The Costs of Adding a First Floor Addition to a Sydney Property

The Costs of Adding a First Floor Addition to a Sydney Property

Want to know about the costs of adding a first floor addition to your home in Sydney?

First floor additions and renovations to your house, semi, terrace, duplex or top floor apartment in Sydney is a great way to increase your accommodation, add value to your house capital gains tax free and stay in your favoured area.

This is far better than relocating because you avoid endless house inspections and auctions, avoid unproductive costs like agents’ fees, marketing fees, moving costs, legal fees, inspection fees and stamp duty which all can be better used towards your first floor addition and renovation, productively.

To prepare for your first floor addition and renovation you need to understand your accommodation requirements, the likely project costs and how much money you have available to carry out your project.


Estimating the project costs can be worked out very broadly once you have established the gross floor area (GFA) of the entire project including both the first floor addition and the renovated area (which could include the ground floor area). 

Multiply the GFA by $3,000 to $4,000/m2 to derive your approximate construction costs for a high quality first floor addition and renovation including fitout. Add 5% to 10% contingency cost, 15% for consultants and authority fees and this will inform you of your likely costs in a “back of the envelope” manner.   


You will need to rent for the construction period which costs will need to be factored in. Of course this “back of the envelope” figure will vary up or down depending on the building materials selection, your finishes selection, if a pool is being built, the extent of landscaping and driveways being included or if you are building on a steep or any site with engineering issues.

If the overall back of the envelope costs are within your budget, then the way to get cost certainty is to employ Domus Homes to carry out the first step in its concept to completion process by designing the sketch plans according to your brief and then having these plans professionally estimated. This will provide you with a high level of budget certainty where your costs will be known within a 5% – 10% range, so long as you don’t change your plans or finishes selected at the time of the estimate. Building materials costs do increase over time though.

Embarking on a first floor addition and renovation is an exciting process where you get the brand new house, semi, terrace, duplex or apartment you want using your own endeavours and made safe, easy and enjoyable with the concept to completion project management and custom design services of Domus Homes within time, budget and quality.



Disclaimer: The above “back of the envelope” costs cannot be wholly relied on without carrying out the necessary design plans and estimates and Domus Homes accepts no liability whatsoever in relation to the above guide.


To find out more, call Domus Homes on 0404 0202 77 or email us at for your free site inspection.

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