Second Storey Addition Gold Coast: Cost & Process Guide

Adding a second storey is one of the biggest decisions a homeowner can make, and one of the hardest to budget for from a standing start. Costs vary enormously depending on your existing home, so here's a realistic starting point, and the factors that actually move the number.

What a second storey addition typically costs

For a typical 80 to 120 square metre second storey addition on the Gold Coast, total project costs generally fall somewhere between $350,000 and $750,000+. That's a wide range, and it's wide for a reason: a second storey addition depends heavily on what's already there.

This figure covers the upper level construction itself plus the work needed to support it, but it can move significantly based on your specific home. Treat it as a planning range, not a quote. The only way to get a genuine number is a proper assessment of your existing structure.

What pushes the cost up or down

• Existing footings and foundations. If your home's existing footings weren't designed to carry a second storey, they'll need to be strengthened or underpinned before anything else can happen. This is one of the biggest cost variables in any second storey project, and it's not something you can tell just by looking at a house.

• Roof structure. Adding a second storey usually means removing and replacing all or part of the existing roof, which affects both cost and how long the ground floor is exposed to the weather during construction.

• Stairs. Where the new staircase goes affects the layout of both floors, and can mean losing space downstairs to gain it upstairs. This is worth resolving early in design, not after construction starts.

• Services relocation. Plumbing, electrical and sometimes air conditioning often need to be extended or rerouted to reach the new level, which typically adds somewhere in the order of 10 to 15 percent to the overall budget.

The process, in general terms

A second storey addition is a form of home extension, and it follows a similar structured path: an initial consultation to understand what's achievable on your home, design and approvals with your designer, engineer and any other consultants, a clear scope and fixed price contract, then construction and completion. Most extensions of this scale take between 4 and 8 months once construction begins, though a second storey addition often sits at the longer end of that range given the structural work involved.

Council and building approvals are also part of this process, and can vary depending on your local council. If you're just starting to think about a second storey addition, it's worth having that conversation with a builder early, before you've locked in a design that may not suit your existing structure.

Start with a proper assessment, not a guess

Every home responds differently to a second storey addition, and the range above exists precisely because so much depends on what's underneath your current roof. Start your enquiry and we'll walk through your home, your goals and what's genuinely achievable before you commit to a design.

Frequently asked questions

How much does a second storey addition cost on the Gold Coast?

For a typical 80 to 120 square metre second storey addition, total project costs generally fall somewhere between $350,000 and $750,000+. It's a wide range because a second storey addition depends heavily on what's already there, so treat it as a planning range rather than a quote.

What pushes the cost of a second storey addition up or down?

The main factors are your home's existing footings and foundations, which may need strengthening or underpinning, the roof structure, usually removed and replaced in part or full, where the new staircase goes, and services relocation such as plumbing and electrical, which typically adds 10 to 15 percent to the overall budget.

How long does a second storey addition take?

Most extensions of this scale take between 4 and 8 months once construction begins, though a second storey addition often sits at the longer end of that range given the structural work involved.

Do I need council approval for a second storey addition?

Council and building approvals are part of the process and can vary depending on your local council, so it's worth having that conversation with a builder early, before you've locked in a design that may not suit your existing structure.