It’s one of the most common questions vendors sitting on a bigger block face: build the granny flat now, or leave the upside for the buyer.
There’s no single right answer. But there is a right way to work it out, and it has nothing to do with whether you like the idea of a granny flat. It’s an investment decision, not a renovation decision, and it deserves the same scrutiny you’d give any move that affects your sale price and your timeline.
1. Start with what a granny flat actually does for buyer appeal.
A well-built granny flat speaks to two different buyers at once. Investors see a second income stream on one title. Owner-occupiers see space for a parent, an adult child, or a home office that pays for itself if circumstances change. That dual appeal is what tends to lift a property’s buyer pool, not the flat itself.
2. The build has to earn its place in your campaign, not just your block.
A compliant granny flat takes time, council or complying development approval, and capital. Before committing to any of it, the question isn’t “will this add value.” Almost anything liveable adds some value. The real question is whether the uplift in sale price, weighed against the build cost, the time added to your campaign, and the holding costs while it’s underway, genuinely outperforms selling as-is and letting the next owner capture that upside themselves.
3. Building before you sell suits a specific set of vendors.
It tends to make sense when you have enough runway before you need to list, when the numbers clearly support it, and when you’d rather sell a finished, income-producing asset than ask a buyer to take on a project. It rarely makes sense as a last-minute addition squeezed in before a campaign date.
4. Letting the buyer build it themselves suits everyone else.
Many buyers, particularly investors, want to run their own numbers and choose their own builder. If your timeline is tight, or the uplift doesn’t clearly clear the cost and holding period, the better move is often to sell the potential rather than the finished product, and price accordingly.
5. Get the numbers before you decide either way.
Before committing, get a clear, property-specific view: what the site can support, what a buyer would realistically pay for that potential versus a finished dual-occupancy setup, and what the build actually costs to do properly. A quantity surveyor or builder can price the works, and a local agent can advise on how buyers in your area are actually valuing that potential right now.
Selling the full potential
A granny flat can be a smart move before you sell, or an unnecessary one. The difference is whether the decision is based on a proper look at your specific property, or a general feeling that “more space” must mean “more money.” One of those approaches protects your outcome. The other is a gamble with your own capital.
Want to know whether your property’s potential is worth building out or worth selling as-is? Get in touch with our team and we’ll help you weigh up the numbers either way.
