Avoid These 5 Construction Loan Rate Mistakes

Construction loan rates often cost more than standard home loan rates, not because lenders charge a premium on the rate itself, but because you only pay interest on funds as they're drawn down during the build.

If you're planning to build in Glenelg, whether it's a custom home on one of the wider Jetty Road blocks or a knockdown-rebuild closer to the foreshore, understanding how construction finance rates are structured will shape both your upfront budget and your cash flow over the 6 to 12 months it takes to complete your build. The way rates apply during construction is different from a standard mortgage, and that difference changes how you compare offers from different lenders.

Rates Apply Only to Drawn Amounts, Not the Full Loan

You only pay interest on the amount drawn down at each stage of the build. If your total loan amount is $600,000 but only $150,000 has been released for the slab and frame, interest is calculated on $150,000, not the full amount. This is why construction loans don't have the same upfront interest cost as a traditional mortgage, even if the advertised rate looks similar.

Consider a buyer building a two-storey home in Glenelg with a land and construction package. The land settles first, so interest begins on that portion immediately. Once the builder completes the base stage and submits documentation, the lender releases the next progress payment. Interest then applies to the land cost plus that first drawdown. Each subsequent release increases the balance on which interest is charged, but you're never paying interest on money that hasn't left the lender's account yet.

This structure means your repayments increase incrementally rather than starting at the full loan amount. During construction, most borrowers make interest-only repayments, which keeps the monthly cost lower while the property isn't yet habitable. Once the build is complete and the loan converts to a standard mortgage, repayments switch to principal and interest unless you've arranged otherwise.

Variable Rates Dominate Construction Lending

Most lenders only offer variable rates during the construction phase. Fixed rates are rarely available until the loan converts to a standard home loan after completion, because the drawn balance changes with each progress payment and lenders don't want to lock in a rate on an uncertain timeline.

This matters if you were planning to lock in a rate to protect against increases during your build. If rates rise between your first drawdown and your final progress payment, your interest cost will rise too. Some lenders allow you to fix the rate once construction is complete and the loan converts, but during the build itself, you're exposed to rate movements.

We regularly see borrowers assume they can fix a construction loan rate upfront the same way they would with a purchase loan. When they discover that's not an option with most lenders, it changes their timing or their lender choice. A handful of lenders do offer partial fixed rate options on the land component if it's part of a land and construction package, but the construction drawdowns themselves remain variable.

Progressive Drawing Fees Add to the Cost

Lenders charge a fee each time they release funds to your builder, typically between $150 and $400 per drawdown. Over five or six progress payments, these fees add $750 to $2,400 to the overall cost of your construction finance, separate from the interest rate itself.

These aren't interest costs, but they're part of the total expense of using a construction loan. Some lenders cap the number of drawdowns included in their base fee structure, then charge extra if your builder requests more frequent releases. Others charge per inspection regardless of how many stages your build involves. When comparing construction loan options from banks and lenders across Australia, the combination of rate and progressive drawing fees determines the real cost, not the rate alone.

If your builder works on a progress payment schedule with seven stages instead of five, confirm whether your lender will charge extra for those additional releases. The difference in fees between lenders can be significant enough to outweigh a slightly lower interest rate, particularly on smaller loan amounts.

Fixed Price Contracts Lower Your Rate Risk

A fixed price building contract means your builder has agreed to complete the project for a set amount, regardless of cost fluctuations in materials or labour. Lenders prefer this arrangement because it reduces the risk of cost blowouts, and some offer slightly lower rates or more favourable terms when a fixed price contract is in place.

Without a fixed price contract, you're working on a cost plus contract, where the builder charges for actual costs plus a margin. This introduces uncertainty around the final loan amount, which makes lenders more cautious. In practice, most project home builders and larger building companies work on fixed price contracts as standard, but if you're using a custom builder or managing an owner builder arrangement, the contract type will affect both your funding approval and the terms you're offered.

Glenelg's coastal location and the mix of heritage overlays in parts of the suburb can extend council approval timeframes, but once your development application is through and you have a fixed price contract with a registered builder, lenders treat the application as lower risk. That doesn't always translate to a lower rate, but it does increase your likelihood of approval and may reduce the deposit requirement.

Construction Loan Rates Convert After Completion

Once your build is finished and you receive final council approval, the construction loan converts to a standard home loan. At that point, the rate you were paying during construction may change, depending on whether your lender's standard variable rate differs from the construction rate, and whether you choose to fix all or part of the loan.

This conversion happens automatically with most construction to permanent loan products, but the rate that applies post-completion isn't always the same rate you had during the build. Some lenders move you to a higher standard variable rate once the property is complete, particularly if the construction rate was discounted. Others keep you on the same rate structure but remove the interest-only option, switching you to principal and interest repayments.

If you're planning to build in Glenelg and you want certainty around your ongoing repayments after the build, confirm what rate and repayment structure will apply once construction is complete. That's also the point where you can typically access offset accounts, redraw facilities, and other features that aren't usually available during the construction phase. For more detail on ongoing loan structure and features, see our guide to home loans.

The timing of this conversion matters if you're coordinating a sale and build. If you're selling an existing property and building a new one, the gap between selling and moving in will determine how long you're paying interest on both the construction loan and any interim accommodation costs. A longer build timeline increases your holding costs, even if the interest rate itself hasn't changed.

Understanding how construction loan rates apply at each stage of your build, and how they differ from the rate and structure you'll have once the property is complete, shapes both your short-term budget and your long-term borrowing strategy. If you're building in Glenelg and want to compare construction loan options across lenders, or if you're weighing up a land and build loan versus buying an established home, call one of our team or book an appointment at a time that works for you.

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