How Much Does a Single Storey Extension Cost?

Single storey extensions remain one of Melbourne’s most popular home improvement investments, with costs varying significantly based on your specific requirements.

Understanding how much does a single storey extension cost helps homeowners make informed decisions about expanding their living space versus relocating to a larger property.

We at Cameron Construction regularly guide Melbourne families through the financial planning process, breaking down the key factors that influence your total project investment.

What Does a Single Storey Extension Actually Cost

Melbourne homeowners face single storey extension costs that range from $2,200 to $3,500 per square metre, with most quality projects settling around $2,800 per square metre according to recent industry data. A typical 40 square metre extension therefore costs between $88,000 and $140,000, though premium finishes and complex designs push costs toward the upper range. The Building and Plumbing Commission regulates Victoria’s building and plumbing industries, protecting the community and empowering building professionals, with extensions involving structural changes, custom joinery, or high-end materials regularly exceeding $3,200 per square metre.

Material Selection Drives Cost Variations

Your material choices create the largest cost variations in single storey extensions. Standard brick veneer construction with basic internal finishes keeps costs at the lower end, while face brick, natural stone, or timber cladding adds $200 to $400 per square metre. Premium floors like solid timber or natural stone increase costs by $150 to $300 per square metre compared to hybrid options. Kitchen and bathroom inclusions within extensions significantly impact budgets, with quality kitchen fit-outs that add $25,000 to $45,000 to project costs.

Extension Costs Beat House Moves

House moves in Melbourne involve stamp duty that averages 4.5% of property value, plus agent fees, conveyance, and relocation costs that total $45,000 to $80,000 for median-priced properties. A well-designed single storey extension typically adds 15% to 20% property value according to Valuer-General Victoria data, which makes extensions financially superior to relocation for most families. Extensions eliminate school zone disruption and neighbourhood changes while they create exactly the space configuration your family needs.

Site Conditions Affect Final Costs

Your property’s specific conditions directly influence extension costs beyond the base per-square-metre rate. Sloped sites require additional foundation work and retaining walls (often $15,000 to $25,000 extra), while poor soil conditions may demand engineered footings. Limited site access that restricts machinery movement can increase labour costs by 10% to 15%, particularly for rear extensions where materials must be carried through existing homes.

What Drives Extension Costs Higher

Extension size creates the foundation of your budget, but complexity multiplies costs exponentially. Simple rectangular additions with standard ceiling heights cost significantly less than L-shaped designs or extensions that require structural modifications to existing homes. Complex rooflines, cathedral ceilings, or integration with heritage features can increase costs by 25% to 40% above basic rectangular extensions. Multi-level floors, custom window configurations, or extensions that require removal of load-bearing walls demand structural engineers who add significant costs to project budgets.

Premium Materials Command Premium Prices

Material selection separates budget extensions from luxury projects more than any other factor. Face brick costs $180 to $220 per square metre compared to $120 to $150 for standard brick veneer, while natural stone cladding reaches $300 to $450 per square metre. Hardwood floors add $200 to $350 per square metre over standard options, and premium kitchen inclusions with stone benchtops and European appliances increase extension costs by $40,000 to $70,000. Windows represent major cost variables, with double-glazed timber frames that cost $1,200 to $1,800 per square metre compared to $600 to $900 for standard aluminium options.

Site Challenges Add Unexpected Expenses

Difficult site access forces manual material transport that increases labour costs by 15% to 20% when machinery cannot reach construction areas. Steep slopes require cut and fill operations plus retaining walls that cost $400 to $600 per linear metre, while poor drainage adds $5,000 to $12,000 for proper stormwater management. Underground services like gas, water, or electrical lines that require relocation can add $8,000 to $18,000 to project budgets. Rock excavation (discovered during foundation work) costs $150 to $250 per cubic metre compared to $45 to $65 for standard soil excavation.

Beyond these construction costs, Melbourne homeowners must budget for various permits, inspections, and potential temporary accommodation expenses that can significantly impact your total investment.

What Hidden Costs Should You Expect

Melbourne’s permit and certification requirements add substantial costs beyond construction budgets that many homeowners underestimate. Planning permit applications through local councils vary in cost, while building permit applications add another $2,500 to $4,200 depending on project value. Building surveyor fees range from $3,500 to $6,500 for typical extensions, covering mandatory inspections at footing, frame, and completion stages. These professional fees represent 4% to 6% of total project costs for most extensions, though complex designs that require multiple permit variations can push certification costs toward $12,000 to $15,000.

Council Fees Vary Across Melbourne

Different Melbourne councils charge varying fees beyond state-mandated amounts, with some councils that add administrative charges increasing total permit costs by $500 to $1,200. Bayside Council charges higher application fees than Boroondara Council for identical extension types, while heritage overlay areas in councils like Stonnington require additional heritage assessments that cost $2,800 to $4,500. Structural engineers provide reports for extensions that affect load-bearing elements at costs of $1,800 to $3,200, while soil reports for foundation design add $800 to $1,400 to pre-construction expenses.

Temporary Accommodation Costs Add Up

Extensions that affect kitchens or main living areas force families into temporary accommodation that significantly impacts project budgets. Short-term rental costs in Melbourne average $450 to $650 per week for family-sized properties near construction sites, while extended hotel stays cost $180 to $280 per night for adequate family accommodation. Kitchen-less periods that last 6 to 12 weeks during extension completion add $3,500 to $8,500 in accommodation costs, plus dining expenses that average $150 to $220 per week for families who avoid takeaway meals.

Smart staging minimises displacement time, though bathroom relocations during extension work often require 3 to 4 weeks of alternative arrangements regardless of construction schedules.

Insurance and Utility Connection Fees

Home insurance policies may require updates when extensions exceed certain thresholds, with premium increases that range from $200 to $600 annually for extended properties. Utility connections for new electrical circuits, plumbing extensions, and gas lines add $2,500 to $4,800 to project costs depending on distance from existing services. Temporary power and water connections during construction cost $800 to $1,400, while skip bin hire for construction waste adds $400 to $800 per month throughout the build period. Experts recommend allocating 10-20% for unexpected costs that can arise from hidden surprises during construction.

Final Thoughts

Melbourne single storey extensions represent a significant investment that typically ranges from $88,000 to $140,000 for standard 40 square metre additions, though premium materials and complex designs push costs beyond $140,000. Property owners who ask how much does a single storey extension cost must consider material selections, site conditions, and permit requirements that collectively determine their final investment. Professional cost estimation proves essential for accurate budgets, as hidden expenses like council permits, temporary accommodation, and site challenges can add 15% to 25% to initial estimates.

Extensions consistently deliver superior financial returns compared to relocation, as they add 15% to 20% property value while they eliminate stamp duty and relocation costs that often exceed $60,000. Melbourne families avoid school zone disruption and neighbourhood changes when they choose extensions over house moves. Extensions create exactly the space configuration your family needs without the stress and expense of property transactions.

Professional contractors who understand Melbourne’s regulations and council requirements help families make informed decisions about their extension investment. We at Cameron Construction provide comprehensive cost assessments that account for all project variables (including site challenges and permit requirements). Accurate budgets from project inception prevent cost overruns and deliver the quality extension your family deserves within realistic financial parameters.