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Kitchen Design11 min read • Updated Jan 2025

Open Plan Kitchen Extension: Design Guide

How to design the perfect open plan kitchen extension. Layout options, zoning strategies, and tips for making open plan living work.

Quick Answer

Open plan extensions need 30-50m² for comfortable kitchen/dining/living. Require structural steel when removing walls. Budget £75k-120k including fit-out.

30m²

Min Size

£75-120k

Typical Cost

£2-8k

Steel Beam

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Open plan kitchen extensions are the most popular home improvement in London. They transform how families live—cooking, eating, and relaxing in one bright, connected space. But they require careful planning to avoid common pitfalls like noise, smells, and impractical layouts.

Popular Layout Options

Kitchen Island Layout

Central island divides cooking from dining/living. Allows chef to face guests. Needs minimum 1m circulation around island. Most popular for larger extensions.

Galley With Dining End

Kitchen units along walls, dining table at the end near garden doors. Works well in narrower side returns. Good for smaller budgets.

L-Shaped Kitchen

Kitchen in corner, open dining and living area. Often combined with breakfast bar peninsula. Flexible for various room shapes.

Broken Plan

Open plan with partial dividers—sliding doors, half walls, or ceiling drops. Offers flexibility of open plan with ability to close off cooking.

Zoning Your Space

Without walls to define areas, use other techniques to create distinct zones:

Floor Changes

Different flooring materials—tile in kitchen, wood in living. Level changes (consider accessibility).

Ceiling Treatment

Dropped ceiling over kitchen with integrated lighting. Exposed ceiling in living area for height.

Lighting Zones

Different lighting circuits for each area. Pendants over dining, task lights in kitchen, ambient in living.

Furniture Placement

Sofa back defines living area. Rug anchors seating group. Island or table separates kitchen zone.

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Dealing With Cooking Smells

The biggest complaint about open plan kitchens. Good extraction is essential:

  • Extract rate: Minimum 12x room volume per hour for open plan
  • Ducted extraction: Always better than recirculating—removes odours entirely
  • Downdraft or ceiling extractors: For islands without overhead space
  • Make-up air: Large extractors need replacement air supply

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Structural Considerations

Creating open plan usually means removing walls. Load-bearing walls need steel beams (RSJs).

OpeningTypical Cost
Single opening (up to 3m)£1,500 - £3,000
Large opening (3-5m)£2,500 - £5,000
Full width beam£4,000 - £8,000

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Frequently Asked Questions

How big does an open plan kitchen need to be?

Minimum 25sqm for comfortable kitchen/dining. 35-50sqm for kitchen/dining/living with island. Under 25sqm can feel cramped when combining multiple functions.

Will open plan affect my heating bills?

Larger spaces take longer to heat but well-insulated new extensions are efficient. Underfloor heating works well—heats entire floor evenly. Zone controls help manage costs.

Can I keep a separate utility room?

Highly recommended. A small utility keeps washing machines, boilers, and cleaning supplies out of sight and reduces noise in your open plan space.

Last updated: January 2025

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Open Plan Kitchen Extension London 2025: Design, Costs & Layout Ideas | Mayfair Studio