How Much Does a House Extension Cost?


Expect to spend up to $4000 per square metre if it’s a ground floor extension. Aside from the structural materials for the roof, walls and floor, you also have to think about the heating and air conditioning, electrical and plumbing system of the resulting extension.

How much does a house extension cost?

If you’re planning to have an extension of around 80 square metres, it will take up to $320,000. It’s just a rough estimate because the total costs depend on the quality of materials, fittings and finishes as well as the complexity of the project (i.e. if it takes too long it’s a lot more expensive or you require a new kitchen and bathroom there).

Because of the costs, many homeowners consider having a smaller extension (e.g. around 60 square metres). Others also consider converting an existing garage into a room instead of making an extension from scratch. Aside from the costs, homeowners consider those options because of the available or limited outdoor space.

What about prefabricated home extensions?

If you want to save money and get it done faster, there are now prefabricated home extensions available. There are already set designs you can choose from which might already be great for your home and your requirements.

However, the designs and options are limited and they won’t perfectly match your requirements. You might also want several specific details to be included in your resulting extension. Also, you want the extension to complement the look and feel of your main home structure and your outdoor space. It’s important to think about those before choosing a prefab.

Other things to consider

It’s crucial to consider all costs from start to finish including the council fees as well as the potential excavation and demolition work. Think of it as building a new house instead of just an extension because of the work, costs and attention required for its successful and timely completion.

It’s also great to work with experienced professionals for such projects. After all, the extension has to be done right the first time and that you should be delighted with the results. It’s a huge investment which also has the potential to deliver huge value to you as the homeowner.