W O Flatz Construction is a residential building company operating across Auckland since 1993. This article provides current cost ranges for villa renovations, home extensions, and new architectural homes in Auckland, based on projects completed by the team. Costs are stated per square metre of finished floor area and are current for 2026.
Villa renovation costs
A full renovation of an Auckland villa runs between $4,000 and $6,500 per square metre of finished floor area. On a 180 square metre villa, that puts total build costs between $720,000 and $1,170,000. The range is wide because villa condition varies significantly. A villa that has been well-maintained externally but not internally may still have subfloor, electrical, and drainage work required once walls are opened.
Scope also drives the range. A renovation that retains the existing layout, repairs what is found, and upgrades finishes sits toward the lower end. A renovation that reconfigures rooms, extends into a lean-to, adds a second bathroom, and specifies custom joinery sits toward the upper end.
Extension costs
Extensions to existing Auckland homes run between $4,500 and $6,500 per square metre. The higher cost per square metre compared to a standalone new build reflects the work required to tie into an existing structure, match existing levels and weathertightness, and integrate new work with existing services.
A single-storey rear extension of 40 square metres typically costs between $180,000 and $260,000 for the build component. That figure excludes consent fees, design costs, and any remedial work to the existing structure discovered during construction.
New build costs
A new architectural home in Auckland runs between $5,500 and $8,000 per square metre. On a 250 square metre home, that is $1,375,000 to $2,000,000 for construction. Specification drives the range. A home with standard joinery, standard cladding, and standard fitout sits toward the lower end. A home with custom cabinetry, specialist cladding systems, high-specification bathrooms, and extensive glazing sits at the upper end.
Site conditions also affect cost. A flat section with good access costs less to build on than a sloped section that requires a piled or retaining wall foundation system.
Why two quotes can differ by $200,000
On a mid-range Auckland renovation, two quotes from licensed builders can differ by $150,000 to $250,000. The reasons are usually one of four things. The scope was not fully defined before quoting, so each builder has made different assumptions about what is included. One builder has priced a lower specification than the other. One builder carries lower overhead and passes that through in price. Or one builder has underpriced to win the work and plans to recover margin through variations.
To compare quotes accurately, the scope document must be the same for every builder you approach. That means a full set of drawings, a specification schedule, and a clear list of what is included and excluded. Without this, you are comparing different products, not different prices.
What a realistic total project cost looks like
The build cost is not the total project cost. To the build figure, add design and consent fees, which typically run 8 to 15% of build cost for architectural projects, council consent fees, structural engineering, geotechnical reports if required, and temporary accommodation if the project requires you to move out.
On a $900,000 villa renovation, a realistic total project budget allowing for design, consent, contingency, and temporary accommodation is $1,050,000 to $1,150,000. A 10% contingency on top of the build cost is the minimum for a residential renovation. On an older villa with unknown subfloor and services condition, 15% is more appropriate.
W O Flatz Construction provides fixed-price contracts for residential work across Auckland. Contact the team to discuss your project scope and get an accurate cost picture before committing to a budget.