What is a duplex house?

A duplex is a residential home divided into two units. These two units share a wall, but are considered separate homes. The two units of a duplex may belong to one person who rents one out or uses both, or they can each be owned separately on their own individual titles.

Duplex units can be laid out in many different combinations. The most common duplex layout in Australia is side-by-side, but sometimes they are separated into upper and lower levels instead. Side-by-side duplexes are also known as twin or semi detached houses. The main indicator of a duplex is the two units share a building but have separate entrances, and that one unit cannot be accessed from inside the other.

Benefits

There are a number of benefits to purchasing a duplex home rather than a traditional home. For one, the cost of building a duplex is significantly less than building two separate houses. The average cost to build a duplex in 2019 was $1-$1.1 million, which is more expensive than building a single house, but far cheaper than trying to construct two (especially when considering the amount saved on land costs).

Another benefit to owning a duplex is that you have the opportunity to both live and rent out your property. Many choose to live in one half of their duplex and rent the other to gain some mortgage relief income. It also maximises profits for those looking at getting an investment property, as it can double the income stream coming from the single property. Duplexes are very financially reliable as if you are renting the property out you may be able to tax deduct some of the repairs.  

A duplex is also well suited for personal use, as it allows you the owner to house family in their own private space whenever needed. This is a great safety net for young adults moving out for the first time, family who need a little help, multigenerational setups, caring for elderly family members, and to house those who are visiting for long periods of time (such as overseas relatives).

Layout

When it comes to duplex design, there are a number of possibilities. Duplexes do not always have to be a 50/50 split, and the common wall does not always have to be straight down the middle. The two-story duplex is a great example of this, because it is a creative way of maximizing the space for both properties without having to combine them. Note that a duplex will never have more than two storeys (otherwise it becomes a multi-plex).

Semi-detached houses / side by side duplexes are one of the most common duplex layouts. Homes like these will usually be split evenly down the middle and have mirror-image doors. The internal floor plans of a duplex are also usually symmetrical, with one unit appearing like a reverse image of the other. It is a similar story for two-storey duplexes, which often have an identical layout regardless of which floor they are on. To give you a better understanding of the types of duplex designs available, here is a list of some of the different categories and floor plans.

Duplex designs floor plans: The best duplex house plans and prices for a modern Australian home

4. Duplex floor plans for a small home

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A tiny duplex is a great way to make the most of every inch of available space. This home plan has a clever division that makes it appear like a regular two story single home from the outside. The front door of this home leads to a foyer which has two separate entrances into the respective units.

Both homes have an upstairs and downstairs floor. The upstairs contains a living room, study/storage area, spacious kitchen and dining area, and access to the patio. Upstairs, there is a full bathroom, large closet, and two bedrooms (one with a balcony). This design manages to pack all of that into just over 93 square metres – a truly impressive feat.

3. Cheap

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For affordable duplex house plans, look no further than House Plans.com. These floor plans are comprehensive and exact, providing you with a high quality design without the extravagant fees of an architect. The plans for this duplex are currently on sale for just $820 – a fraction of the typical 5% build fee that an architect or draftsmen would charge.

The two semi-detached units of this home have slightly different interior layouts. Though both have a large living area (around 179 square metres), the left house has a larger master bedroom and a kitchen which faces the inside of the house. The kitchen in the right unit overlooks the yard. Both homes have a large entrance hall, plenty of windows, a living room, dining room, laundry closet, and bathroom with a large shower.

2. Modern side by side house

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For a duplex with a contemporary flair, consider this flagship duplex by Provincial homes. This design is well suited for a life on narrow blocks and features large bedrooms, kitchens, and open plan living. The home is split in half through the middle, with each unit having an upstairs and downstairs area. However, the units are not identical in size.

Unit one features four bedrooms, two bathrooms and an ensuite, and one car space. It is 239 square metres. The second unit has all of the above as well as a study area, though it only comes to about 229 square metres total.

1. 2 Storey

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The double storey duplex is without a doubt one of the best duplex designs available. The double storey townhouse pictured above presents a new outlook on modern city living. Architect designed by Woodsman Projects – an up and coming building company based in Melbourne – this elegant home makes the most of every spacious inch, with four bedrooms and two car spaces slotting easily into place.

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And the best part? They construct it too. See here for the build price.

If you are more interested in constructing a home yourself, see here for some of Australia’s best prefab homes.