the cost of building a house extension in 2023
House extension costs could be in the tens of thousands. Image: Canva.
  • Adding a few bedrooms could see costs up to $4,000
  • Bathrooms, laundries and similar attract a much higher cost
  • Renting while the build takes place could add over $8,000 to the cost of house extensions

If you need a little more space and love where you live, or maybe you can’t find the right place to call home elsewhere, you may be thinking about building a house extension.

While most Australians were looking for more minor improvements, to their homes, as the cost of living and renting skyrockets, share housing is predicted to be on the rise – with it, the need for more space to call home.

In this guide, we delve into how much does an extension cost, what factors impact the price of house extensions, and other tidbits like whether you can still live in the house while renovations take place.

What affects house extension costs?

Some of the largest factors influencing the cost of home extension include the size, number of rooms, room type, complexity of design, and what materials are employed.

Cost of labour also has a substantial impact, particularly in recent years, along with more minor impacts such as the location of the property, the structural soundness of the current property, along with other administrative matters such as permits and approvals.

Award winning home additions will also add to the cost.

Cost of home extension

The typical cost for an extra room is in the mid $2,000’s, with more substantial home extensions within the order of $4,000.

City Estimated Cost (per square meter) Number of Rooms Room Types
Sydney $2,500 – $4,000 1-3 Bedroom, living room
Melbourne $2,000 – $3,500 1-3 Bedroom, living room
Brisbane $2,200 – $3,700 1-3 Bedroom, living room
Perth $2,300 – $3,800 1-3 Bedroom, living room
Adelaide $2,100 – $3,600 1-3 Bedroom, living room
Hobart $2,000 – $3,500 1-3 Bedroom, living room
Darwin $2,400 – $3,900 1-3 Bedroom, living room
Canberra $2,200 – $3,700 1-3 Bedroom, living room

Estimates can also vary substantially, depending on the type of extension you are looking to build, particularly where significant works such as plumbing, electricity, drainage, and more are required.

Room Type Estimated Cost
Bathroom $12,000 – $28,000
Laundry $6,000 – $15,000
Study $10,000 – $20,000
Home office $12,000 – $24,000
Games room $15,000 – $30,000
Patio $10,000 – $20,000

It is important to note that these house extension costs are estimates and can vary about many factors.

Who is involved in building a home extension

The relevant professionals for planning permission, building permits, council approvals, and building regulations may be required. They may be separate individuals you seek advice from, or some builders may offer integrated services that cover all your paperwork needs.

Aside from that, you may need the services of:

  • Architects,
  • Builders,
  • Plumbers,
  • Electricians,
  • Landscapers, and
  • Conveyancers.

Can I live in the house?

The answer to: How much does it cost to extend a house? Can also vary on whether you are able to stay in the home while the work takes place.

Again, this varies on the type of extension and how intrusive it is to your everyday life. A small extension may not involve demolition or major structural changes, where as major jobs such as a new floor could require you to move out for a short while.

Whether the extension is at the front or rear of the house may also impact how intrusive the job could be and whether you wish to move out.

Construction times will vary on the complexity, scope, and scale of the job, with the timeline typically seeing two to six months of planning and design, with three to 12 months of construction.

Based on CoreLogic rental data, if you need to rent while leaving your house during a home extension build, it could see home extension costs go up by an additional $4,000 to over $8,500.

City Median Weekly Rent 6 Months 12 Months
Canberra $681 $4086 $8172
Sydney $711 $4272 $8544
Melbourne $635 $3810 $7620
Brisbane $604 $3624 $7248
Adelaide $534 $3204 $6408
Perth $583 $3504 $7008
Hobart $550 $3300 $6600
Darwin $620 $3720 $7440

Even so, it may be even more expensive and tough given the tight rental market, with the latest vacancy rates across the nation around 1.2%, according to SQM.


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