I met a bloke at a job in Unanderra a few years back who'd just finished a duplex with another builder. Nice enough build. He was planning to sell one half and keep the other, and he'd been told at the pub that separate titles were "just paperwork at the end."
They weren't. Both halves ran off a single water meter. The stormwater from the front unit crossed under the party wall and discharged through what would have become the neighbour's land. The electricity supply came in once and split inside. None of that is unusual, and none of it is wrong if you're keeping both. It just meant that turning the block into two separate Torrens lots required going back and physically re-servicing a finished house, which cost him more than the subdivision itself.
The lesson isn't complicated. Subdivision is not a thing you do at the end. It's a thing you design for at the start, and the two paths — Torrens and strata — want different buildings.
If you're earlier than this and still working out what a dual occupancy even is, start with what dual occupancy means in NSW. Both that post and dual occupancy designs for Illawarra blocks cover the Torrens-versus-strata question in brief. This one goes properly into the process and what each choice does to you afterwards.
Subdivision is its own approval
First thing worth getting straight: building two dwellings and dividing the land into two ownerships are separate consents. Council approving your duplex says nothing about whether you can split the title.
You can lodge them together, as one development application covering both the dual occupancy and the subdivision, or you can build first and apply to subdivide later. Together is generally cleaner — one assessment, one set of conditions, and, more to the point, you find out whether the subdivision is achievable before you've spent a year building for it. Later gives you flexibility if you're genuinely undecided about selling, and it's the right call if the plan might change.
What I'd avoid is the third option, which is not thinking about it at all and hoping. That's the Unanderra situation.
Whether the duplex itself goes through complying development or a full development application is a separate fork, and one worth understanding early, since a fair few dual occupancies can use the fast path while their subdivision cannot. The state-level policies live with the NSW planning department, and your council's local environmental plan is where minimum lot sizes and any local restrictions on dual occupancy subdivision sit. I'm deliberately not quoting a minimum lot size here, because it varies by council and by zone across the Illawarra and getting it slightly wrong is worse than not saying it. Ask your council or a planner for your specific parcel. It's the single most decisive number in this whole exercise.
Torrens: two lots, two houses, no relationship
Torrens subdivision draws a new boundary through the block and creates two ordinary lots, each with its own title and its own address. Each one behaves like any freestanding house. No shared ownership, no body corporate, no levies, no by-laws. Sell one and the buyer owns land and a building outright.
Buyers prefer it and lenders are comfortable with it, which is why it usually produces the better result at sale. It's also the harder one to get, and it's harder for physical reasons as much as planning ones.
To be genuinely separate, each dwelling wants its own everything. Its own water meter. Its own electrical supply and switchboard, with nothing crossing the new boundary. Its own sewer connection, or at minimum a properly documented arrangement, because a sewer line running from one lot under the other is exactly the sort of thing that turns up in a conveyancer's search and stops a sale. Its own stormwater to a legal discharge point without relying on the neighbour. Own gas if there is any. Own driveway and vehicle access from a public road.
That last one is why corner blocks are so useful for Torrens duplexes, and why some mid-block sites end up with a shared driveway they can't design out.
There's also the party wall to think about, if the two halves are attached. Each new lot can only contain its own dwelling, so where they touch, the arrangement has to be sound both structurally and legally — the wall has to be built and documented so that each side stands on its own lot and neither owner's building depends on the other's goodwill. Attached versus detached is one of the first design decisions on any dual occupancy for exactly this reason, and it's the fork I'd settle before drawing anything. There's more on how that plays out on local blocks in is your block right for a duplex.
Where something genuinely can't be separated, a shared driveway on one lot, a services trench crossing the boundary, an easement gets registered on the titles. That's the instrument attached to the plan of subdivision setting out the rights and the restrictions: who can drive over what, who maintains it, who can dig where. It's normal and it's fine. It's also permanent, so read it.
