A real-numbers breakdown of what it actually costs to build a duplex in Sydney's west — land, construction, approvals, and holding costs.
The Real Cost of Building a Duplex in Sydney
Building a duplex in Sydney's west is one of the most effective ways to create equity and generate rental income — but the numbers need to stack up. This breakdown uses a real project at 152 Smart St, Fairfield Heights as a case study.
We'll cover every cost element so you can see exactly where the money goes — and where Buildana's advisory service adds value by identifying savings before you start.
Land Acquisition
The site at 152 Smart St, Fairfield Heights was purchased for $950,000. It's a 620sqm R3 Medium Density Residential zoned lot — ideal for a duplex under CDC pathways.
Key land selection factors: • R3 zoning with minimum lot size of 300sqm per dwelling • Regular shape with adequate street frontage • Minimal slope, reducing earthworks costs • Proximity to transport, schools, and shopping
Buildana's site yield analysis confirmed the lot could support two 3-bedroom, 2-bathroom dwellings with double garages.
Design and Approval Costs
• Architectural design (both dwellings): $28,000 • CDC application and certification: $8,500 • Engineering (structural + stormwater): $6,000 • BASIX certificate: $1,200 • Survey and contour plan: $2,800 • Section 68 application: $1,500
Total design and approvals: approximately $48,000
Using CDC instead of DA saved approximately 8–10 weeks and $5,000–$8,000 in additional council and consultant fees.
Construction Costs
Each dwelling is approximately 165sqm (total 330sqm of build area).
• Construction (both dwellings at $2,800/sqm): $924,000 • Site works (demolition, excavation, retaining): $45,000 • Driveways, landscaping, fencing: $38,000 • Service connections (sewer, water, electrical): $22,000
Total construction: approximately $1,029,000
Buildana's value engineering reduced the original construction estimate by $62,000 without compromising design intent or material quality.
Holding Costs and Total Investment
• Stamp duty on land: $38,000 • Legal fees: $3,500 • Interest during construction (10 months): $52,000 • Council contributions: $28,000 • Insurance (construction + public liability): $4,500 • Miscellaneous (utilities, temporary connections): $3,000
Total project cost: approximately $2,156,000
End value (two dwellings at $950,000 each): approximately $1,900,000 Combined rental income: $1,300/week
This project delivered strong rental yield and significant equity uplift on completion — a result typical of well-planned duplex developments in Western Sydney.
Oliver Alameri
Founder and Managing Director of Buildana. Oliver has over 15 years of experience in residential and commercial construction across Western Sydney, with a focus on delivering quality builds and creating value for clients through smart design and rigorous project management.
