Second Storey Addition Cost Calculator
Estimate the cost of adding a second storey. It is one of the biggest renovations, the existing structure must carry the new floor, so engineering, strengthening and the disruption of lifting the roof are major costs.
Your second storey addition details
Your estimate sits within the typical range.
A second storey roughly doubles your floor space without extending the footprint, ideal on a small block. But it is complex, the roof is removed, the structure strengthened, and you usually move out during the build.
💰 Ways to save
- Get the structural assessment early, whether the house can carry a second storey shapes the whole budget.
- A partial addition over part of the house costs less than a full second storey.
- Plan the build timing to minimise temporary accommodation, a big hidden cost.
or from $1,626/week over 5 years , indicative finance
How we estimate this
A second storey addition in Australia typically costs around $180,000 to $300,000 in 2026 for an average addition, rising to $450,000 to $600,000 for a large full second storey. Structural strengthening, engineering, a new staircase and temporary accommodation add to that.
Pricing reviewed: November 2026.
Doing more than just second storey addition?
Build a combined estimate across every part of your project in one place.
Pricing reviewed November 2026. Indicative Australian costs, not a quote.
Understanding second storey addition costs in Australia
A second storey addition in Australia typically costs around $180,000 to $300,000 in 2026 for an average addition, rising to $450,000 to $600,000 for a large full second storey. Structural strengthening, engineering, a new staircase and temporary accommodation add to that.
It is one of the most complex renovations because the existing structure must carry the new floor and the roof is removed during the build. Engineering determines whether strengthening is needed, which can be a major hidden cost.
Frequently asked questions
How much does a second storey addition cost in Australia?
Roughly $180,000 to $300,000 for an average addition in 2026, and $450,000 to $600,000 for a large full second storey. Structural strengthening and engineering add more.
Can any house have a second storey added?
Not without assessment, the existing walls and footings must be able to carry the extra load, or be strengthened first. A structural engineer determines this before you can budget accurately.
Are you a renovation builder?
Everyone on this page is working out what second storey addition costs because they are ready to hire. Put your business right beneath the calculator, in your state, so you are who they find. From $50/mo.