Adding an extension to your Melbourne property is a significant undertaking involving architectural plans, building permits, and construction work. As of December 2025, costs vary widely depending on the size, complexity, and finishes chosen.
Currently in Melbourne, a basic, single-storey extension – say, adding a bedroom and bathroom – can range from $2,500 to $4,000 per square metre. More complex extensions, involving structural changes, kitchens, or multiple rooms, can easily exceed $5,000 per square metre. In the Eastern Suburbs, where properties often have established gardens and tighter block sizes, site access and landscaping can add to these costs. It’s important to realise that these figures don’t include professional fees like architects, engineers, or council permits, which can add 10-20% to the overall project cost. When preparing to sell, a well-executed extension can significantly favour your property, particularly in areas like Balwyn and Doncaster where families prioritise space. However, overcapitalising is a risk; in 2026, buyers will assess value based on comparable sales, and a lavish extension may not yield a dollar-for-dollar return. Fletchers’ appraisals consider recent renovation costs and their impact on market value.
Ultimately, the cost of an extension is a substantial investment, and careful planning is essential to maximise its potential return, both for enjoyment and future saleability.