Side Return Extension Cost UK 2026

A side-return extension fills in the awkward alley space beside the kitchen of a Victorian or Edwardian terrace — typically adding 6–10 m² and opening up the kitchen. In 2026, expect £35,000–£70,000 depending on glazing and spec.

Quick answer

Typical UK price range: £35,000–£80,000. 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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Estimate only. Prices reflect 2026 UK market data — get quotes from local tradespeople for accurate pricing.

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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

• Adds 6–10 m² of valuable kitchen-diner space
• £2,200–£3,000/m² — slightly more than rear extensions
• Usually permitted development on Victorian terraces
• Best paired with full kitchen refit (typical total £55,000–£90,000)

Cost breakdown

Item	Low	High
Foundations + groundworks	£4,500	£8,500
Side wall + roof	£10,000	£18,000
Roof lantern / glazing	£3,000	£7,000
Electrics + plumbing	£3,500	£6,500
Internal finish	£3,000	£6,000

Cost by UK region

Region	Typical cost
London	£77,625
South East	£71,875
South West	£63,250
Midlands	£57,500
North England	£51,750
Scotland	£54,625
Wales	£51,750

How to save money

• Always include a roof lantern — without one, the new room is dark
• Sometimes the existing rear wall stays — saves money
• Combine with rear extension for "wrap-around" if budget allows

How to find a trusted tradesperson

Get at least 3 quotes from vetted UK trade networks:

• Checkatrade
• MyBuilder
• Bark

FAQs

Do side returns need planning permission?

Most are permitted development on Victorian/Edwardian terraces as long as you stay within the side-return alley footprint and don’t exceed 4 m rear projection.

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