You can run the renovate versus rebuild comparison yourself, roughly, before you engage anybody. You need four numbers: the honest cost of the renovation you actually want, the cost of a rebuild on your block, the share of the house you are altering, and the condition of the services. Once the renovation passes sixty per cent of the rebuild, the rebuild deserves a serious look.
Most people never run this. They arrive with a renovation in mind and stay in that lane until the variations make the decision for them. Here is how to do it early, while you still have every option open.
Step one: price the honest renovation, not the optimistic one
The renovation number people carry in their head is almost always the version where nothing goes wrong.
The honest number includes everything the existing house needs to reach the standard of the new work. If you are opening up the kitchen and the wiring is original, the rewire belongs in the number. If the bathroom is being redone and the waterproofing under it has failed, that belongs in the number too. A client in Earlwood thought taking out one wall was the whole job. Because it was load-bearing, it needed an engineer, survey, drawings and a complying development certificate, and moving it meant relocating wiring, patching the floor and reworking the bathroom wall beside it.
This is where budgets move without anyone watching. A wall comes down and the plumbing needs relocating. Waterproofing opens up something that was not in the quote. Each variation is manageable alone. Together they move the budget well past the quote.
Price the version with those included, because that is the version you will actually pay for.
Step two: get a rebuild figure for your block
You cannot compare against a number you do not have, and this is the step people skip because a rebuild feels like a different conversation entirely.
It is not. It is the other half of the same conversation, and you need a real figure for your site, including demolition and approvals, not a general one, because what your block can carry and what it will cost to build on are specific to it.
Step three: work out how much of the house you are actually altering
Here is the shortcut that works without a spreadsheet.
If more than half of your home is being significantly altered, the rebuild conversation belongs on the table. Walk through and count honestly. Not the rooms getting new paint, the rooms getting structurally changed, replumbed, rewired or reconfigured.
People routinely surprise themselves at this step. A project described as a kitchen and bathroom renovation with a small extension can touch two thirds of a house once you look at it properly.
Step four: check the age of the services
Plumbing and electrical have a working life of roughly forty to sixty years. Plenty of older homes around Kogarah are at or past that mark.
If the services are near the end of their life, they are going to be replaced in the next decade whether you plan for it or not. Including that in the renovation column is the honest thing to do, and it often moves the comparison on its own.
Reading the result
Divide the honest renovation cost by the rebuild cost.
Below sixty per cent, and renovation is very likely the right call. Between sixty and eighty per cent, the rebuild deserves a serious look, because at that point you are choosing between a compromised result and an uncompromised one for a similar spend. Above eighty per cent, you are paying rebuild money to keep old foundations, old services and a layout you did not design.
What the numbers do not capture
Two things sit outside the arithmetic.
Genuine period character is worth something real, and a rebuild cannot give it back. If your home has it, weight the renovation column accordingly.
And a home altered in stages rarely flows the way a home designed as a whole does. Rooms that do not connect naturally, proportions slightly off. It does not show on the plans and it is obvious the moment you live in it.
Run the numbers once, properly, at the beginning. If renovation wins you proceed with confidence. If it does not, you have found out at the only point where finding out is still cheap.
If you would like a second set of eyes on your plans, or you are still working out what the right path is for your site, book a free Vision and Feasibility Session or call me directly on 0468 057 127. About an hour, no obligation, just an honest conversation about whether your project makes sense and what it will take to get it right.
This is part of our complete guide to choosing between renovation, extension, and knockdown rebuild for Sydney homes. Read the full guide
