Develpr guide

Knock-down Rebuild in NSW: What Can I Build Instead?

Rebuilding usually makes sense when the existing house is tired, poorly oriented or too small to extend sensibly. The question is not really whether you can demolish. It is what the controls will let you build in its place.

This guide covers the approval side of a knock-down rebuild in NSW and the checks that protect you before you sign with a builder.

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The short answer

In most residential zones you can demolish a house and build a new one, provided the demolition and the new dwelling are approved. Some rebuilds can be approved as Complying Development where the new home meets every standard in the housing code and the site is not excluded. Others go through a Development Application.

The size and shape of the new home is set by the floor space ratio, height limit, setbacks, site coverage, landscaping and private open space controls for the property. Heritage listing, a conservation area, flooding or bushfire can change the answer, so the property itself needs to be checked before you commit.

What does a knock-down rebuild involve?

Two pieces of work: demolishing the existing structure, and building the replacement. They can be approved together or separately depending on the pathway.

Demolition itself is regulated. There are notification, waste, asbestos and safety requirements, and on some sites demolition needs its own consent. Heritage sites are the obvious example, where demolition may not be supported at all.

The upside of a rebuild is that you start with a clean site, so you can use the full building envelope the controls allow rather than working around old walls.

Could this work on my property?

The rebuild question is really an envelope question. What can the controls allow on this lot?

Zoning: The zone confirms that a new dwelling house is permitted and whether other options, such as a dual occupancy, might also be available.
Floor space ratio: This usually sets the total size of the new home, and is the number most owners are surprised by.
Building height: Height limits and storey controls determine whether two storeys, or an attic level, are realistic.
Setbacks and site coverage: These shape the footprint, particularly on narrow or shallow lots.
Landscaping and open space: Minimum landscaped area and deep soil zones cannot be built over, which reduces the usable footprint.
Heritage: A listed item or a conservation area can restrict or prevent demolition, and will influence the design of any replacement.
Trees and site conditions: Protected trees, slope, rock and drainage all affect where the new house can sit and what it costs.
Other options for the site: Before rebuilding one house, it is worth knowing whether the lot could support a dual occupancy or additional dwelling instead.

What should be checked first?

Whether demolition is supported on the site, especially if there is any heritage status.
The building envelope allowed by floor space, height, setbacks and site coverage.
Whether the lot could support more than one dwelling, which changes the financial picture.
Flood, bushfire, land slip and contamination mapping affecting the property.
Trees on and adjoining the site, and the reports likely to be required.
Services, easements and sewer location, plus any build over approvals needed.
Whether the property is excluded from the Complying Development pathway.

Will I need a DA or CDC?

Complying Development

A Complying Development Certificate is a fast, standards based approval. It is only available where the proposal meets every applicable requirement and the site is not excluded. Miss one standard and the pathway is gone.

Development Application

A DA is lodged with the council and assessed on its merits, with notification to neighbours in most cases. It takes longer, but it allows design that does not fit neatly inside the codes.

New dwelling houses are one of the most common uses of the Complying Development pathway, because the housing code sets clear standards for lot width, setbacks, height and floor area.

Sites affected by heritage, significant flooding, some bushfire categories and other exclusions cannot use that pathway, and designs that break a standard cannot either. Those projects go to the council as a DA.

Demolition is dealt with as part of the approval, either within the certificate or the consent, together with the required waste and safety conditions.

What can affect the opportunity?

Heritage

Demolition of a heritage item is rarely supported, and in conservation areas the replacement design is closely controlled.

Flooding

Flood planning levels can dictate floor heights, materials and even where habitable rooms can be located.

Bushfire

Bushfire prone land sets construction standards and asset protection zones that influence siting.

Narrow lots

Lot width drives the code pathway and the practical footprint, and narrow frontages limit garage options.

Trees

Removal of significant trees may not be approved, and root zones can restrict excavation.

Contamination

Former uses, fill or asbestos can require investigation and remediation before building starts.

Slope and rock

Excavation, retaining and stormwater on sloping sites add cost that is easy to underestimate.

Rebuilding in one of these areas?

What should I do next?

Before signing a build contract or a full design fee, check the property and the controls that set the building envelope. That tells you what you are actually buying.

If the numbers look right, a Registered Planner can review the site, confirm whether a better development option exists and help set the approval pathway.

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Common questions

Can I demolish my existing home in NSW?

In most cases yes, with approval. Demolition is regulated for safety, waste and asbestos, and it is usually approved as part of the consent or certificate for the new dwelling. The main exception is heritage. If the house is a listed item or contributes to a conservation area, demolition may be refused or heavily restricted, and specialist heritage advice is needed early.

Can I build a larger home than the one I am demolishing?

Often yes, because many older houses use far less floor area than current controls allow. The limit is set by the floor space ratio, height, setbacks, site coverage and landscaping requirements for your property rather than by the old house. On constrained or heritage affected sites the opposite can be true, so the envelope needs to be worked out before design.

Do I need a DA or can a rebuild be a CDC?

New dwelling houses are frequently approved as Complying Development where the lot and the design satisfy the housing code in full. Sites excluded from the code, or designs that vary a standard, need a Development Application assessed by the council. The CDC route is faster but inflexible, so the design usually has to be shaped around the standards from the start.

Does heritage prevent a knock-down rebuild?

It can. A heritage listed dwelling is unlikely to be approved for demolition. In a heritage conservation area, the position depends on whether the house contributes to the character of the area. Sometimes a rebuild is possible with a sympathetic design, and sometimes only alterations and a rear addition will be supported. Heritage advice before design saves significant money.

What should I check before engaging a builder?

Confirm the planning envelope, the approval pathway and the site constraints first. Builders price what is drawn, and drawings that ignore the controls get redrawn. Also check services, easements, sewer location, tree issues and any contamination risk, since these are the items that turn up mid project and blow out both program and cost.

Can I add a secondary dwelling at the same time?

In many residential zones a new house and a secondary dwelling can be approved together, which is a common way to add rental income or accommodate family. The combined proposal still has to satisfy floor area, setback, open space and parking requirements. Designing both at once is usually cheaper and produces a better result than adding a granny flat later.

Should I rebuild one house or look at two dwellings?

Worth testing before you decide. If the lot meets the minimum size and frontage requirements for dual occupancy in your zone, two dwellings can be worth considerably more than one large home. It also costs more and takes longer to approve. The right answer depends on the controls for your property and what you want from the site.

Professional review

Get professional advice for your property

Online guides explain the general position. Your property needs to be assessed against the controls that actually apply to it.

Where appropriate, a Registered Planner can review the opportunity and help you understand what may realistically be achievable.

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Related guides

Sources

The planning position described on this page is drawn from the following sources. The requirements that apply depend on the planning controls applying to the individual property, so always confirm the current position for your site.

Planning content reviewed by a Registered Planner. This guide is general information only and is not planning advice for a specific property.

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