Most granny flats in NSW are paid for with equity in the main home, through a loan increase, a construction loan or a refinance. A granny flat, called a secondary dwelling in NSW planning, is generally limited to 60 square metres in residential zones and stays on the same title as the house.
| Point | Detail |
|---|---|
| Usual size limit | 60 square metres in residential zones, unless the council plan allows more |
| Approval | Complying development if the State standards are met; otherwise a development application |
| Title | Same lot as the main house; not a separate property to sell |
| Main ways to pay | Equity release, a construction loan or a refinance |
| Rent | Lenders may count part of it, depending on policy |
What counts as a granny flat in NSW?
A secondary dwelling is a self-contained home built with a principal dwelling on the same lot of land. Under the State’s Housing policy, its floor area is generally capped at 60 square metres in residential zones, though some councils’ plans allow more. Because it sits on the same lot, it is valued and financed as part of the property, not as a second property.
Do you need council approval?
Yes, one of two ways. If the design and the lot meet the State’s complying development standards, a council or a private certifier can issue a complying development certificate, which is usually quicker. If not, for example because the lot is too small or in a heritage area, you lodge a development application with the council. Applications go through the NSW Planning Portal.
How can you pay for a granny flat?
| Option | How it works | Suits |
|---|---|---|
| Loan increase or equity release | Borrow against existing equity, paid out as a lump sum | Fixed-price builds and kit homes with clear payment terms |
| Construction loan | Funds paid in stages as the builder completes work | Larger builds paid by progress claims |
| Refinance | Move the whole loan and draw the build funds at the same time | Borrowers who also want a better rate or structure |
The home equity calculator shows how much equity you could use, and construction loans explains progress payments.
How do lenders value a granny flat build?
For a construction loan, the lender values the property on an “as if complete” basis, using the plans and the fixed-price building contract. The loan is then measured against that completed value. A granny flat adds value, but usually not as much as it costs, so do not assume the valuation rises by the build price.
Will a lender count the rent?
Often, in part. Many lenders count a share of the expected rent towards your income, using a lease or a valuer’s rental estimate, and they apply their own shading. Some count none until the flat has been rented for a while. It is one of the policies that varies most between lenders. The rental yield calculator shows what the rent returns on the build cost.
A worked example
A homeowner borrows $180,000 against their home to build a granny flat. At the 6% example rate over 30 years, that adds about $1,079 a month to their repayments. Say the flat then rents for $450 a week. The lender counts part of that rent and the extra repayment, so the effect on borrowing power depends on how much of the rent each lender accepts.
What about tax and land tax?
- Capital gains tax. Renting out part of your home can mean you lose part of the main residence exemption for that part of the property.
- Income tax. The rent is taxable, and related costs may be deductible.
- Land tax. Earning income from part of your home can affect the principal place of residence exemption. Check with Revenue NSW.
Ask your accountant before you build, not after.
Is a granny flat the same as a granny flat interest?
No. A “granny flat interest” is a Centrelink term for a right to live in a home for life, usually given in exchange for assets or money, and it has its own rules for pensions. This article is about the building and how to finance it.
What should you have ready before you apply?
- Approved plans or a complying development certificate.
- A fixed-price building contract with a progress payment schedule.
- The builder’s licence and insurance details.
- A rental estimate if you want the rent counted.
- Your income documents and current loan statements.
For a bigger project, such as a second full dwelling, the duplex and dual occupancy finance page covers the options, and home renovation loans covers smaller works.
Questions people ask
Can you get a home loan for a granny flat?
Yes, usually as an increase to your existing loan, a construction loan or a refinance, secured on the property it sits on.
How big can a granny flat be in NSW?
Generally up to 60 square metres in residential zones under the State’s Housing policy, unless your council’s plan allows more.
Can I sell the granny flat separately?
No. It is on the same lot as the main house and is sold with it.
Charles Touma compares a loan increase, a construction loan and a refinance for your granny flat and finds lenders that count the rent fairly. A free 30-minute call covers your equity and the build. General information only, not planning, tax or credit advice; check the planning rules for your lot with your council or a certifier. Sources: NSW Department of Planning, secondary dwellings and the Housing State Environmental Planning Policy; NSW Planning Portal; ATO, renting out part of your home, checked 17 October 2026. Example figures use the 6% example rate over 30 years.
General information only, not credit, legal or tax advice. Your situation is assessed properly before any recommendation. Government scheme details change; figures are current at the time of writing.
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