Single Storey Extension Cost: What to Budget for in 2026

They’re often simpler to get approved. Understanding your budget helps you make the right choice for your property and your finances.

Single Storey Extension Cost in London: Price Breakdown

Costs vary significantly by location and specific circumstances. London is more expensive than other regions. Understanding what drives costs helps you understand your budget.

In central London, single storey extensions cost 2,000 to 2,800 per square meter. For a 30-square-meter extension, construction might cost 60000 to 84000. Add professional fees at 10 to 15 percent. Add contingency at 10 percent. Total project cost probably runs 78000 to 107000.

In outer London, costs are moderately lower. Typically 1800 to 2400 per square meter. For a 30 square meter extension, total project cost might run 68000 to 92000.

Outside London entirely, costs drop further. South East regions typically cost 1400 to 2000 per square meter. Midlands typically 1200 to 1800. Northern regions typically 1100 to 1600.

For a 30 square meter extension in the North, total project cost might run 42000 to 62000. Significant savings compared to London.

What Affects Single Storey Extension Price

Existing building condition affects cost. Properties in good condition cost less. Buildings with complications cost more. Asbestos or hazardous materials add significant cost.

Design complexity affects pricing. Simple rectangular extensions cost less. Complex shapes with multiple angles cost more. Unusual proportions cost more.

Material choices matter. Budget materials cost less. Premium materials cost more. Matching existing London brick costs more than standard brick.

Finish quality affects cost. Budget finishes cost less. Mid-range finishes are typical. Premium finishes add 20-30%.

Planning permission complexity affects cost and timeline. Simple approvals happen faster and cheaper.

Single Storey Extension Cost Breakdown: Where Money Goes

Structure and framing cost 10000 to 18000. Walls. Load bearing elements. Basic structure.

Roof cost 4000 to 8000. Depends on complexity and materials.

Windows and doors cost between 3,000 and 6,000. Budget windows cheaper. Quality windows cost more.

Electrical and plumbing cost 4000 to 8000. Running new circuits. Running new pipes. Connections.

Insulation and weatherproofing cost 2000 to 4000. Meets Building Regulations requirements.

Internal finishes cost 6000 to 12000. Walls. Flooring. Ceilings. Decoration. Quality affects cost significantly.

Professional fees cost 8000 to 15000. Architecture. Engineering. Building Control.

Contingency (10 percent) is budgeted. Budget surprises happen. Proper planning includes contingency.

Cost Element	Budget Range	Typical Mid-Range	Premium Option	London Factor
Location	Regional	Outer London	Central London	±20-30% variance
Ground Conditions	Good	Mixed	Poor/complicated	±15-20% variance
Design	Simple	Standard	Complex	±10-15% variance
Materials	Budget	Standard quality	Premium	±20-25% variance
Finishes	Basic	Mid-range	Luxury	±25-30% variance
Planning	Permitted Dev	Some revision	Multiple revisions	±10-15% variance
Total Project	£40-60k	£60-85k	£85-120k	Variable by all factors

Single Storey Extension Price: London vs Other Regions

Understanding the differences helps you understand value.

London costs typically run 30 to 40 percent higher than South East. South East costs typically run 20 to 30 percent higher than Midlands. Midlands costs typically run 10 to 15 percent higher than North.

This variation reflects labor, material, and local market costs. London has higher wages. More experienced workers command higher rates. Property values affect overall project economics.

For a 30-square-meter extension, London typically costs 70000 to 95000. South East might be 50000 to 70000. Midlands might be 45000 to 65000. North might be 40000 to 60000.

These are rough ranges. Your specific costs depend on your property and design.

Getting Accurate Single Storey Extension Cost

These estimates are guides. Your actual costs depend on your specific situation.

Get professional assessment specific to your property. A surveyor looks at your property. Your site. Your proposed extension.

Get multiple quotes. Different contractors price differently. Get at least two or three estimates.

Don’t just look at total cost. Understand what’s included. What costs extra. What the timeline is.

Factor in professional fees. Architecture. Engineering. Building Control. These aren’t optional.

Budget contingency. 10 percent set aside for unexpected issues. This isn’t wasted money. It’s insurance.

For single storey extensions, Extension Architecture provides transparent costing. They break down costs clearly. They explain what drives each component. They give you realistic total project costs specific to your property.

A single storey extension is significant. It’s also achievable when you understand costs and plan properly. Get professional guidance specific to your situation.