How much does it cost to build a duplex?
Here's a comprehensive breakdown of duplex construction costs (2024 figures):
Average Total Costs:
Single-Story Duplex
Basic: $600,000 - $800,000
Mid-range: $800,000 - $1.1M
High-end: $1.1M - $1.5M+
2. Double-Story Duplex
Basic: $800,000 - $1.2M
Mid-range: $1.2M - $1.6M
High-end: $1.6M - $2.2M+
Cost Per Square Metre:
Basic finish: $2,000 - $2,700/m²
Mid-range: $2,700 - $3,500/m²
High-end: $3,500 - $4,500+/m²
Location Cost Variations:
Sydney: +10-15%
Melbourne: +5-10%
Brisbane: Around average
Perth: -5-10%
Regional: -10-20%
Breakdown of Costs:
Pre-Construction
Council fees: $10,000 - $25,000
Design/architectural: $15,000 - $40,000
Engineering: $5,000 - $15,000
Surveyor: $2,000 - $5,000
Soil testing: $1,500 - $3,000
2. Site Preparation
Demolition (if needed): $15,000 - $40,000
Site clearing: $5,000 - $15,000
Earthworks: $10,000 - $30,000
Service connections: $10,000 - $25,000
3. Construction Components
Foundation: 10-15% of build cost
Frame and roof: 15-20%
External walls: 10-15%
Internal finishes: 25-30%
Plumbing/electrical: 15-20%
Kitchen/bathrooms: 10-15%
Additional Costs:
Site-Specific Costs
Retaining walls: $10,000 - $30,000
Sloping block: $20,000 - $100,000
Rock removal: $10,000 - $30,000
Tree removal: $2,000 - $10,000
2. External Works
Driveways: $10,000 - $20,000
Landscaping: $20,000 - $40,000
Fencing: $5,000 - $15,000
Letter boxes: $500 - $2,000
3. Legal/Administrative
Subdivision costs: $20,000 - $40,000
Legal fees: $5,000 - $10,000
Insurance: $3,000 - $8,000
Project management: 5-10% of total cost
Cost-Affecting Factors:
Design Elements
Size of each unit
Number of stories
Roof design
External materials
Internal finishes
Shared walls design
2. Site Conditions
Block size/shape
Soil type
Access issues
Existing structures
Service availability
3. Council Requirements
Zoning restrictions
Setback requirements
Height limitations
Parking requirements
Energy efficiency standards
Money-Saving Strategies:
Planning Phase
Efficient design layout
Standard materials
Mirror image design
Shared services where possible
Simple roof design
2. Construction Phase
Bulk material ordering
Coordinated trade scheduling
Regular site supervision
Clear communication channels
Important Considerations:
Project Timeline
Planning/approval: 4-8 months
Construction: 10-14 months
Total project: 14-24 months
2. Builder Selection
Experience with duplexes
Financial stability
Quality of past projects
References
Insurance coverage
3. Investment Considerations
Rental potential
Resale value
Market demand
Area demographics
Future growth
4. Risk Management
10-15% contingency budget
Detailed contracts
Progress payments
Regular inspections
Weather allowances
Best Approach:
Thorough feasibility study
Multiple builder quotes
Professional design team
Clear contracts
Regular project monitoring
Quality control measures