Granny flat NBN: your own service, or share the house's?

Can a granny flat get its own NBN service? Yes, and this is the whole answer in one place: the two ways a granny flat gets internet, the gate on one of them that nobody warns you about, what cable goes between the buildings, and what to run before the slab if you are still building. It comes from years of granny flat jobs across Sydney, and the rest is a quote from photos and a distance.

Granny flats are a steady part of our work:

• 17%of NBN installation enquiries were for a granny flat137 of 825 enquiries where the property type was known
• 18%of NBN conduit enquiries were for a granny flat123 of 685 enquiries where the property type was known
• 20%of data cabling enquiries were for a granny flat106 of 537 enquiries where the property type was known

Two roads: share the house’s service, or get the flat its own

Choose first, because everything else follows from it.

• Share the house’s service. One bill, the house’s provider, a cable between the buildings and a second router in the flat with its own name and password so the tenant’s WiFi is theirs. No new account, and nothing to register. One job that did exactly that shows how the run goes in.
• A separate service for the flat. Its own bill and its own provider, which starts with your provider asking nbn for an additional connection, and then its own NBN connection. Most people do not know that road has a gate until a provider says “missing address”.

Renting the flat? Sharing is the road that does not need the landlord to register anything; ask the owner whether the cable can go in.

Which road suits the flat?

Its own NBN service Share the house's connection

StreetPitMain houseYardGranny flat 121

A separate service for the flat

Its own bill and its own provider, which starts with your provider asking nbn for an additional connection. Where NBN runs a second lead-in from the street, the conduit on the property goes in to their spec, then the inside run.

1. 1Ask your provider to add the flat
2. 2Lay the conduit before the slab

Share the house's service

One bill, the house's provider, a cable between the buildings and a second router in the flat with its own name and password. Gel-filled underground cable, in conduit.

1. 1Lay the conduit before the slab

The address is the gate

Here’s the gate nobody warns you about. nbn links every connection to a unique address, so a granny flat that shares the house’s street address can’t simply be ordered like a new home. A provider can only order a service for an address that is in NBN’s database, and the flat usually isn’t there. That’s straight from nbn’s own guidance on granny flats (opens in a new tab).

The way in is your phone and internet provider, not the council. nbn says a granny flat that shares the house’s address is connected through an “additional connections process”, and your provider is the one who asks nbn for it. Ring them, say you want an additional connection for a secondary dwelling, and have two things ready: the flat’s coordinates (drop a pin on your phone’s map) and proof the flat is occupied, such as a lease or a utility bill. nbn says the provider may ask for both. It can take weeks, sometimes longer, so start before the tenant moves in.

If the flat has its own street address, say 12A, and it still isn’t in NBN’s address checker, it’s the same call: your provider lodges it with nbn as a missing address (opens in a new tab). The council’s part is only the address itself. It allocates street numbers, so if you want the flat to have its own, ask the council, ideally before you build.

Subdividing is a different process. nbn treats a new lot as a new development, not a granny flat. Whether to subdivide is a question for the council and a planner, not for a cabler.

Whichever road you take, talk to your provider before any work starts, because nbn says an extra service may cost extra or come with its own requirements. And all the cabling on your side, between the buildings and inside the flat, has to be done by a registered cabler working to nbn’s standards. That’s the part we do.

If the house is on FTTP, the box carries more than one service

The NBN box on a house with fibre to the premises has more than one data port. A separate service for the flat can come from the house’s own box over a cable, with no second lead-in from the street; the flat still needs nbn to add it, through your provider, for its own bill, but the trench to the street is not part of the job. What the box is and how its ports work is in our guide to the NBN connection box. If the house is upgrading to fibre, do the flat’s cable at the same time: FTTP upgrade cabling.

If the house is on HFC, the right cable is coax, not ethernet

On a coax network a separate service for the flat needs a coax run and its own socket in the flat, not an ethernet cable. If the walls are still open, run both kinds so either road works later. A builder who ran ethernet where the coax network needed coax is one of the commonest things we find.

Sharing the house’s service: the cable between the buildings

Every granny flat job starts with two questions: how far the flat is from the house, and what is between them: grass, garden or concrete. Those two decide the job. The cable has to be rated for the yard: gel-filled underground ethernet in conduit, at the depth the nbn lead-in guide requires, never internal blue cable in a wet pipe, which fails within a few years. A socket at each end, and a second router in the flat with its own name and password, the same way a wired network in the house is put together.

The trench is the cost. On grass, the customer can dig it and we lay the conduit and the cable; on concrete it is cut and patched, or the run goes another way. The conduit itself is the NBN conduit installation page, and the cable and sockets are ordinary data cabling: you can price the run with our data cabling estimator.

An extender rarely reaches. A bridge does.

The extender in the back window is the thing nearly everyone has already tried, and it rarely crosses a yard. Mesh sometimes does: a unit in the back window of the house and one in the flat’s window facing it, and it is the renter’s option because nothing is dug or drilled. Where the distance or the concrete beats mesh, a wireless bridge, two small dishes on the roofs facing each other, carries the connection across without a trench. The WiFi Technician page has the four fixes in order of cost.