Strata: one parcel, two lots, one owners corporation
Strata subdivision doesn't divide the land. It divides the building into lots and leaves everything outside those lots as common property, jointly owned by the lot owners through an owners corporation.
That structure comes with machinery. An owners corporation with the two of you in it. By-laws. A strata plan that defines exactly where each lot's boundaries sit, which is often the internal face of the walls rather than the outside of the building. A single insurance policy covering the whole building, held by the owners corporation rather than by each owner. A capital works fund that both owners contribute to. Levies, meetings, minutes, the lot.
With two lots it's manageable, and plenty of people run a two-lot scheme happily for decades. But it is a relationship with your neighbour that Torrens doesn't create. If they won't contribute to the roof, that's a dispute process, not a phone call. If you want to repaint the exterior, that's common property. I've had clients love it, because the shared insurance and maintenance suits an investment pair they own both of, and I've had clients find it maddening the moment they sold one half to a stranger.
The upside is that strata is achievable in places Torrens isn't. Where the block is under the minimum lot size for two Torrens lots, where the design can't give each dwelling independent access, where the services genuinely have to be shared, strata is often the only way to end up with two saleable dwellings. It also allows a much tighter building, because you're not fitting two compliant lots side by side.
Resale is where the difference shows. A strata half of a duplex generally doesn't fetch what a Torrens lot does, and some lenders treat two-lot schemes differently. Not a dealbreaker, just something to price in rather than discover.
How the process actually runs
Assuming you're subdividing after or alongside the build, roughly this order.
A registered surveyor prepares the plan of subdivision — the document that defines the new lots, dimensions, areas, and any easements. For a strata scheme it's a strata plan showing lot boundaries within the building, and it can only be drawn accurately once the building is up, because it's measuring real walls.
Council or your certifier then issues the subdivision certificate, which is the sign-off that the conditions of consent have been met. That's where all the physical separation gets checked: the meters, the connections, the driveways, whatever the consent conditioned. For a strata scheme you'll also need the occupation certificate for the building, since the plan describes a building that has to legally exist.
Then the plan is lodged for registration with NSW Land Registry Services, and when it's registered the new titles issue. That's the moment the lots exist. Not when council approves, not when the surveyor finishes — when the registry registers it. Contracts for sale sometimes get exchanged before registration on a subject-to basis, and if that's your plan your conveyancer needs to be involved well before this point.
There are fees at several stages, a Section 88B instrument if there are easements, and the water authority will want its own certificate confirming the services are in order. I'm not going to guess at the numbers because they change, but the surveyor, the certifier, the registry and the water authority are four separate invoices and none of them are in your building contract.
So which one
If the block comfortably supports two Torrens lots, each with its own street frontage or a workable driveway, and you can service both independently, do that. It's worth more, it's simpler forever after, and the extra design discipline it forces on you tends to produce a better duplex anyway.
If the block is tight, or the access only works as a shared driveway, or the numbers only stack up with a building that's too big for two separate lots, strata is a legitimate outcome rather than a consolation prize. Just go in understanding that you're creating an ongoing relationship between the two owners, and design the building so that relationship has as little to argue about as possible. Separate meters even in a strata scheme. Roofs that can be maintained without crossing into the other half. No shared plant.
And if you're keeping both and never selling, you don't have to subdivide at all. Two dwellings on one title is perfectly normal, it costs you nothing in surveyors and registry fees, and you can subdivide later if the design allowed for it. Which loops back to the point: build as though you might, even if you won't.
The money side of the build itself is in what it costs to build a duplex in NSW, and it's worth reading alongside this, because the subdivision costs sit on top of that number rather than inside it.
We design and build dual occupancies across Wollongong, the Illawarra and the Southern Highlands, and we'll tell you at the sketch stage whether your block is a Torrens candidate or a strata one, because it changes the drawings — that's on our duplex and dual occupancy page. Send the address and a copy of the title through the contact page or call 0434 037 851 and we'll have a look before anything gets drawn.
Want a hand with this at your place? Get a free quote or call 0434 037 851.