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.
TL;DR - The Quick Answer
An open plan kitchen extension combines cooking, dining, and living into a single connected space, typically requiring 30-50m² for comfortable use. Removing load-bearing walls requires steel beams costing £1,500-£8,000 depending on span. Total project budgets typically run £75,000-£120,000 including structural work, kitchen fit-out, and glazing. Ducted extraction, zoning with lighting and floor finishes, and careful layout planning are essential to making open plan living practical day-to-day.
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.
| Layout | Minimum size | Typical all-in cost | Best for |
|---|---|---|---|
| Kitchen island | 35–50m² | £90,000–£120,000 | Larger extensions, sociable cooking |
| Galley with dining end | 25–35m² | £75,000–£100,000 | Narrower side returns, smaller budgets |
| L-shaped kitchen | 30–45m² | £80,000–£110,000 | Varied room shapes, peninsula option |
| Broken plan | 30–50m² | £85,000–£120,000 | Flexibility to close off cooking zone |
Source: Mayfair Studio project data • Data as of 2025
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.
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
Structural Considerations
Creating open plan usually means removing walls. Load-bearing walls need steel beams (RSJs).
| Opening | Typical 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 |
An open plan kitchen extension in London typically costs £75,000–£120,000 all-in, including structural steelwork, kitchen fit-out, and glazing. You need at least 30m² for a comfortable kitchen and dining area, and 35–50m² to include a living zone. Removing load-bearing walls costs £1,500–£8,000 depending on span. Budget 15–20% of project cost for glazing.
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.