The cable that is already there

Pull the socket off in the flat and look. Old two-pair phone cable cannot carry internet, whatever socket is on it. Blue eight-wire cable can, and if it ends at the box on the house’s outside wall with nobody having joined it inside, the job is joining it, not trenching. Photos of both ends tell us which. If the house’s box has moved since the cable was run and the cable now ends in the wrong place, that is the NBN box relocation page’s territory.

Building the flat: conduit before the slab, your provider before the tenant

If the flat is at the frame stage, this is the cheapest moment you will ever have. A conduit between the buildings while the trench is open, both cable types through it if the house is on coax, a socket where the router will go, the NBN box’s place chosen before the plaster if the flat is getting its own service, and a call to your provider about an additional connection before the tenant moves in, so the flat is in NBN’s database by the time they do. If you want the flat to have its own street number, ask the council while you are building.

When nbn won’t add the flat

If nbn won’t add the flat, or the wait is longer than the tenant can go without, two roads stay open. Share the house’s service over the cable above. Or a 5G home internet plan from any carrier, a modem plugged into power in the flat, no cabling at all. When a trench isn’t possible and the address isn’t coming, that’s what we recommend, even though it means there’s no job for us.

A phone line in the flat

On the NBN the phone runs through the router, so a phone in the flat is a phone port off the shared router, cabled down to the flat, or a phone-only plan on a mobile network. Never a new copper line; there are none.

What we actually do, by road

Sharing the house’s service: gel-filled cable in conduit between the buildings, a socket at each end, a second router in the flat, tested. Or make the existing cable work: terminate it, join it inside, test it. Or a wireless bridge where the yard cannot be dug, or mesh where the distance allows.

A separate service: once the address exists, the cable from the house’s FTTP box to the flat and a socket there; or for a coax network, the coax run and socket; or, where NBN runs a second lead-in from the street, the conduit on the property to their spec and the inside run. Whether NBN’s installer runs a second lead-in depends who turns up, and the conduit page says whose part the pit is.

Building: the conduit before the slab, the inside cabling before the plaster, the sockets at handover.

Every version is quoted from photos and a distance where the job allows, and the quote comes as two options, share or separate, so you choose on price and on who pays the bill. The quote form and what it costs to quote are at the end of this post. A shared cable that worked for years and has stopped is a fault, and the NBN Technician page is where that books.

What a granny flat connection costs, and what moves the price, explained on camera:

Questions people ask about granny flat NBN

Why won’t any provider connect my granny flat?

Because the flat isn’t in NBN’s database, and nbn links each connection to a unique address. A flat that shares the house’s address goes through nbn’s additional connections process instead, and your provider is the one who asks for it.

How do I get the granny flat’s address registered with NBN?

Through your phone and internet provider, not the council. Ask for an additional connection for a secondary dwelling, or a missing address request if the flat has its own street number. Have the flat’s coordinates and proof it’s occupied ready, because nbn says the provider may ask for both. It can take weeks, sometimes longer.

The land isn’t subdivided. Can I still get a separate service?

Usually, yes. A flat that shares the house’s address can still be connected through nbn’s additional connections process; your provider requests it. If you are subdividing, nbn handles it as a new development instead, and that starts with the council.

Can I share the house’s NBN with the flat instead?

Yes, and it is the road with no gate: one bill, a cable between the buildings, a second router in the flat with its own name and password. On FTTP the house’s box has spare ports, so the flat can have its own service over the same cable once its address exists.

What cable goes between the house and the granny flat?

Gel-filled underground ethernet in conduit, for sharing or for a separate service off an FTTP box; coax, for a separate service on a coax network; both, if the walls are still open. Never internal blue cable in a wet pipe.

Who’s allowed to run the cable to the granny flat?

A registered cabler, working to nbn’s standards. nbn’s own guidance says all customer cabling has to be done that way, whether you are sharing the house’s service or the flat has its own.

The builder ran a cable but nobody connected it. What now?

Photos of both ends. If it is eight-wire ethernet ending at the house’s outside box, it is joined inside and tested, and that is the whole job. If it is old phone cable, it cannot carry internet and a new run goes in beside it.

Can a wifi extender or a mesh reach the granny flat?

An extender rarely does. Mesh sometimes does, with a unit in the back window of the house and one in the flat’s window. Where the distance or the concrete beats mesh, a wireless bridge carries the connection across without a trench.

We’re at the frame stage. What should go in now?

A conduit between the buildings while the trench is open, both cable types through it on a coax network, a socket where the router will go, and a call to your provider about an additional connection before the tenant moves in.

What if nbn won’t add the flat at all?

Share the house’s service over a cable, or put a 5G home internet plan in the flat. Both are what we recommend when the flat is not coming onto nbn.

Can the granny flat have its own phone line?

A phone port off the shared router, cabled down, or a phone-only plan on a mobile network. Not a new copper line.

A real job from the field

Mount Druitt, a house with a granny flat behind it, on HFC. The owner at the front had two services, one for the home and one for a business, and gave up the home service so the granny flat could have its own.

Both services turned out to be running off the one aerial lead-in. At the box on the outside wall the lead-in split two ways, one leg to the socket inside the house and the newer leg for the flat. Unplugging one leg dropped the granny flat’s service, and unplugging the other dropped the business service, which is the test that shows two services on one lead-in.

The coaxial run to the flat went through the conduit that already carried the Cat5 between the buildings. The video describes that pull rather than showing it, so this is as far as the page goes.