House Extension Design Ideas: Open Plan Kitchen Diner London 2026

The open plan kitchen diner extension is the single most popular home improvement in London. By extending the rear or side of the property and opening up the ground floor, homeowners transform a cramped, separated kitchen into a large, light-filled space for cooking, dining and living. In 2026, a well-designed open plan kitchen diner extension can completely change the way a family uses their home and significantly increase the property's value.

A completed open plan kitchen diner extension by LCCL Construction in London

If you are looking for house extension design ideas for an open plan kitchen diner in London, this guide covers the best layouts, features and finishes to inspire your project. LCCL Construction has designed and built hundreds of open plan kitchen diner extensions across London and Hertfordshire.

House Extension Design Ideas for an Open Plan Kitchen Diner in London

Rear extension with full-width bifold doors: The most popular layout in London. Extending the rear of the property by 3 to 6 metres and fitting full-width bifold or sliding doors across the entire rear elevation creates a seamless connection between the kitchen diner and the garden. When the doors are fully open in summer, the inside and outside become one space.

Side return extension with roof lantern: Filling in the narrow side alley adds width to the kitchen rather than depth. Combining a side return with a large roof lantern brings natural light flooding into the centre of the new space. This layout works particularly well for Victorian and Edwardian terraced houses in North London.

Wraparound extension with island kitchen: Combining a rear extension and side return in an L-shape creates the largest possible open plan ground floor space. This layout accommodates a full island kitchen, a large dining table and a separate sitting area in a single open plan room. See our guide to wraparound extensions in London for more detail.

Key Design Features for an Open Plan Kitchen Diner Extension

Roof lanterns and skylights: Bringing natural light into the centre of the new space is one of the most important design decisions. A large roof lantern or series of skylights transforms what could feel like a dark addition into a bright, airy room. LCCL Construction regularly installs roof lanterns up to 3 by 2 metres as part of extension projects.

Bifold and sliding doors: Full-width rear glazing is the signature feature of a London kitchen extension. Bifold doors fold back to create a completely open rear elevation. Sliding doors offer a slimmer frame and a more contemporary look. Both create a strong visual connection to the garden and allow the space to be opened fully in warm weather.

Kitchen island: An island is a central feature of most open plan kitchen diners. It provides additional worktop and storage space, creates a natural division between the cooking and dining areas, and gives the room a focal point. LCCL Construction works with your kitchen supplier to ensure the structural layout accommodates the island position.

Underfloor heating: Underfloor heating is a popular choice for kitchen extension floors, particularly with stone or porcelain tiles. It eliminates radiators from the walls and allows the full floor area to be used without restriction. LCCL Construction installs electric or water-fed underfloor heating as part of the first fix.

Structural steel and open sightlines: Opening up the ground floor between the original house and the new extension requires structural steel beams. LCCL Construction's structural engineers design the steelwork to minimise column positions and create the widest possible open sightlines between spaces.

Open Plan Kitchen Diner Extension Flooring Ideas

Large format porcelain tiles: The most popular choice for open plan kitchen extensions in London. Large format tiles — typically 600mm by 600mm or larger — minimise grout lines and create a clean, contemporary look. They are easy to maintain and work well with underfloor heating.

Engineered oak flooring: A warmer, more traditional option that complements period properties. Engineered oak can be laid on a floating floor over underfloor heating and creates a seamless transition from the original house into the extension.

Polished concrete: A high-end, industrial option increasingly popular in contemporary London extensions. Polished concrete floors are poured on site, thermally efficient and extremely durable.

How Much Does an Open Plan Kitchen Diner Extension Cost in London?

The cost of an open plan kitchen diner extension in London depends on the type of extension, size and specification. As a general guide, a rear extension starts from around £35,000, a side return from £42,000 inc. VAT (£35,000 + VAT) and a wraparound from £72,000 inc. VAT (£60,000 + VAT). These estimates cover the structural build only — kitchen furniture, appliances and flooring are separate costs. See our complete guide to house extension costs in London for a full breakdown.

Why Choose LCCL Construction for Your Kitchen Extension?

LCCL Construction is an award-winning design and build company based in Finchley, North London with over 20 years of experience designing and building open plan kitchen diner extensions across London and Hertfordshire. Our LABC Award 2024 for Best Residential Project reflects the quality of every project we deliver. We have over 200 verified reviews at 4.7 out of 5.

We handle everything from architectural design and planning through to structural engineering, building regulations and construction — one company, one point of contact. To start planning your open plan kitchen diner extension, call us on 020 8037 7332 or get an instant quote online.