Financing a Granny Flat: How Granny Flat Finance Works in Australia

Granny flat finance usually means borrowing against the equity in your existing home rather than taking out a separate loan for the granny flat on its own. Because a granny flat is a secondary dwelling on land you already own, most owners fund the build by increasing their current home loan, refinancing, or using a construction loan that releases money in stages as the build progresses. How much you can borrow, and which path suits you, depends on your circumstances and your lender’s criteria, so treat the detail below as a general guide rather than advice for your situation.

This article explains how to finance a granny flat in plain terms: the main funding options, how a granny flat construction loan releases money as the build happens, the deposit and equity that lenders look for, the difference between fixed and variable rates, the costs to plan for, and the questions to ask before you commit. If you would rather talk it through, the team at Finance Lab can walk you through your options against the construction home loans we work with.

How to finance a granny flat

Most people fund a granny flat in one of three ways, and the right one depends on how much equity you hold and how the build is structured.

The first option is to use the equity in your home. Equity is the value of your home minus what you still owe on it. If your home has grown in value, or you have paid down a good part of the loan, you may be able to borrow against that equity to cover the build. The catch is that if you have less than 20 per cent equity after the increase, you might have to pay lenders mortgage insurance, which can add to the cost of borrowing.

The second option is refinancing your home loan to a larger amount that includes the granny flat build. Switching loans can come with its own costs, including a break fee if you are on a fixed loan, a discharge or termination fee on the old loan, an application fee on the new one, and possibly lenders mortgage insurance. It is worth comparing the full cost before you switch, not just the headline rate.

The third option is a granny flat construction loan, which is designed for building work and releases the money in stages rather than as one lump sum. This is often the cleanest path when the granny flat is a standalone build with a fixed-price contract. Construction loan first home buyer

How a granny flat construction loan works

A construction loan is built for building. Instead of handing over the full amount at the start, the lender releases the funds in instalments that line up with the stages of the build, and pays the builder after each stage is finished and, in most cases, inspected.

A typical build runs through recognised stages, and the loan is drawn down across them.

During the build you generally make interest-only repayments, which means your repayments only cover interest on the amount drawn so far, so your debt is not reduced during that period. Because you only pay interest on what has been released, repayments start small and grow as more of the loan is drawn. At the end of the interest-only period the loan usually changes to a principal and interest loan, where you make regular repayments on the amount borrowed plus interest on that amount, and repayments become higher.

Deposit, equity and how much you can borrow

For a granny flat, the deposit conversation is really an equity conversation, because you are usually borrowing against a home you already own. The 20 per cent mark is the one to know. If you keep at least 20 per cent equity in the property after the build is funded, you can generally avoid lenders mortgage insurance. If your equity falls below 20 per cent, lenders mortgage insurance may apply, and it protects the lender, not you.

How much a lender will advance also depends on your borrowing capacity, which is their assessment of what you can comfortably repay based on your income, expenses and other debts. The added rent or family benefit a granny flat might bring is not guaranteed to be counted, and whether it is depends on the lender. The amount you can borrow depends on your circumstances and your lender’s criteria. Borrowing power first home buyer

A calculator can give you a rough idea before you talk to anyone. Try the borrowing power calculator to see an estimate of what you may be able to borrow first.

Fixed or variable rate

Your granny flat finance will sit on either a fixed or a variable interest rate, and the choice shapes your repayments.

Some borrowers split the loan so part is fixed and part is variable. There is no single right answer, and the better fit depends on your circumstances and how much certainty you want.

When you compare loans, look at the comparison rate, not just the advertised rate. The comparison rate is a single figure of the cost of the loan that includes the interest rate and most fees, so it gives you a fairer like-for-like view across lenders. Comparison rate explained

Costs to plan for

Beyond the build itself, granny flat finance carries costs that are easy to overlook. Application fees are a one-off payment when starting a loan, also called an establishment, up-front or set-up fee. Ongoing fees are charged every month or year for administering the loan. If you refinance to fund the build, you may also face a break fee, a discharge fee and possibly lenders mortgage insurance.

Features can work in your favour too. Offset accounts, redraw facilities and lines of credit are ways of putting extra money into your loan to reduce the amount of interest you pay, which can help once the build is done and repayments move to principal and interest. Whether these features suit you depends on how you manage your money and what your lender offers.

What to do before you commit

A granny flat is a sizeable build, so a little planning up front goes a long way.

Frequently asked questions

Talk it through with the team at Finance Lab

Financing a granny flat is rarely one-size-fits-all, and the cheapest path on paper is not always the right one for your situation. The team at Finance Lab can compare your options across lenders and explain what each one may mean for you.