House Refurbishment, Extension & Loft Conversion Cost Guide
2026 UK & London Building Cost Estimates
Planning a home extension, loft conversion or full property refurbishment? This guide provides realistic 2026 cost estimates for projects across the UK, including London and the South East where construction costs are typically higher.
At ECO Contractors & Sons, we provide professional building, refurbishment, structural and groundwork services for homeowners looking to improve, extend and modernise their properties.
The prices below are intended as guide estimates only and can vary depending on property condition, access, structural complexity, specification and finish quality.
Typical Project Budget Ranges (2026)
House Refurbishment Projects
- Light cosmetic refurbishment: £15,000 – £40,000+
- Mid-range full refurbishment: £40,000 – £95,000+
- High-end / structural refurbishments: £100,000 – £300,000+
Single-Storey Extensions
- UK average: £1,800 – £3,300 per m²
- London & South East: £3,200 – £4,600 per m²
- Typical project range: £40,000 – £135,000+
Double-Storey Extensions
- Typical UK range: £120,000 – £195,000+
- London premium builds: £180,000 – £290,000+
Loft Conversions
- Velux / rooflight loft: £35,000 – £55,000+
- Dormer loft conversion: £50,000 – £85,000+
- Hip-to-gable or mansard loft: £75,000 – £140,000+
1) House Refurbishment Costs
Refurbishment costs can vary significantly depending on the condition of the property, structural alterations required and the standard of finish desired.
Typical Refurbishment Pricing (2026)
- Painting & cosmetic updates: from £8,000 – £20,000+
- Kitchen replacement & renovation: £12,000 – £45,000+
- Bathroom renovation: £6,000 – £18,000+
- Full house refurbishment (3-bedroom property): £40,000 – £120,000+
- Structural refurbishment projects: quoted individually
Older London properties often require additional structural work, damp treatment, rewiring, plumbing upgrades and insulation improvements.
2) House Extension Costs
Extensions remain one of the most effective ways to increase living space and improve long-term property value.
UK-Wide Extension Costs (2026)
| Extension Type | Typical Cost |
|---|---|
| 20 m² single-storey | £40,000 – £60,000+ |
| 30 m² extension | £60,000 – £90,000+ |
| 50 m² extension | £100,000 – £140,000+ |
| Double-storey extension | £120,000 – £195,000+ |
London & South East Pricing
Construction costs in London and surrounding high-demand areas are typically significantly higher than national averages.
- Standard London build rate: £3,200 – £4,600 per m²
- Premium contemporary builds: £4,500 – £6,000+ per m²
- Typical London single-storey project: £60,000 – £135,000+
- Large double-storey projects: £180,000 – £290,000+
3) Loft Conversion Cost Guide
Loft conversions are a popular way to create additional bedrooms, office space or en-suite accommodation without sacrificing garden space.
- Velux / rooflight loft conversion: £35,000 – £55,000+
- Dormer loft conversion: £50,000 – £85,000+
- Hip-to-gable loft conversion: £65,000 – £110,000+
- Mansard loft conversion: £85,000 – £140,000+
- Loft conversion with en-suite bathroom: additional £6,000 – £20,000+
Final loft conversion costs depend heavily on structural steel requirements, staircase layout, roof alterations, insulation upgrades and planning conditions.
What Is Usually Included in Build Costs?
Most standard construction quotations typically include:
- General labour and materials
- Foundations and structural shell
- Walls, roof and structural steel installation
- Basic electrical and plumbing first-fix works
- VAT (where applicable)
Additional Costs To Budget For
- Architectural drawings
- Structural engineer calculations
- Planning permission fees
- Party wall agreements
- Building control inspections
- Kitchen & bathroom supply costs
- Interior finishes & decoration
- Contingency allowance (recommended 10–15%)
What Factors Increase Construction Costs?
- Location: London and South East labour costs are significantly higher.
- Structural complexity: Steel beams, underpinning and complex foundations increase costs.
- Access restrictions: Limited access properties require additional labour and logistics.
- Premium finishes: Bespoke glazing, luxury kitchens and specialist materials increase budgets.
- Property condition: Older buildings may need rewiring, damp treatment or structural repair.
- Planning requirements: Conservation areas and planning conditions can add complexity.
- Ground conditions: Poor soil, drainage issues and deep foundations affect groundwork costs.
Our Building & Refurbishment Process
- Initial consultation – discuss your ideas, goals and budget.
- Site assessment – inspect the property structure, access and existing conditions.
- Planning & technical review – coordinate structural and design requirements where needed.
- Detailed quotation – clear breakdown of works, specifications and pricing.
- Construction phase – managed building works with ongoing communication throughout.
- Final completion – finishing works, inspections and handover.
ECO Contractors & Sons aim to deliver reliable workmanship, practical project management and professionally completed building work tailored to each client’s property and budget.
House Extension & Refurbishment FAQs
How much does a house extension cost in London in 2026?
Most London extensions range between £3,200 and £4,600 per m², with larger or premium projects exceeding this range.
How long does a typical extension take?
A standard single-storey extension may take around 10–16 weeks, while larger or more complex projects can take several months.
Do I need planning permission?
Some projects fall under permitted development rights, while others require planning approval. This depends on size, location and property type.
Are loft conversions worth it?
Loft conversions can significantly increase usable living space and often add value to the property, particularly in London where space is limited.
Should I budget extra beyond the builder’s quote?
Yes. It is generally recommended to allow an additional 10–20% for contingency, professional fees and specification changes.
Planning a Refurbishment, Extension or Loft Conversion?
Contact ECO Contractors & Sons for professional advice, realistic budgeting guidance and tailored quotations for your project.
Call: 07979 323906 / 0203 524 9727
Email: contractor@ecosons.co.uk
All prices shown are guide estimates only and subject to site survey, specification and market conditions.