House Extension Architects

While home extensions form the core of this page, they are delivered with the same architectural discipline and technical rigour that underpin all of our residential work.

As RIBA Chartered architects, we approach each extension with careful attention to proportion, natural light and material continuity — ensuring that new spaces feel considered and seamlessly integrated with the existing home.

Whether extending or reconfiguring a property, our role is to strengthen how the house functions as a whole. Working across London and the Home Counties, we apply a measured, planning-led approach that balances design ambition with buildability and long-term performance.

Rear and side return extensions are among the most effective ways to unlock space in a London home. Whether you are widening a narrow Victorian terrace or extending into the garden, the success of the project lies in careful proportion, light and integration with the existing structure.

A side return extension can transform an underused passage into a generous kitchen and dining space, improving flow and bringing natural light deeper into the plan. A rear extension allows you to reshape the relationship between house and garden, often creating a more open, connected ground floor suited to modern living.

We approach each project with a clear understanding of structural constraints, neighbouring properties and local planning policies. Rather than treating the extension as an add-on, we design it as a natural continuation of the home — ensuring materials, detailing and spatial rhythm feel coherent and well resolved.

From early feasibility and planning discussions through to technical drawings and construction coordination, we guide you through the process with clarity and care. The result is an extension that feels balanced, considered and built to last.

The cost of a house extension will depend on several factors, including its size, structural complexity and the level of finish you’re aiming to achieve. As a broad indication, a carefully designed extension project typically starts in the region of £2,000–£3,000 per square metre. For more complicated or high-end schemes — involving bespoke detailing, larger areas of glazing, premium materials or specialist construction — costs often range between £3,000–£4,000+ per square metre.

Beyond square metre rates, planning requirements, structural modifications, ground conditions, glazing specifications, bespoke joinery, interior finishes and energy performance standards all influence the investment.

Engaging an experienced residential architect early in the process helps bring clarity to these variables and align design decisions with your budget.

Full Guide on House Extension Cost

Extending a home in London often involves navigating borough-specific planning policies, permitted development rules and local design guidance. Whether your property falls within a conservation area, is subject to Article 4 restrictions, or requires a full planning application, early clarity is essential.

We integrate planning strategy into the design process from the outset. Before developing detailed proposals, we assess site constraints, neighbouring properties, overlooking considerations, scale, massing and materiality.

For many rear and side return extensions, permitted development rights may apply. However, previous alterations, property type or local restrictions can affect eligibility. Where formal permission is required, we prepare and submit the necessary drawings and supporting documentation, managing correspondence with the local authority.

By aligning design ambition with planning policy, we aim to minimise delays and reduce risk.

An experienced extension architect is responsible not only for the visual design of a new addition, but for ensuring it integrates structurally, technically and spatially with the existing building. In London homes — particularly Victorian and Edwardian terraces — this often involves complex structural alterations, load-bearing wall removals and steelwork to create open-plan layouts.

We assess site constraints, neighbouring properties and existing foundations at an early stage, working closely with structural engineers where required. Careful consideration is given to ceiling heights, floor levels and junction details so that new and existing spaces align seamlessly.

Glazing strategy is equally important — balancing daylight, privacy and thermal performance to meet current building regulations without compromising architectural clarity.

From feasibility studies and planning applications through to detailed construction drawings and on-site coordination, our role is to guide the project through each stage with precision.