The Difference between Duplexes, Dual Occupancy Homes, & Dual Key Homes

The Difference between Duplexes, Dual Occupancy Homes, & Dual Key Homes

10 April 2024

As our cities grow and space becomes more scarce, it is a natural progression of urban expansion to want to more efficiently utilize land and increase the density of individual dwellings to cater for a growing population. In inner city areas, this is usually realized by way of large apartment and high-rise unit blocks, but in outer suburban areas which are characterized by detached houses, the advent of dual occupancy properties (a single title property with two separate dwellings on it) has recently experienced a surge in popularity.

While the traditional duplex (a single dwelling structure split into 2 separate units) has been around for some time, the concept of the dual occupancy property is a more recent addition to the real estate lexicon. But there are a number of different types of this style of property and key differences between them, which many buyers and sellers find to be quite confusing.

Let’s take a look at the key differences in more detail.


Duplexes are a single building divided into two separate units, both with their own title


The traditional dual occupancy property has been known historically as a duplex – Which is a single residential building split into two separate units separated by a dividing wall. Duplexes are normally strata titled, which means each unit holds its own individual title and can be sold separately the same as you would a unit or townhouse.

As a property owner, you may own both units of a duplex or just one, and in some cases a small body corporate would need to be set up to deal with the maintenance and administration of the common areas on the property. The properties may be purpose built as duplexes or in some cases (mainly in inner city locations where there are a large number of much older homes), it may be an old house which has been reconfigured into two units.

Dual occupancy homes are a property with one title but with two separate dwellings built on it

Dual Occupancy Properties

Distinctly different to the traditional duplex, a dual occupancy home (often colloquially referred to as a “dual-occ”) is a property with one title and owner, but features two separate dwellings – Which are characterized as being the main and auxiliary dwellings. In most cases, they are houses on slightly larger than average suburban blocks which have had an auxiliary dwelling or “granny flat” added to a previously undeveloped portion of the land, although double-storey homes which have been reconfigured to have separate units upstairs and downstairs are not uncommon.

These two dwellings will have their own exclusive access points and are (in most cases) separately metered for water and power and as such, they can be legally occupied by two separate parties, which makes them popular with investors looking for high rental yields. The number of bedrooms and bathrooms permitted in the auxiliary dwelling are generally subject to restrictions, depending on which city council area the property is in.

Dual key homes are a specific type of dual occupancy property, with two separate dwellings under one roof

Dual-Key Homes

A specific type of dual occupancy property, dual-key homes are similar to duplexes in that they feature two units in one building, but unlike duplexes they cannot be strata titled (meaning the two units cannot be sold or owned separately), and the units themselves are specifically built as main and auxiliary dwellings – Technically making them a dual occupancy property but one where the two dwellings are both under one roof.

Because the two dwellings are individually metered and separated by a firewall, they can legally be occupied by separate parties which once again makes them a popular choice among investors. Interestingly, dual-key homes feature facades that are designed to look like a normal house, rather than a dual occupancy property. They are also subject to the same restrictions on bedrooms and bathrooms as other dual occ properties.

‘Til next time, ciao 😊


Disclaimer: The information is this article is for general information only, it is not intended and should not be considered as either legal or financial advice. The information contained herein should not be relied upon solely and all parties are encouraged to obtain their own independent advice before making any financial decision.
Lee Knutsen

Article by Lee Knutsen

Co-founder & Managing Director of House, Lee Knutsen first entered the real estate industry in 2006 as a residential sales specialist. After more than a decade as a sales agent…

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