Who ends up with a build funding gap
- Owners whose builder has issued a large variation or a price increase
- Buyers whose provisional sums came in above the contract allowance
- People hit by site costs such as rock, drainage or retaining
- Borrowers whose completion date has slipped and holding costs are climbing
- Anyone who suspects the approved loan will not cover the final stages
Where a construction loan cost overrun usually starts
A construction loan cost overrun usually comes from a short list of causes. Knowing them helps you decide what to fund and what to challenge.
- Variations: changes to plans, fittings or inclusions after the contract is signed
- Provisional sums and prime cost items: allowances that turn out lower than the real price
- Site conditions: rock, poor soil, drainage or retaining not fully priced at contract
- Price rises and delays: contract escalation clauses and extra holding costs while the build stalls
- Authority conditions: council, utility or certifier requirements that appear after approval
Check your contract for how each of these is handled. If you have not signed yet, our pages on first home buyer construction loans and how construction loans work cover the basics.
Your options when the approved loan is not enough
If you need build over budget finance, there is no single fix. Which option applies depends on your lender, your equity and how far the build has progressed.
Use your own funds
If you have savings, paying the extra directly to the builder is the simplest route. Keep records and tell your lender about the change.
Ask your lender to approve the variation
Lenders usually need to approve changes to the contract, plans or payment schedule. Depending on the change, they may want a fresh valuation, and an increase in the loan amount is not guaranteed. Policy on variations funding construction loan top-ups differs between lenders, so ask early.
Top-up or second lender
A second loan can fund the gap, but it involves the first lender's consent, security arrangements and its own assessment. Costs and timing vary.
Equity in another property
If you own another property, its equity may be usable as additional security or as a source of funds. That adds risk to the second property, so we model it carefully.
Refinancing mid-build
Occasionally borrowers move the whole construction loan to a different lender. It is not always possible, and it is usually a last resort. Our page on non-bank construction loans covers specialist options.
Before you sign a variation
- Get the price, the reason and the effect on the completion date in writing
- Ask whether it changes the progress payment schedule; see progress payments in NSW
- Check how you will fund it before the next stage claim falls due
- Tell your lender and your broker before work starts, not after
- Re-run your repayments with our home loan calculators
Borrowers who plan for a possible construction loan cost overrun before the build begins are in a stronger position. If you are still at the land stage, read about vacant land loans and knockdown rebuild loans for the budget items that often get missed.
Closing the gap in four steps
Size the shortfall
We total what is owing, what is left to draw and what the builder says is still to come, so you fund the real number.
Talk to your lender first
We help you raise the variation with your current lender and find out what it will approve and what it will not.
Compare funding routes
Own funds, top-up, second lender or equity. We compare the cost, risk and timing of each.
Document and proceed
Written variations, updated payment schedule and lender approval in place before the next stage is claimed.
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Cost overrun questions answered
What happens if I have a construction loan cost overrun?
Will my lender increase my construction loan?
Do I have to tell my lender about variations?
Can I refinance to another lender during construction?
How can I avoid a cost overrun?
Information checked on 1 October 2026. Policies and lender participation may change.
Confirm current policy, eligibility and pricing directly with your chosen provider before applying. Lender policy varies, and your broker will match you to a suitable lender for your situation.
This information is general in nature. Policies vary by lender and change frequently. Confirm current requirements with your chosen provider and seek professional advice.
Get your free Sydney construction shortfall assessment
Share your contract, the approved loan and the extra costs. We will lay out the funding options and their trade-offs.