Duplex Construction Sydney & NSW

State Property Development builds duplexes and dual occupancy developments across Greater Sydney. NSW Builders Licence 355555C. $20M public liability. HIA Member 1269991. Duplex construction is a core part of our residential work, with completed projects visible on our Projects page including builds at Constitution Hill, Concord, and North Ryde.

A duplex is two separate dwellings on one lot, typically built to be Torrens title subdivided into two independently owned properties once construction is complete. This makes duplex construction attractive for owner-occupiers wanting to live in one dwelling and sell or rent the other, and for developers building for sale.

What’s Involved in Duplex Construction

• Design and construct, or construction from your approved drawings
• Dual occupancy DA or CDC approval management
• Shared or separate services design – power, water, sewer connections for each dwelling
• Fire separation between dwellings to NCC requirements
• Torrens title subdivision coordination once construction is substantially complete
• Site works – driveways, landscaping, and fencing for both dwellings

Duplex Construction Costs in Sydney

The cost of building a duplex in Sydney can vary significantly depending on the size of each dwelling, architectural design, structural requirements, site conditions, access, selected finishes and the overall scope of works.

A standard duplex development will generally include two separate dwellings, with the final construction cost influenced by factors such as:

• Total floor area of each dwelling
• Number of bedrooms, bathrooms and living areas
• Single-storey or double-storey design
• Structural engineering requirements
• Site slope, soil conditions and excavation
• Stormwater and hydraulic requirements
• Driveways, retaining walls and external works
• Kitchens, bathrooms, joinery and finishes
• BASIX, NatHERS and energy-efficiency requirements
• Council, certifier and authority requirements
• Demolition, service connections and site access

Larger duplexes, premium specifications and architecturally designed developments are assessed and priced individually based on the completed plans, engineering documentation, specifications and inclusions.

State Property Development provides tailored preliminary estimates for duplex construction projects across Sydney and NSW. To receive an indicative assessment, submit your plans and project information through our Free Preliminary Building Estimate form.

Approval Pathway

Dual occupancy development in NSW requires either a Development Application (DA) or, where the site meets specific criteria under the NSW Low Rise Housing Diversity Code, a Complying Development Certificate (CDC). The CDC pathway is faster but has strict eligibility requirements around lot size, width, and zoning. We assess your site against CDC criteria before recommending a pathway.

Torrens title subdivision – splitting the duplex into two separately titled and separately saleable properties – requires a separate subdivision application, typically lodged once construction is substantially complete. We coordinate with your surveyor on subdivision timing so it doesn’t delay your ability to sell or settle either dwelling.

Real Duplex Projects

We’ve completed duplex construction across Sydney, including builds at Constitution Hill, Concord (2 Tripod St), and North Ryde. Photos of completed and in-progress duplex work are on our Projects page – real builds, not stock photography.

Important: Any preliminary estimate is provided as a general guide only. A formal construction quotation can only be prepared after reviewing the complete architectural plans, structural engineering, hydraulic design, geotechnical report, BASIX or NatHERS documentation, specifications and site conditions.

→ See also: New House Construction Sydney

→ See also: Knockdown Rebuild Sydney