29 July 2026 | See disclaimer
In 2026, Australian house extension costs typically range from $2,000 to over $4,000 per square metre for a ground-floor extension. That means if you’re looking to extend your home by 80 square metres, you can expect to pay anywhere from $160,000 to $320,000. [1] While these prices can vary significantly, Australians are still embracing home extensions as a worthwhile investment.
Currently, there is a large surge in building productivity, with the Australian Bureau of Statistics reporting that alterations and additions to homes rose to $3.7 billion in the September quarter of 2025. This means more Australian homeowners are actively choosing to spend on house extension upgrades to increase their living spaces and property value. [2]
If you’re considering creating extra space with a second-storey or a small extension to the ground level of your home, this guide will break down some of the costs involved. This way you can set a realistic budget for your extension — no matter how big or small.
All costs listed are estimates, and depending on the specific scope of your project, we recommend you seek multiple, detailed quotes from qualified builders.
Australian Home Extension Costs
While exact costs vary from project to project, here’s a rough guide for different-sized extensions:
| Size of Extension | Costs |
|---|---|
| 60m² | $20,000-$75,000 depending on the quality of inclusions |
| 80m² | $160,000-$320,000 |
It’s best to note that simple ground-floor extensions are cheaper in comparison to more high-end and complex projects. Larger additions, including bathrooms, laundries and kitchen renovations, will most likely result in higher costs due to the complex work that’s required by tradesmen.[1]
If you decide to add luxury finishes and bespoke designs to your renovations, this can also increase the price, so be sure to discuss these ideas with your builder or architect during the quoting stage to avoid any unexpected costs and to keep your budget on track.
When you’re making renovations and adding upgrades to your home, you should also consider your sum insured amount, which is the amount used to cover the costs to rebuild your house. Renovating your home will likely increase the overall replacement value of your property. This means if you haven’t increased your sum insured amount and an insured event, such as a fire, destroys your home, you may be left out-of-pocket to pay the gap to rebuild. If you’re unsure how to calculate an accurate sum insured amount, you can get an estimate from the Home and Contents Replacement Cost Calculators.
Example Project Costs: 3 & 4-Bedroom Extensions
3-Bedroom Extension (90–120m²):
Are you planning to expand your home with extra bedrooms? Based on the average extension cost per square metre, a three-bedroom extension of 90-120m² in total can typically cost anywhere between $180,000 to $480,000.[1]
4-Bedroom Extension (120–150m²):
If you’re looking to upgrade your home to an additional four bedrooms, the cost will further increase due to the extra bedroom and larger space to build. For these larger extensions, you can expect to pay anywhere from $240,000 to $600,000. Given the broad price range, it’s recommended that you include a 10-15% contingency in your budget in case of any unforeseen expenses that may arise and push the total cost beyond initial estimates.[1]
What Are the Most Expensive Parts of a House Extension?
Wet areas such as bathrooms, kitchens and laundries can be the most expensive rooms to build due to their intricate spaces and expensive materials. These can be more expensive per square metre compared to dry rooms because they require a blend of plumbing, waterproofing, electrical work and fixtures by specialised trades. For example, just adding a new bathroom can cost you anywhere from $8,000 for a simple basic renovation to $35,000 for a premium bathroom build.[3]
Keep in mind that renovations to wet areas will need to adhere to waterproofing standards, as seen in the Australian National Construction Code (NCC 2022). This is crucial for trades who are waterproofing to follow so as to prevent moisture-related issues such as mould growth and gradual leak problems caused by wear and tear,[4] which aren’t typically covered by your Home Insurance policy.
The primary cost that makes wet areas more expensive to complete is the need for durable, premium materials such as benchtops and tiling that combine functionality with style. Not to mention, the craftsmanship and time it can take to install and tile, especially if you choose smaller or more intricate tile designs.
If you’re looking to reduce the costs for your wet area extensions, we recommend considering your choice of tiles and limiting luxury features such as spa-style ensuites and expansive kitchens to save on the overall cost.
Key Factors That Drive Your Final Extension Cost
Ground Floor Extensions vs. Second-Storey Extensions
Adding an upper floor can be an excellent way to have more space without the hassle and disruption of moving.
