One Block, Two Houses – Dual Occupancy



One Block, Two Houses – Dual Occupancy

Dual Occupancy is two dwellings on a single allotment of land.

In Sydney, most Councils will allow the original lot to be subdivided into two separate lots. 
The main advantage of Dual Occupancy is by creating more than one residence on your block you are significantly increasing the value of your property.

Types of Dual Occupancy Homes


The most popular form of Dual Occupancy is where the existing home is demolished and removed, and two new dwellings usually attached are built. This type of Dual Occupancy is usually known as building a duplex.

Duplex building in Sydney is immensely popular at the moment, with hard working Australian families realising that this is a good way to financially secure theirs and their children’s future.

While any form of Dual Occupancy will add value to a property, building a duplex is by far and away the best option. When you build a duplex, it is usually double storey and the two dwellings face the street. Having the two dwellings facing the street is an important consideration to potential future purchasers.

With the correct front façade treatment to the casual observer the duplex appears to be a single house.

As most duplex homes are double storey this allows you to build a much larger dwelling than would be possible with other forms of Dual Occupancy.

To build a four bedroom, two bathroom single garage double storey duplex, the price would start from $650,000. The final price will be known once all Council conditions and the constraints of the existing lot are known.

With regards to subdivision of the duplex, this can only take place when the duplex has been built and the plan of subdivision has been approved.

Granny Flat

The simplest form of Dual Occupancy is a secondary dwelling (granny flat) in the back yard, as granny flats are limited size to a maximum 60m2 they can fit into most back yards. And due to their relatively small size they can be approved by a private certifier which means you don’t have to go through council.

And the best news is that granny flats are the least expensive form of Dual Occupancy. A typical brick veneer granny flat will cost about $140,000 to construct.

One important point to keep in mind about granny flats is that you cannot subdivide the lot and get separate title for the granny flat.

The granny flat will be on the original title and when you go to sell your property you will be selling it as a house with self-contained separate accommodation.

Building a granny flat in your back yard has many advantages such as:

  • Provides a rental income which will help to pay off the mortgage sooner
  • Can be used as accommodation for an elderly parent who want to be closer to their children and grandchildren
  • The granny flat will add value to your property and will be an appealing proposition to any potential purchasers
  • You get separate self-contained accommodation in your back yard which can have many uses

Second Home on Same Land

The next type of Dual Occupancy is building a second house in your back yard and keeping the existing house.

This type of Dual Occupancy will almost certainly have to be approved by Council and every Council will have planning controls to prevent over development of the lot.

The planning controls will have at least the following as a minimum requirement:

  • Minimum lot size to enable subdivision to occur.
  • Minimum width access way to allow a vehicle to access the rear lot once subdivision has been approved.
  • Height restriction on the dwelling to be built in the rear yard.
  • Council will require a minimum amount of private open space for the existing dwelling and the new dwelling.
  • There will be minimum setbacks from the boundaries for privacy of adjoining properties.

A typical 150m2 single storey three bedrooms, two bathrooms, single garage brick veneer home will start from $250,000. The final price will be determined by Councils requirements for stormwater disposal and the location of existing services on the site.


With this type of Dual Occupancy, the subdivision to create the new lot at the rear of the existing home can only take place after the new home has been built, a plan of subdivision has been prepared by a surveyor and approved by Council.

Once approved by Council the plan of subdivision can be lodged to Land and Property Information (LPI) to register the new lot and create a separate Title. Once the new Title has been created the new home can then be sold should the owner so wish.

When you subdivide an existing lot to create a new lot behind the existing home with access to the new lot down the side of the existing house this is known as a battleaxe lot.

This type of Dual Occupancy is popular where there is enough room between the existing home and the side fence to build an access driveway to service the rear lot.

Most Councils require a minimum 3.5 metres both horizontally and vertically to facilitate vehicle access to the rear property.

Important Considerations to Dual Occupancy Homes

When considering building any form of Dual Occupancy with the exception of a granny flat, an important factor to keep in mind is which way the block of land falls. Most Councils want the rainwater run off to drain to the street or if the land falls to the rear, the run off must be collected and disposed to a stormwater easement.

An easement is a right to run a stormwater pipe underground through one or more adjoining lots so that the rain water can drain by gravity to the nearest street on the low side.

On subdivisions created prior to the 1970, lots that fall to the rear were not provided with storm water easements therefore if the owner of a lot that falls to the rear was considering building a duplex and the lot was created prior to 1970 then they will require an easement through adjoining properties, which will need the permission and agreement of the owner of the adjoining lot.

Even with the permission of the owner it may still not be physically possible to build the easement due to existing structures in the path of the easement.

Discover Your Options

Champion Homes has been building duplex homes for the past 20 years and has experience building on all lot types.

We can advise you on what duplex works best on your land.

To find out more book a free consultation today. 

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