A kitchen extension in London can vary significantly depending on whether you are creating a simple rear addition or a more design-led space with structural openings, rooflights, bespoke joinery, stone worktops and large-format glazing. The construction cost is only one part of the picture, because kitchens often involve more services, more specification decisions and a higher level of finish than other parts of the house. For many homeowners, the best approach is to think about the kitchen extension as both a building project and a major lifestyle upgrade.

In London, £40k may be enough for a smaller and relatively simple extension, but it is unlikely to cover a high-specification house extension in West London once structural works, glazing, finishes and professional input are taken into account. For period homes and more premium properties, budgets can rise quickly because of access constraints, party wall issues, drainage, kitchen fit-out and the cost of integrating the new space properly with the existing house. The more useful question is not whether a round number sounds enough, but what level of project that budget would realistically deliver.

In most cases, £20k is not a realistic budget for a full house extension in London. Even a relatively modest extension involves groundwork, structure, roofing, insulation, glazing, electrics, plastering and finishes, and costs increase further where site access is restricted or the house requires more careful detailing. For homeowners in West London, the bigger risk with an unrealistically low budget is not simply disappointment, but starting with the wrong expectations and ending up with compromises on quality, scope or programme.

The 50% rule generally refers to permitted development guidance stating that extensions and other additions must not cover more than half the land around the original house. It is one of several planning-related limits, and it does not mean a project is automatically permitted just because it falls within that threshold. In London, especially on period properties or homes in more sensitive settings, there may also be restrictions relating to height, depth, location, design and neighbouring impact. It is useful as an early rule of thumb, but it should never be treated as the only planning test.

The value added by a house extension depends on your location, property type, and the quality of the build. In many West London areas, a well-executed extension can increase the overall property value by 10–20%, sometimes more for high-demand neighbourhoods. For example, if a home is valued at £1 million, an extension could add £100,000–£200,000 to its market value.

Ultimately, the uplift comes not just from the extra square footage but also from the quality of design and finishes—features like open-plan kitchens, vaulted ceilings, or bespoke joinery often make the space more desirable and maximise return on investment.

Planning permission is not always required, because some projects can fall within permitted development rights. That said, many extensions in West London do need more careful review, particularly where the home is in a conservation area, forms part of a terrace, has been altered previously or involves a more visible or ambitious design. The safest approach is to assess the property, drawings and planning context early so the route to build is clear before procurement and pricing move too far forward.

Most house extensions in London take between a few months and several months to complete, depending on the size, type and complexity of the build. A straightforward rear extension will usually move faster than a more involved wraparound, double-storey or kitchen-focused project with structural alterations and bespoke finishes. The full timeline is also shaped by approvals, party wall matters, lead times for materials, weather, access constraints and how much reconfiguration is happening inside the existing house. A realistic programme should reflect the actual project rather than a generic promise.

The best type of extension depends on the existing layout, the width of the plot, the way the house is used and what you are trying to improve. For many Victorian and Edwardian homes in West London, rear and side-return extensions work especially well because they can create a larger kitchen, improve circulation and bring in more natural light. In other properties, a wraparound or double-storey extension may offer better long-term value. The right solution is not always the largest one, but the one that improves the way the house actually works.

Yes. Many house extension projects involve architects, interior designers, structural engineers and other consultants, and good coordination between those parties makes a major difference to the final result. Our role is to build the project properly on site, while helping ensure the drawings can be delivered in a practical, well-sequenced and high-quality way. For higher-value homes, this kind of coordination is especially important because the build needs to protect both the design intent and the standard of finish.

Yes. We manage the construction process from site setup through to completion, including procurement, sequencing, day-to-day coordination and final delivery. That helps keep the project more organised and gives the client a clearer point of contact throughout the build. On house extensions in London, where timing, access, neighbours and logistics can all affect progress, full construction management helps reduce disruption and keeps the work moving in a more controlled way.