Knock-Through 2 Rooms Cost UK 2026

Knocking through two rooms (e.g. lounge-diner) to create one open-plan space is one of the most popular UK renovations. In 2026, expect £3,500–£9,000 including RSJ, engineer, and make-good.

Quick answer

Typical UK price range: £3,500–£12,000. Typical time: 4–10 days.

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Job type Remove load-bearing wall Remove partition wall Knock through (2 rooms) Open plan kitchen-diner Single RSJ only

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

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

Extras

Structural engineer fee £350–£800 Building control £250–£600 Make-good plastering £600–£1,500 Flooring make-good £400–£1,200 Localised rewire £350–£900

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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

• £3,500–£9,000 for a typical lounge-diner knock-through
• Almost always load-bearing — needs RSJ
• Doubles the perceived size of the ground floor
• Adds 3–8 % to property value

Cost breakdown

Item	Low	High
Engineer + building control	£600	£1,400
Wall removal	£1,000	£2,500
RSJ supply + install	£900	£2,800
Make-good (plaster + floor + electrics)	£1,000	£3,500

Cost by UK region

Region	Typical cost
London	£10,462
South East	£9,687
South West	£8,525
Midlands	£7,750
North England	£6,975
Scotland	£7,362
Wales	£6,975

How to save money

• Plan for new flooring across the whole space — boundaries between rooms always show
• Box the steel in flush with both ceilings — looks intentional
• Reposition radiators to match the new layout

How to find a trusted tradesperson

Get at least 3 quotes from vetted UK trade networks:

• Checkatrade
• MyBuilder
• Bark

FAQs

Will a knock-through add value?

Usually yes — 3–8 % uplift in older terraces and semis, especially in London. Estate agents value the open-plan feel.

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