Single Storey Extension Cost UK 2026

A single-storey rear extension is the UK's most popular renovation. In 2026, expect £2,000–£2,800 per m² for a standard spec — meaning £40,000–£56,000 for a typical 20 m² rear extension. Add bi-folds, lanterns and a kitchen and £85,000+ is realistic.

Quick answer

Typical UK price range: £35,000–£90,000. Typical time: 10–14 weeks.

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Extension type Single-storey rear Double-storey Side return Wrap-around Kitchen extension Oak frame

Extension floor area (m²)

Region London South East South West Midlands North of England Scotland Wales Northern Ireland

Specification level Basic / standard Mid-range Premium / high-end

Extras

Bi-fold doors £2,500–£6,000 Roof lanterns £1,500–£3,500 Underfloor heating £2,500–£5,000 New kitchen fit £8,000–£25,000 Architect & plans £2,500–£5,000

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Budget Under £5,000 £5,000 – £15,000 £15,000 – £30,000 £30,000 – £60,000 £60,000+ Not sure

Timeline As soon as possible 1 – 3 months 3 – 6 months 6+ months Just researching

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Key points

• £2,000–£2,800/m² for basic spec; £2,400–£3,500/m² mid-range
• Permitted development up to 4 m (detached) or 3 m (terrace/semi)
• Larger Home Extension scheme allows 6–8 m with prior approval
• Typically takes 10–14 weeks on site

Cost breakdown

Item	Low	High
Foundations + groundworks	£6,000	£12,000
Structure (walls, roof, steels)	£14,000	£28,000
Bi-fold doors / glazing	£4,500	£12,000
Roof lantern (if specified)	£2,500	£6,000
Electrics + plumbing	£3,500	£7,000
Plastering + decorating	£2,500	£5,000
Architect + planning + building control	£3,000	£6,000

Cost by UK region

Region	Typical cost
London	£84,375
South East	£78,125
South West	£68,750
Midlands	£62,500
North England	£56,250
Scotland	£59,375
Wales	£56,250

How to save money

• Build under permitted development if possible — saves time and £200–£400 in fees
• Bi-folds add 40 % more daylight than French doors for ~30 % more cost
• Move the kitchen only if you have to — every plumbing/electrical move adds £600+

How to find a trusted tradesperson

Get at least 3 quotes from vetted UK trade networks:

• Checkatrade
• MyBuilder
• Bark

FAQs

How much per m² for a single-storey extension?

Basic £2,000–£2,800/m²; mid-range £2,400–£3,500/m²; premium £3,500–£5,000/m². London adds 25–35 %.

Do I need planning permission?

Not usually for under 4 m (detached) or 3 m (terrace/semi). Up to 6/8 m is permitted under the Larger Home Extension scheme with prior approval.

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Disclaimer: Prices are guide ranges based on 2026 UK market data. Get quotes from local tradespeople for accurate pricing.