Mortgage or Construction Loan? What's Actually Different.

"I just want to build a house, why can't I use a normal home loan?"

We get some version of this question almost every week, usually from a client who has already found a block of land or signed a building contract before realising standard mortgages weren't built for this. The short answer: a mortgage releases money in one lump sum for a property that already exists, while a construction loan releases money in stages as a property is built. That difference sounds small, but it changes almost everything about how the loan is assessed, drawn down, and repaid.

If you're weighing up a knockdown-rebuild, a land and house package, or a small development, this is the article that should answer your question properly.

The Core Difference: One Lump Sum vs Staged Drawdowns

A standard residential mortgage is straightforward. The bank values the property, approves the loan, and on settlement day hands over the full amount to the seller (or the previous lender, if you're refinancing). From day one, you're paying principal and interest on the whole loan balance.

A construction loan doesn't work like that, because there's nothing to value yet, or only a partially built asset. Instead, the lender approves a total loan amount based on the fixed-price building contract, then releases funds in instalments, known as progress payments or drawdowns, as each stage of the build is completed. A typical residential drawdown schedule looks something like this:

Slab/base: foundations poured
Frame: house frame and roof trusses up
Lock-up: external walls, windows, and doors installed
Fixing: internal fittings, cabinetry, doors
Completion: final fixtures, landscaping, handover, occupation certificate

Before each payment is released, the lender typically sends a Quantity Surveyor to confirm the work matches the claimed stage. This protects the bank (and you) from paying a builder for work that hasn't actually been done.

Crucially, during construction you usually only pay interest on the amount drawn down so far, not the full approved loan. So if your loan is $600,000 but only $150,000 has been drawn at the frame stage, you're paying interest on $150,000, not $600,000. Once the build is complete, the loan typically converts to a standard principal-and-interest mortgage.

Residential Construction vs Land & House Packages

Not every "build" is financed the same way, and this is where clients most often get tripped up.

A client came to us last year who had found a block of land and wanted to build a four-bedroom home with a well-known volume builder. She assumed one loan would cover both. In practice, most lenders treat this as a land loan plus a construction loan, often set up as two components of the same facility. The land settles first, like a normal purchase, and the loan on that portion behaves like a regular mortgage from day one. The construction component then sits alongside it and only starts drawing down once the build begins.

This matters for cash flow. In her case, we structured the land component as principal and interest but negotiated interest-only on the construction component during the build, so she wasn't paying full repayments on a house that didn't exist yet while also renting elsewhere.

A separate client situation illustrates the other common path: a knockdown-rebuild. He already owned his home outright but wanted to demolish and rebuild rather than renovate. Because there was no land purchase involved, the entire loan was a construction facility secured against the existing property, with demolition treated as the first drawdown stage. Lenders generally want to see a fixed-price contract (not a cost-plus contract) for owner-occupier residential construction loans, because a fixed price gives them, and you, cost certainty before a single trade starts on site.

One more nuance: if you're planning to act as your own builder rather than using a licensed builder, that's an owner-builder loan, and it's a much smaller, more cautious lending market. Many mainstream lenders won't touch owner-builder construction at all, or will cap the loan-to-value ratio well below standard limits, because there's no licensed builder's warranty insurance backing the work. Borrowers seeking this type of construction loan most often will require seeking out a solution from a private lender.

Commercial Construction Loans: A Different Risk Profile Entirely

Everything above still sits within residential lending, where the borrower typically lives in or rents out one property. Commercial construction loans, for things like an office fit-out, a retail building, a warehouse, or a childcare centre, are assessed on a fundamentally different basis.

Where a residential lender mostly cares about your income and the fixed building contract, a commercial lender is assessing the feasibility of the project itself. That usually means:

A detailed feasibility study showing projected costs, timeline, and either sale or rental income
Lower maximum loan-to-value ratios, often 60–70% of the "as-if complete" valuation, rather than the 80–95% common in residential lending
Interest rates and fees that reflect commercial risk, generally higher than residential
A requirement for pre-leasing or pre-commitment in some cases, particularly for purpose-built commercial premises

We worked with a client building a small commercial warehouse for his own logistics business. Because the property was purpose-built and there was no tenant lined up (he was occupying it himself), the lender wanted to see his business financials and cash flow forecasts in addition to the build costs, something that never comes up in a standard home construction loan. The approval process took considerably longer than a residential build of similar value, largely because of this extra layer of business risk assessment.

Multi-Unit Developments: Presales, QS Reports, and Specialist Lenders

At the top end of complexity sit multi-unit developments: townhouse projects, small apartment blocks, or subdivisions with multiple dwellings. These rarely go through mainstream residential lenders at all, and instead move into specialist development finance, sometimes through second-tier or private lenders.

The key differences here:

Presale requirements: many lenders want a set percentage of units (commonly 50–100%) sold off-the-plan before they'll fund construction, to reduce their exposure if the finished stock doesn't sell.
Quantity surveyor (QS) reports: rather than a standard valuer, an independent QS assesses the build cost estimates and certifies each drawdown, because the sums of money and complexity are much higher.
GST and structuring: developments are usually run through a company or trust structure for tax and liability reasons, which changes how the loan is assessed compared to an individual borrower.
Higher fees and rates: development finance carries higher establishment fees and interest rates than residential construction lending, reflecting the higher risk of multi-unit projects.

A client group of three business partners came to us wanting to build six townhouses on a single block they already owned. Because there was no presale requirement met initially, we worked with a lender who instead required a higher pre-approved contingency buffer and staged the loan around progressive sales as units were completed, a very different structure from anything available to an individual building one family home.

Which One Do You Actually Need?

If you're buying a home that already exists, a standard mortgage.

If you're building one home, whether on new land or replacing an existing one, a residential construction loan, likely paired with a land loan if the land isn't already owned.

If you're building for business use or with a commercial tenant in mind, a commercial construction loan, with feasibility and pre-leasing requirements attached.

If you're building multiple dwellings to sell or hold as an investment, development finance, with presale and quantity surveyor requirements built in.

The mistake we see most often isn't choosing the wrong type of loan. It's assuming a standard mortgage application process will work for a build, and only discovering the drawdown structure, interest-only period, or presale requirements partway through. Getting the right facility structured from the start saves both time and money once the first slab goes down.