certifier you have lost confidence in. Your certifier is there to protect your interests, and if they are not doing that, finding one who will is the right move.

What is exempt development and when does it apply?

Exempt development is building work that does not need any approval, certificate, or certifier. It is defined in the SEPP (Exempt and Complying Development Codes) 2008 and applies to work that is minor, low-risk, and meets strict criteria for size, height, setback, and materials.

Common examples of exempt development include:

• Garden sheds under a certain size (generally 20 square metres and under 3 metres high)
• Standard residential fences up to 1.8 metres
• Internal non-structural alterations
• Painting and decorating
• Minor repairs using similar materials
• Small satellite dishes and antennas

The catch: exempt development has strict conditions. If any condition is not met (for example, the shed is 1 metre too close to the boundary), the work is no longer exempt and requires approval. Always check the specific exempt development criteria for your type of work before assuming it qualifies.

You can check whether your work qualifies as exempt development through the NSW Planning Portal or by contacting your local council.

How do you know which approval pathway applies to your project?

NSW has three main approval pathways. Which one applies depends on what you are building, where you are building it, and whether your project meets specific standards:

• Exempt development: No approval needed. The work must meet all exempt development conditions in the SEPP. No certifier required.
• Complying development (CDC): A single certificate issued by a private certifier or council. The project must meet all complying development standards in the SEPP. Faster than the DA pathway (typically determined within 10 business days). A certifier is required.
• Development Application (DA) + Construction Certificate (CC): Two-stage process. Council assesses the DA (planning merits). Once approved, a certifier issues the CC (building compliance) and conducts inspections. This pathway applies when the project does not qualify for exempt or complying development.

If you are unsure which pathway applies, a certifier can assess your project and advise you. This is often the quickest way to get a clear answer, because the certifier knows the standards and can tell you immediately whether your project qualifies for the faster CDC pathway or needs a DA.

Key takeaways

• Most building work beyond minor cosmetic changes requires a certifier in NSW. When in doubt, check before you start.
• Granny flats almost always need certification, and many qualify for the faster CDC pathway.
• Renovations that affect structure, waterproofing, fire safety, or plumbing require a Construction Certificate or CDC and a Principal Certifier.
• Exempt development is limited to minor, low-risk work that meets strict conditions. Do not assume your project qualifies without checking.
• You can change your certifier mid-project. The process involves notifying the outgoing certifier, engaging a new one, and lodging the new appointment via the NSW Planning Portal.
• A certifier can quickly tell you which approval pathway applies to your project, saving you time and uncertainty.

The safest approach is always to check before you build. A five-minute conversation with a certifier can confirm whether your project needs approval and which pathway to take.