How Much Does a Second Storey Extension Cost in Melbourne?

Second storey extension Melbourne cost varies significantly based on your home’s specific requirements and design choices. Most Melbourne homeowners invest between $150,000 and $400,000 for quality double storey additions.

We at Cameron Construction understand that budget planning represents the foundation of any successful extension project. Understanding the key cost factors helps you make informed decisions about your home’s transformation.

What Does a Second Storey Extension Actually Cost?

Structural Engineering Investment

Structural engineering forms your largest upfront cost, typically ranging from $15,000 to $35,000 for Melbourne second storey projects. You’ll need to find out whether your project requires a planning permit, a building permit, or both, as these permits are required by law. Soil reports add another $2,000 to $4,000. Foundation strengthening often demands $20,000 to $60,000 depending on your home’s age and existing structural integrity. Homes built before 1980 frequently need extensive foundation work, while newer constructions may only require minor reinforcement.

Construction Materials and Labour Expenses

Building materials consume 40 to 50 per cent of your total budget, with timber framing averaging $180 per square metre and steel frame construction reaching $220 per square metre. Labour costs in Melbourne currently sit at $65 to $85 per hour for qualified tradespeople, with project managers adding $8,000 to $15,000 to coordinate multiple trades. Quality roofing materials range from $45 per square metre for Colorbond to $120 per square metre for premium tiles.

Windows and doors typically cost $800 to $2,500 per unit installed (including installation), while electrical and plumbing rough-ins add $12,000 to $18,000 for standard second storey layouts.

Council Permits and Professional Fees

Planning permits through Melbourne councils cost between $1,500 and $4,000, with building permits adding another $3,000 to $8,000 depending on project scope. Architectural drawings and documentation require $8,000 to $18,000 for comprehensive plans that satisfy council requirements. Building surveyor fees range from $2,500 to $5,500 for inspections and compliance certificates, while bushfire assessments in designated areas cost an additional $1,200 to $2,800 (where applicable).

These base costs provide the foundation for your budget, but several key factors can significantly impact your final investment. Understanding these variables helps you plan more accurately and avoid unexpected expenses during construction.

What Drives Your Extension Costs Up

Complex Design Features Add Significant Expense

Architectural complexity directly impacts your budget through increased structural requirements and specialist trades. Cantilevered balconies cost an extra $25,000 to $45,000 due to complex structural calculations and reinforcement needs. Curved walls and custom window configurations push material costs up by 30 to 40 per cent compared to standard rectangular designs.

Multi-level rooflines require additional waterproofing and flashing details, which add $8,000 to $15,000 to your roofing budget. Vaulted ceilings demand engineered timber beams and specialised installation techniques, which increase framing costs by $180 to $280 per square metre. Open-plan designs that span more than six metres need steel beams or laminated veneer lumber, which add $12,000 to $28,000 to structural costs.

Site Access Determines Equipment and Labour Efficiency

Narrow block access forces builders to use smaller equipment and hand-carry materials, which increases labour costs by 25 to 35 per cent. Steep sites in areas like Mount Waverley or Templestowe require crane access for material delivery (adding $3,500 to $8,500 per lift day). Heritage overlays in suburbs such as Hawthorn or Kew mandate specific materials and construction methods, which push costs up by 20 to 30 per cent above standard builds.

Poor soil conditions that geotechnical reports identify address risks to existing buildings and structures from ground movements, which can demand piling or extensive excavation, adding $15,000 to $40,000 to foundation work. Limited street parking forces contractors to book loading zones, which adds $200 to $400 per week in permit fees throughout construction.

Premium Finishes Command Substantial Investment

Your fixture selections create the largest variable in final costs, with premium choices that double or triple baseline estimates. Engineered timber floors range from $85 per square metre for standard grades to $180 per square metre for premium species like spotted gum or blackbutt. Stone benchtops cost $450 to $850 per square metre installed, while laminate alternatives sit at $180 to $320 per square metre.

High-end bathroom fixtures add $8,000 to $18,000 above standard inclusions, with premium tapware alone that costs $800 to $2,200 per set. Custom joinery for built-in wardrobes or study nooks ranges from $1,200 to $2,800 per linear metre (depending on timber species and hardware quality).

Smart cost management strategies can help you control these variables while maintaining quality standards for your extension project.

How Can You Control Extension Costs

Lock Down Design Details Early

Finalise architectural plans before construction starts to prevent costly variations that typically add 15 to 25 per cent to project budgets. Melbourne councils require detailed documentation for planning permits, so invest $12,000 to $18,000 in comprehensive architectural drawings upfront rather than submit basic sketches that need revision. Specify all fixtures, finishes, and fittings during the design phase to avoid prime cost allowances that builders use to shift cost risks to homeowners.

Request fixed-price contracts with detailed material schedules rather than cost-plus arrangements that leave final costs open-ended. Three written quotes from registered builders help you identify realistic market rates and avoid both overpriced and suspiciously low estimates that signal future cost blowouts.

Apply Value Engineering Without Quality Compromise

Strategic material substitutions can reduce costs by 20 to 30 per cent without affecting structural integrity or visual appeal. Hybrid construction that combines brick veneer with timber frame has higher material costs per square metre, but the speed of construction dramatically reduces site labour costs compared to full brick construction while it maintains thermal performance. Laminated veneer lumber beams cost 40 per cent less than steel equivalents for most residential spans while they offer superior insulation properties.

Standard ceiling heights of 2.7 metres reduce framing and cladding materials compared to 3.0 metre heights (saving $180 to $240 per square metre of floor area). Rectangular floor plans minimise waste and reduce labour hours compared to complex shapes with multiple corners and angles.

Time Your Construction Strategically

Schedule construction during autumn or winter months when builder availability increases and material costs typically drop by 8 to 12 per cent compared to spring peak periods. Book your builder six months ahead to secure better rates and avoid the premium pricing that occurs during high-demand periods. Coordinate permit applications to align with council processing times (typically 6 to 12 weeks for standard extensions) to prevent delays that increase holding costs.

Final Thoughts

Second storey extension Melbourne cost typically ranges from $150,000 to $400,000, with most quality projects that settle between $200,000 and $300,000. Your final investment depends on structural requirements, design complexity, site conditions, and finish selections that can shift budgets significantly in either direction. Professional cost estimation prevents the budget blowouts that affect 60 per cent of extension projects across Melbourne.

Detailed architectural plans, comprehensive soil reports, and fixed-price contracts with registered builders protect you from unexpected expenses that derail project timelines and financial plans. Thorough preparation and realistic budget expectations form the foundation of successful extension projects. Quality builders provide transparent estimates that account for all project variables (from permits to premium finishes).

We at Cameron Construction recommend that you start your extension journey with professional guidance and comprehensive cost analysis. Our experience across Melbourne’s councils means we understand the true costs of quality double storey extensions and ground floor additions. Contact Cameron Construction today for professional cost estimation that turns your extension vision into an achievable reality with transparent prices and expert project management from concept to completion.