Three open-plan typologies
Type 1 — knock-through only: combine existing dining + kitchen by removing the dividing wall. Cheapest, fastest, no planning needed. £8k–£18k incl. RSJ if loadbearing. Type 2 — knock-through + new kitchen: as above plus full new kitchen, appliances and flooring. £25k–£42k mid-range, £55k–£95k high-end. Type 3 — extension creates new open-plan: side return, rear extension or wraparound to create the open-plan space. £58k–£140k. Most London open-plans are Type 2 or Type 3.
Kitchen specification tiers
Standard volume-brand kitchen (Howdens, Wickes, Magnet): £6k–£14k supply, £3k–£5k install. Mid-range branded (Wren, Wickes Premier, John Lewis of Hungerford): £14k–£28k supply, £4k–£7k install. High-end German handleless (LEICHT, Schüller, Häcker): £28k–£70k supply, £6k–£10k install. Bespoke painted (Plain English, Devol, Naked Kitchens): £45k–£120k+ supply, £8k–£14k install. Appliance budget typically £4k–£18k separately. Worktops: laminate £400–£900, quartz £2k–£4k, natural stone £3k–£8k.
Ventilation, services and lighting
Open-plan kitchens need careful extraction — combustion ventilation if gas hob retained (5 m³/min minimum), or full external venting for induction. Most projects switch to induction for simpler ventilation. Lighting: layered scheme (downlights for task, pendants for island, wall washers for dining) — £1,800–£4,500 design + supply + install. Underfloor heating typical add £80–£140 per m² for water-fed or £60–£90 per m² electric. M&E rewire to support new layout: £3k–£8k.
