Second Storey Addition Cost in Perth (2026)
In Perth a second-storey addition is priced by the new floor area, whether the structure can carry it, and living elsewhere, with double-brick the load factor.
Your second storey addition details
Your estimate sits within the typical range.
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.
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: October 2026.
What a second storey addition costs in Perth
A second-storey addition in Perth is priced on the area of the new upper level, whether the existing home's walls and footings can carry the added load, and the disruption of building over an occupied home, since adding a storey loads a house built as single-storey, so the ground-floor structure and footings usually need checking and strengthening first. The new floor area and that upgrade set the figure, and the roof comes off for the new level.
Perth's common single-storey double-brick home is the load factor, because the ground-floor double-brick walls may carry a second storey well once checked, but the footings under them were sized for one storey and often need underpinning or new footings for the heavier load, and whether the new upper level is also double-brick or a lighter framed construction changes the load it adds. A structural engineer assesses the load path and designs the strengthening. The sandy, stable soils give reasonable footing conditions once sized for the load. The hot, dry summer means the new level needs insulation, and the isolation of the WA market can add lead time for a steel beam or specialist material. The home is usually unliveable during the build, so renting is a real cost, and labour sits near the national average.
A second-storey addition is major structural building work that needs a licensed builder and a structural engineer, with planning and building approval, in Western Australia under WA Building Services, and licensed plumbers and electricians for the upper-level services. For a Perth home, the clearest way to price a second-storey addition is by the new floor area, the structural upgrade and footings to carry it, and living elsewhere, with the double-brick load path the key factor.
Compare against the national picture: Second Storey Addition Cost in Australia →
Second Storey Addition Cost in other cities
Frequently asked questions
How is a second-storey addition priced in Perth?
By the new upper-level floor area, whether the existing structure can carry the added load, and the disruption of building over an occupied home, since adding a storey loads a single-storey house so the ground floor and footings usually need strengthening in Perth.
Does double-brick affect a Perth second storey?
Yes. A single-storey double-brick home's ground-floor walls may carry a second storey well once checked, but the footings were sized for one storey and often need underpinning or new footings for the heavier load in Perth.
Is the new level double-brick too in Perth?
It can be, or lighter framed. Whether the new upper level is also double-brick or a lighter framed construction changes the load it adds, which the structural engineer weighs when designing the strengthening for a Perth second storey.
Do I need approval for a second storey in Perth?
Yes. It is major structural building work needing a licensed builder and a structural engineer, with planning and building approval, in Western Australia under WA Building Services, plus licensed plumbing and wiring.