Why Eltham is perfect for kitchen extensions
Eltham and Mottingham sit in the heart of South-East London across the SE9 and SE12 postcodes, and the local housing stock is almost purpose-built for kitchen extension projects. The area is dominated by 1930s semi-detached and detached houses with generous rear gardens, solid brick construction and relatively simple roof structures. These properties were built with separate kitchens, dining rooms and living rooms - a layout that made sense ninety years ago but feels cramped and disconnected by modern standards. A kitchen extension opens up the ground floor, connects the cooking space to the dining and living areas, and creates the kind of open-plan family hub that transforms daily life.
The SE9 and SE12 postcodes fall under the Royal Borough of Greenwich for planning purposes. Greenwich Council has well-established policies on residential extensions, and the majority of single-storey rear kitchen extensions in Eltham qualify for permitted development. The combination of supportive planning context, suitable housing stock, generous plot sizes and strong property values makes Eltham one of the best areas in South-East London for kitchen extension projects.
RCB Design and Build has completed kitchen extensions across Eltham, Mottingham, New Eltham and the surrounding areas. We understand the structural characteristics of 1930s construction in this area, the ground conditions (London clay is prevalent), and the specific design opportunities that these properties offer. Our free project review is the starting point for every kitchen extension enquiry.
Kitchen extension costs in Eltham: 2026 figures
Kitchen extension costs in Eltham and Mottingham in 2026 start from GBP 50,000 for a standard single-storey rear extension of approximately 20 square metres with bi-fold doors, structural steelwork, full electrical and plumbing installation, underfloor heating preparation, plastering, decoration and flooring. This price includes everything needed to create a finished, habitable space ready for the kitchen fitter.
A larger extension of 25-35 square metres with a roof lantern, more complex structural alterations and higher-specification finishes typically costs GBP 65,000-GBP 90,000. A double-storey rear extension adding a kitchen-diner on the ground floor and a bedroom or bathroom above ranges from GBP 85,000 to GBP 120,000. These figures reflect the South-East London market and include a level of finish consistent with the area.
Kitchen units, appliances, worktops and splashback tiling are client-supplied items that sit outside the build contract. This is standard practice and gives you complete freedom to choose your kitchen supplier, style and budget. We prepare the space with all connections, points and surfaces ready for a seamless kitchen installation. Many of our Eltham clients spend between GBP 8,000 and GBP 25,000 on their kitchen fit-out depending on the supplier and specification chosen.
Planning and Building Regulations in Greenwich
Most single-storey kitchen extensions in Eltham fall within permitted development rights and do not require a formal planning application to Greenwich Council. The standard permitted development limits allow a rear extension of up to 3 metres on a semi-detached house or 4 metres on a detached house, with a maximum height of 4 metres. The larger home extension scheme permits up to 6 metres on a semi-detached or 8 metres on a detached house, subject to a prior approval notification to Greenwich Council and a 42-day neighbour consultation period.
Even where planning permission is not required, Building Regulations approval is always necessary for a kitchen extension. This covers structural design, foundations, drainage, insulation, ventilation, electrical installation and fire safety. Greenwich Council's Building Control service or an approved inspector must inspect the work at key stages and issue a completion certificate at the end. RCB Design and Build manages the entire Building Regulations process and ensures the completion certificate is issued before final handover.
Properties in certain parts of Eltham may have specific restrictions. The Eltham Palace and surrounding area has conservation area status, and some properties along the main road corridors may have Article 4 directions. We check the planning status of every property at the project review stage and advise on the correct route before any design work begins.
Designing the perfect open-plan kitchen extension
The design of an Eltham kitchen extension typically revolves around three key elements: the connection to the garden through glazing, the kitchen layout including island or peninsula positioning, and the integration of the existing ground-floor rooms into the new open-plan space. Getting these three elements right determines whether the extension feels like a natural evolution of the house or an awkward addition.
Bi-fold doors are the most popular glazing choice for Eltham kitchen extensions, typically spanning 3-4 metres of the rear wall and folding back to create a wide opening onto the garden. Sliding doors are an alternative that some clients prefer because they do not swing into the room when open and have slimmer sightlines. Aluminium frames in anthracite grey are the dominant choice in the SE9 and SE12 market, offering clean contemporary lines that complement both the 1930s exterior and a modern interior.
Kitchen islands have become a central feature of almost every open-plan kitchen extension we build in Eltham. An island of 2.4 metres by 1.2 metres provides preparation space, storage, a breakfast bar for casual seating and a visual anchor that defines the kitchen zone within the larger open-plan room. We position electrical sockets, water supply and waste connections in the floor slab during the groundworks phase so that island services are concealed beneath the finished floor. Underfloor heating is strongly recommended for kitchen extensions on concrete slabs - it eliminates radiators from the walls, distributes heat evenly across the floor and works efficiently with the insulated slab construction.
Structural considerations for 1930s semis in Eltham
Extending a 1930s semi in Eltham involves removing a significant portion of the rear wall - typically the entire width of the kitchen and dining room - and supporting the structure above with steel beams. The size of the steelwork depends on the span and the load from above: a single-storey extension under a first-floor bedroom requires larger steels than one under a non-structural area. We commission structural engineer's calculations for every project and the steel design is specific to your property.
Foundation design is particularly important in Eltham due to the prevalence of London clay, which is classified as a high-shrinkage soil. Foundations on London clay must be deeper than on other soil types to account for seasonal ground movement caused by moisture changes. Standard strip foundations in Eltham are typically 1.0-1.5 metres deep, though this can increase to 2.0 metres or more where mature trees are nearby. The additional depth adds cost but is non-negotiable for structural integrity and Building Regulations compliance.
Drainage is another important consideration. The existing drainage run from the kitchen typically exits through the rear wall and connects to the sewer in the rear garden. When the extension is built over this drainage run, it must be re-routed or protected with a lintel. We survey the existing drainage as part of our site assessment and include any necessary modifications in the quoted price.
Getting started with your Eltham kitchen extension
RCB Design and Build offers a free project review for every kitchen extension enquiry in Eltham, Mottingham, New Eltham and the surrounding SE9 and SE12 postcodes. We visit your property, discuss your vision for the space, assess the structural and planning context, and provide honest guidance on costs and programme. There is no obligation and no pressure - we want you to have the information you need to make a confident decision.
We are registered with the Federation of Master Builders, accredited by TrustMark and verified on Checkatrade. Our deposit is 5% of the contract value and payments are staged against completed milestones throughout the build. Every kitchen extension is completed to full Building Regulations standard, signed off with a completion certificate and covered by our workmanship guarantee. A typical single-storey kitchen extension in Eltham takes 10-14 weeks from groundworks to handover.
To discuss your kitchen extension project, call us on 07359 872594 or request a free project review through our website. We will arrange a convenient time to visit and get the conversation started.
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