Cost of Single Story Extensions: Complete Guide

Single storey extensions remain Melbourne’s most popular home renovation choice, with costs varying dramatically based on your specific requirements.

The cost for single story extension projects typically ranges from $2,500 to $4,500 per square metre, though premium finishes can push this higher. We at Cameron Construction see homeowners frequently underestimate the total investment required for their extension dreams.

What Do Single Storey Extensions Actually Cost in Melbourne

Melbourne’s extension market reveals distinct price patterns across different project types. Kitchen and living room extensions average $3,200 to $4,200 per square metre, while basic bedroom additions start from $2,800 per square metre. Bathroom extensions command premium rates of $4,000 to $5,500 per square metre due to complex plumbing and waterproofing requirements. Master bedroom suites with ensuites typically cost $3,800 to $4,800 per square metre.

Melbourne Market Conditions Push Costs Higher

Melbourne’s construction costs rose 1.3% in 2024 according to the Australian Bureau of Statistics, with materials and labour shortages that drive extension prices above national averages. Council permit fees alone range from $705 for projects under $20,000 to $875 for extensions valued between $20,001 and $50,000 in most Melbourne councils. Site access restrictions in established suburbs add $200 to $500 per square metre to construction costs due to crane hire and material transport challenges.

Premium Finishes Transform Your Budget

Standard extension finishes keep costs within the $2,500 to $3,500 range, but premium materials and custom joinery push costs to $5,000+ per square metre. Engineered stone benchtops add $1,200 to $2,000 to kitchen extensions, while custom cabinetry increases costs by 40% compared to standard options. Underfloor heat systems add $150 to $200 per square metre, and high-end bathroom fixtures can double wet area costs. Smart home integration and premium insulation systems contribute an additional $300 to $800 per square metre to the base construction price.

Hidden Costs That Catch Homeowners Off Guard

Most homeowners focus on construction costs but overlook essential extras that can add 20-30% to their budget. Soil reports cost $800 to $1,500 (depending on site complexity), while structural engineer fees range from $2,000 to $5,000 for complex extensions. Temporary accommodation during construction phases can cost $200 to $400 per night, and utility connections for new areas add $1,500 to $3,500 to your total investment.

These cost factors form just one part of your extension budget equation, with site-specific challenges and design complexity that can significantly impact your final investment.

What Does Your Extension Budget Actually Include

Construction and labour costs represent just 60-70% of your total extension investment. The remainder goes to permits, professional fees, and unexpected expenses that Melbourne homeowners consistently underestimate. These additional costs can add $15,000 to $35,000 to a standard 30-square-metre extension project. Planning permits vary based on application type and complexity, with building permits adding another $1,200 to $2,800 based on construction value.

Professional Fees Add 15-20% to Construction Costs

Structural engineers charge $2,000 to $5,000 for most single storey extensions, while surveyors cost $1,800 to $3,200 for standard residential projects. Soil reports cost $800 to $1,500 (site complexity determines the final price), and designers typically charge 8-12% of construction value for comprehensive design services. Energy efficiency assessments required for compliance add $600 to $1,200 to your budget, while colour and material consultations can cost $1,500 to $3,000 for premium finishes.

Utility Connections and Site Preparation Costs

Electrical work can cost $5,000 to $15,000 for new extension areas, while plumbers charge $1,800 to $3,500 for connections (distance from existing services affects pricing). Temporary fences during construction add $800 to $1,500 to your project costs, and skip bin hire throughout the build phase costs $400 to $800 per month. Site access improvements for crane hire and material delivery can add $2,000 to $6,000 to your total investment, particularly in Melbourne’s established suburbs where narrow driveways and overhead power lines create challenges.

These budget components interact with site-specific factors that can dramatically alter your final investment, particularly when your property presents unique challenges or opportunities.

What Drives Your Extension Costs Higher

Site conditions create the biggest cost variations in Melbourne extension projects. Sloping blocks add $300 to $800 per square metre due to additional excavation and retaining wall requirements, while heritage overlays increase costs by 15-25% through mandatory materials and approval processes. Clay soil conditions common across Melbourne’s eastern suburbs require deeper footings that add $2,000 to $8,000 to foundation costs (extension size determines the final amount). Poor drainage adds $3,000 to $6,000 for stormwater management systems, and narrow side access forces crane hire costs from $1,200 to $2,800 for material delivery.

Material Quality Determines Long-Term Value

Engineered timber frames cost 20% more than standard pine but eliminate future warping issues that plague cheaper alternatives. Colorbond steel roofing adds $15 to $25 per square metre over basic materials but provides 50-year warranties compared to 10-year options. Double-glazed windows increase upfront costs by $400 to $800 per square metre but reduce energy bills by 30-40% according to Sustainability Victoria data. Premium insulation systems cost $50 to $80 per square metre extra but meet 6-star energy ratings that standard materials cannot achieve. Homeowners who choose mid-range finishes save 15-20% on construction costs while they maintain resale value through strategic material selections.

Design Complexity Multiplies Construction Time

Open-plan designs with steel beams cost $8,000 to $15,000 more than standard wall configurations but create premium spaces that increase property values significantly. Raked ceilings add 25-30% to roof construction costs while cathedral ceilings require structural modifications that cost $12,000 to $20,000 for standard extensions. Multiple roof lines increase weatherproofing complexity and add $200 to $400 per square metre to construction costs. Custom joinery and built-in storage systems cost 40-60% more than standard options but maximise space efficiency in compact extensions.

Wet Area Additions Command Premium Rates

Bathroom and laundry extensions require waterproofing compliance that adds construction costs based on new Australian Building Codes Board requirements. Plumbers charge premium rates for wet area connections (distance from existing services affects final pricing), while tilers must follow strict Australian Standards for waterproof membranes. Floor waste installation adds $800 to $1,500 per wet area, and exhaust fan ducting through existing structures costs $400 to $800 per installation. Heated towel rails and underfloor heating systems add $200 to $350 per square metre to bathroom extension budgets.

Final Thoughts

Single storey extension costs in Melbourne range from $2,500 to $5,500 per square metre, with materials, site conditions, and design complexity that determine your final investment. Professional fees, permits, and hidden expenses add 20-30% to construction budgets. Accurate planning protects your project success and prevents cost overruns.

Smart budget management requires three detailed quotes from registered builders and contingency funds of 15-20% for unexpected costs. Structural elements and waterproofing deserve priority over cosmetic finishes, as these foundation investments protect long-term value. Early soil reports and utility assessments prevent costly surprises during construction (schedule these before you commit to final budgets).

Melbourne homeowners benefit when they engage experienced extension specialists who understand local council requirements and site challenges. We at Cameron Construction deliver premium home extensions across Melbourne, with our team that handles planning permits, BCA compliance, and construction coordination. Our approach enhances space, function, and property value while we manage your cost for single story extension projects within your budget parameters.