HOW MUCH DOES IT COST TO BUILD A HOUSE?

Every builder gets asked this, and every honest answer starts the same way. Two houses with the same floor area can land a long way apart, because floor area is one of the smaller levers. What follows is what actually moves the number — and none of it can be resolved without looking at your drawings.

We have deliberately not published a cost-per-square-metre table. A single rate hides the very things that decide affordability, and a number quoted without seeing your plans is a guess wearing a suit.

> WHAT ACTUALLY DRIVES THE NUMBER

Finish level

The single biggest lever a client controls. The same floor plan built to an investor spec versus a luxury spec are different buildings financially — kitchens, tapware, glazing and joinery move the most.

Site steepness

Consistently the most under-estimated factor in custom homes. A steep site changes excavation, retaining, access, crane time and how long every trade takes to do the same work.

Build type

New build, extension, renovation or knock-down-rebuild. Working around an existing structure is slower per square metre than building new, and only new works should be priced.

Size and shape

Floor area drives the headline, but the perimeter-to-area ratio drives the envelope. A long thin plan costs more per square metre than a compact one with the same floor area.

Region

Labour availability, freight distance and subcontractor depth vary state to state, and the gap is widest on trades with thin local supply.

Performance spec

Airtightness, insulation, glazing and mechanical ventilation. A Passive House envelope is a materially different build to a code-minimum one.

> BY REGION

Labour depth, freight distance, climate spec and site character all vary. Pick your region for what matters locally:

• Cost to build in Tasmania
• Cost to build in Victoria
• Cost to build in New South Wales
• Cost to build in Queensland
• Cost to build in Western Australia
• Cost to build in South Australia
• Cost to build in the ACT
• Cost to build in New Zealand

The Northern Territory is not listed. We would rather say so than publish guidance we cannot stand behind.

> COMMON QUESTIONS

How much does it cost to build a house in Australia?

There is no single number, and any figure quoted without seeing your plans is a guess. The same floor area can differ enormously depending on finish level, how steep the site is, whether it is a new build or an extension, and where in the country it is. The honest answer comes from pricing your actual drawings.

What is the biggest thing that changes the cost?

Finish level and site steepness. Finish level is the lever a client controls — kitchens, tapware, glazing and joinery move the number most. Site steepness is the one most often under-estimated, because it slows every trade down, not just the excavation.

Is a cost per square metre reliable?

As a sanity check, sometimes. As a budget, no. A per-square-metre rate hides finish level, site conditions, plan shape and spec — the exact things that decide whether a project is affordable. Two houses with identical floor areas routinely land a long way apart.

How do I get a number for my own plans?

Upload them. Wundermator reads architectural PDFs, applies your build type, finish level and site steepness, and returns an indicative cost broken down by category in about 10 minutes.

Is the result a quote?

No. It is an indicative budget estimate for checking a design against a budget — not a builder's formal quote, and not a quantity surveyor's report. Always verify before committing.