How Much Does a Home Extension Cost on the Gold Coast? (2026 Guide)

An extension is the biggest home project most Gold Coast families ever take on, and the cost question deserves a straight answer. Extension pricing comes down to the size, whether you build out or up, and how much of the existing house the new work has to touch. Here's how budgets tend to break down in 2026.

Indicative cost ranges

• Single-storey extension (building out): commonly around $2,500–$4,500 per square metre, so a modest 20m² bedroom or living addition often lands roughly in the $50,000–$90,000 range, and a larger 40m² family-room extension in the $100,000–$180,000 range.
• Second-storey addition (building up): typically $3,500–$5,500+ per square metre — the existing roof comes off, the structure below often needs strengthening, and stairs claim space on both levels.
• Wet areas multiply cost. Adding a bathroom, ensuite or kitchen inside the new space adds plumbing, waterproofing and fit-out well beyond the base rate.

What moves the number most

• Out vs up. Building out is usually cheaper per square metre — if your block has the room and setbacks allow it.
• Ground conditions and slope. Sloping Gold Coast blocks, poor soil and rock all add foundation cost before a single wall goes up.
• Matching the existing home. Tying rooflines, cladding and floors into the original house so the join disappears is skilled work — it's also the difference between an extension that adds value and one that looks bolted on.
• Approvals and engineering. Home extensions generally require building approval — as a rough planning allowance, certifier fees, drawings and engineering commonly run $5,000–$15,000 depending on complexity, though only a private building certifier can confirm what your project needs. Our approvals guide explains how the process works in Queensland.
• Living through the build. Most families stay in the home during an extension. Staging the work to keep the house liveable takes planning, but it beats months of rent.

Extension or move?

The honest comparison isn't extension cost vs nothing — it's extension cost vs the full cost of moving: agent fees, stamp duty, removalists and the compromise of someone else's floor plan. For families settled in a school zone or a street they love, a well-built extension is often the cheaper path to the home they actually want. The caveat is over-capitalising: the smartest extensions match the quality tier of the street, and we're upfront with clients about where that line sits.

Where never to cut corners

Structure, footings, waterproofing and the roof tie-in. A cheap extension that leaks at the junction or moves on poor footings costs far more to fix than it saved. We build extensions to be indistinguishable from the original home — structurally and visually — and coordinate licensed trades and certifiers so compliance is never in question.

Get a real number for your extension

Tell us what you're imagining — even a rough sketch and a few photos of the house. We'll walk the site, talk through what's feasible, flag the approval requirements early and give you a free, itemised quote for your home extension, with every stage in writing.