How Much Does a Home Extension Cost? [2024]

The time comes to many homeowners when they have to make a decision: "Shall we sell and buy a larger home or add on a home extension?" If you're happy with your current location, a home extension can be less disruptive to your life than moving and add value to your home.


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How Much Does a Home Extension Cost?

On average, home extensions cost:

• $1350m2 for a timber ground floor extension
• $1500m2 for a brick veneer ground floor extension
• $2100m2 for a first floor extension

These average costs can be deceiving. A first floor extension can cost less than a ground floor addition in some cases and any extension can cost  much less or more than the average depending on the inclusions.

Costs Associated with a Home Extension

In order to come to a more realistic estimate of the costs associated with your home extension, you need to consider both general costs and the costs specific to your extension. Every home extension will require council approval. In order to get that approval, you will have to submit detailed plans drawn up by a professional drafter. In some cases, you may need to hire a structural engineer.

Builders costs can vary, but the biggest variations in the per square metre cost of extensions are usually in the inclusions.

Outside, the difference between timber and brick veneer is about $150 per square metre, but full brick will be more and if you add rendering, the cost per square metre will be even higher. There are significant differences in the costs of roofing materials, too, and don't forget to include guttering and other details.

Inside, you have flooring, lighting and other inclusions to cost. Seemingly minor costs can add up to hundreds of dollars per square metre. When you do your costings, leave room for less expensive inclusions if it looks like you're going over your budget.

After you've done your costings, add a 10 percent buffer to account for unforeseen expenses. If you can afford the extra 10 percent, you can probably afford your extension. If not, look at ways to trim your costs.

It's best to do preliminary costings before you get quotes from builders. That way, you can get more accurate quotes from builders and make more informed decisions when you sit down and iron out the details of your extension. When getting online quotes from home extension builders, give them details about anything that might affect the cost of the extension. If you're building on a sloping block, for example, they will need to take this into consideration.

*Cost and prices in this article are indicative and should only be used as a guide. They also vary locally and are subject to market forces.