Second-storeyadditionsinBrisbane:abuilder'sguide

A well-designed second-storey addition can double the size of a Brisbane home, capture a view, and keep your family in the suburb and on the block they love. It's also one of the most complex jobs a builder takes on — and one where the wrong approach gets expensive fast.

Can your existing home take a second storey?

Three things have to be true:

• The existing slab, footings and walls can carry the additional load (or can be retrofitted to)
• There's a clear vertical path for a staircase that doesn't destroy the ground floor plan
• Roof access, set-downs and weatherproofing during construction are workable

We always start with a structural engineer's report before pricing. We've walked away from second-storey jobs where the existing structure simply couldn't support it economically — and we've recommended a knockdown rebuild instead.

Living in the home during the build

About half our second-storey clients want to stay in the home through the build. It's possible, but the program is longer and the dust is real. We staircase early, deck the roof early, and protect the ground floor with temporary ceilings. For families with young kids or anyone working from home, renting out is usually the better answer.

Design moves that work

The best second-storey additions don't look like additions. They resolve the roof line, repeat the material palette, and integrate the staircase so the ground floor feels reorganised, not just punctured. We work closely with architects on every one of these — it's not a job for a templated approach.

Budget

Expect $7,500 to $10,500 per square metre for a quality second-storey addition in Brisbane in 2026 — higher than a new build because of the structural retrofit and the difficulty of building on top of an occupied home. For a 120m² upper floor with two bedrooms, an ensuite, a master and a study, budget $900K to $1.25M.