However, building a second-storey extension can cost you up to 50% more than building out on the ground floor, depending on the degree of difficulty and structural reinforcement that’s required. Although this can be quite expensive, it’s also worth noting that a second level can also add 30%-60% more to the value of your home when you go to sell![5]
The costs for adding a second-storey can range from $1,850-$3,500 per square metre for a simple build or up to $15,000 per square metre for a larger, high-end and complex space. To manage these expensive costs effectively and navigate the complexities of a second-storey project, hiring relevant tradespeople and other contractors can help you keep everything in check, including your budget. Town planners, building surveyors, certifiers, architects or draftspeople, and your site manager can help guide you through the necessary checks. While local council approvals and building regulations ensure your extension is in line with the National Construction Code throughout the construction phase.[6]
You can expect to pay the following figures for a second-storey extension:[6]
| Size of Extension | Costs |
|---|---|
| 60m² | $110,000-$300,000 |
| 80m² | $148,000-$600,000 |
| 100m² | $185,000-$750,000 |
Labour & Construction Prices
Due to labour shortages and expensive materials, house extension costs in 2026 can be a costly figure. The Housing Industry Association (HIA) recently released a Trades Report, showing a reduced number of tradesmen in the workforce compared to the prior quarter in mid-2025, revealing a further decline in available skilled labourers.[7]
Coupled with fewer trades, this has caused a ripple effect on the overall construction prices around the country. As reported by Master Builders Australia, labour shortages are likely to drive building and construction costs up by 3%, increasing the price of materials and professional services.[8]
For example, in December 2025, the cost of timber, board and joinery rose by 0.4%, and cement products rose by 1.6%. These fluctuations in material prices directly impacted home building costs, with output to the house construction price movements rising in the quarter by 1.5%.[9]
This is why budgeting effectively for your home renovation project before commencing is so important, so you can accommodate for any sudden price rises and other costs. As building prices increase, it’s also worth factoring in any potential increase to the cost of your Home Insurance cover. When you’re renovating, your home’s replacement value may rise; therefore, it could be worth increasing your sum insured amount to ensure it accurately reflects any change in value.
Average Labour Costs
When adding an extension onto your home, you can expect to pay on average 50% for materials, 35% for labour and 15% for council fees and permits.[10]
Depending on where you’re based, the figures below can fluctuate due to location and inflation, but are a rough guide:
- Bricklayer: Bricklayers repair bricks, lay stonework and usually come in pairs to mix the cement costing from $58-$110 an hour.[11]
- Concreter: Concreters are responsible for mixing, pouring and finishing concrete for your floor, ramp or outside areas. Depending on their experience, they can charge $60-$150 per hour.[12]
- Builder: Expect to pay upwards of $90-$150 per hour for a builder to work on your home extension.[10]
- Electrician: Electricians, best known as ‘sparkies’, can charge from $80-$100 per hour, specialising in electrical wiring and equipment.[13]
- Tiler: To fully complete any wet area, you’ll need to hire a tiler. These tradesmen are responsible for cutting tiles, applying grout and waterproofing, charging from $45-$150 an hour.[14]
Professional Fees
Before any extensions begin, it’s best to consult an architect to ensure you have the proper reports and drawings in place. Architect fees can vary greatly, with design consultations costing $100-$250 per hour, concept designs costing $2,000-$5,000, renderings up to $3,000 and construction documentation ranging from $5,000-$15,000.[15] However, if you want to save on costs and your project is simple, you can consider consulting a draftsperson to see if they’re more suitable for your extension work.
Surveyors, on the other hand, can cost from $90-$170 per hour, which depends on the size and shape of your site,[16] and structural engineers can cost from $90-$190 an hour.[17]
| Professional Fee | Average Cost |
|---|---|
| Architects[15] | $100-$250 per hour |
| Surveyors[16] | $90-$170 per hour |
| Structural Engineers[17] | $90-$190 per hour |
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Frequently Asked Questions (FAQs)
Is it cheaper to extend or move?
In short, it depends on what type of extension you want to complete. If it’s a smaller-scale project, this may be cheaper for you in comparison to purchasing a new home. It also depends on how much you’d end up selling your home for and the purchase price of the new house. However, when it comes to buying a new home, this can come with many expenses, including agent commissions, stamp duty, legal fees, moving costs and other expenses. A home extension will let you reside in your existing home and suburb while adding your own touch to the residence to suit your lifestyle needs, and if planned strategically, it can be a more cost-effective option compared to moving.
Is it cheaper to extend up or out?
Determining whether it’s cheaper to extend up or out depends on the material prices, labour costs, size of the extension, and whether you wish to add any luxury features to your design. Adding a second-storey can cost up to 50% more than a single-storey extension, with prices ranging significantly from $110,000-$750,000 depending on design complexity and finishes. An additional storey can also come with more structural work, such as removing the roof and reinforcing existing structures, which can make labour costs more expensive. However, the price difference between the two extension options differs from household to household, depending on your design ideas.
How long does it take to do a house extension?
The timeline for your house extension varies on whether you’re building out on the ground floor or adding a second-storey. Based on the size and complexity, extensions can last from 3-6 months for a lower-level renovation and up to nine months or longer when adding a second-storey extension to your house.[18]
