How much does a home extension cost in Sydney?

Quite literally the Million Dollar Question and the question I get asked more than almost any other- how much is this going to cost? And the honest answer is — it depends. It depends on the scope and the quality, availability of trades, style of construction….so many factors. But there are real numbers worth knowing before you start planning.

Let me give you the framework for understanding renovation and extension costs in Sydney — because the numbers vary enormously depending on who you ask. Your building designer and your builder will give you one figure, and your mates will tell you that they are wrong and they built for a fraction of that cost.

As a broad guide, construction costs in inner Sydney for quality residential work can be in the range of $8,000 to $12,000+ per square metre for new built area — depending on finishes, site conditions, and how complex the work is. A rear extension with a good level of finish canland toward the lower end of that range.

Why the high costs?

Well, most of us have seen Grand Designs. The homeowner moves forward with the build without a clear budget, they make changes, ‘must have the Scandinavian tap ware……..ooh, and the $80,000 oven’, they haven’t finalised decisions and had them costed before they start building. “Scope Creep”, or “while we’re doing it” inclusions can add dramatically to the build costs

Square-metre rates are only part of the picture. Fixed costs — demolition, site preparation, connection to services, site access, contamination, scaffolding, heritage, proximity to other buildings, geomorphology, professional fees, approvals and certification — don't scale linearly with size. Renovating an existing space can be costly without adding floor space. A smaller extension can cost proportionally more per square metre than a larger one because those fixed costs are spread across less built area.

Fees can vary dramatically as well. An Architect can charge typically 10-18% of the build cost, when maybe a Building Designer, with a membership of the BDAA can cost you 3-7% for much the same quality of service and design. A fixed fee, as opposed to a “percentage of construction cost’ fee also means that there is no advantage for the designer if the costs blow out.

For a typical rear ground floor extension in the Sydney Metro area a realistic all-in budget including professional fees, council fees, and contingency can vary dramatically. We have seen budgets of $450,000 to $2,500,000 for renovation projects and everything else in between.

The most important number is your total budget — not the per-square-metre rate. Designing to a budget that's realistic for your scope, site, and finish level is one of the most useful things I do early in a project. It avoids the expensive problem of designing something you can't build for what you have.

If you are wanting to save the hassle and headache of spending thousands on finding out even if you can achieve your dream, our Exploration Package, at $795 is a great way of answering a lot of your concerns at the outset of your journey.