Architects for Extensions & Planning Applications  in Spelthorne

Planning permission, architectural design and project management  delivered end-to-end by a multi-award-winning local team.

All In One Architectural Solution In Spelthorne

Planning applications handled for Spelthorne — council decisions arrive in 8 weeks standard.
Green Belt and protected land affect extensions — full planning is often required.
Full design, planning, and building regulations delivered together under one fixed fee.
Loft conversions available — Velux, dormer, and hip-to-gable options all designed in-house.
In-house structural engineer included — no separate specialist needed for your calculations.
A 98% planning approval rate achieved across 30+ completed Spelthorne projects locally.

Extension Architecture handles planning applications, house extensions, and loft conversions across Spelthorne and the wider Spelthorne area, including TW15, TW18, TW19. Many streets keep Permitted Development rights, but Green Belt land often needs planning. Our in-house structural engineer and RIBA-chartered team manage every stage, from survey to completion. Council decisions take 8 weeks. Get your free quote today.

We only deliver excellence

80⁺

Projects completed in Spelthorne

2220 ⁺

Our total projects completed in London & Surrey

Locations in Spelthorne

Staines-upon-Thames • Ashford • Sunbury-on-Thames • Shepperton • Stanwell • Laleham

Postcodes Served

TW15, TW18, TW19

Our Expertise

Planning Application Drawings
Council-ready drawings, fast

3D Visualisations
See it before building

Retrospective Planning
Fix unpermitted works

Building Regulation Drawings
Safe, compliant drawings

Commercial Development Consultancy
Change of use experts

Interior Design
Finishes inside out

Spatial Planning & Layout
Smarter room layouts

Feasibility Consultancy
Know what’s possible

Recent Spelthorne Architects Extension & Loft Conversion Projects

What makes Spelthorne Special?

A beautiful fusion of historical charm with modern amenities, Spelthorne is an ideal place to see the wonderful natural beauty and urban accessibility. It is made up of picturesque riverside areas such as Shepperton and Sunbury lying between the River Thames and Greater London. Laleham and lower Halliford are preserved in the borough’s conservation areas and their historical architecture and heritage give these neighbourhoods distinctive character. While such development within these protected areas is constrained, our knowledge means that every development in Spelthorne meets these valued enclosures’ distinctive architectural identity and benefits them.

Moreover, Spelthorne’s massive Green Belt areas are essential to defending against the burden of overdevelopment, while at the same time providing open spaces in a harmonious juxtaposition of greenery to the characteristics of each neighbourhood. With such spaces being such a key part of Spelthorne’s appeal they serve to bring residents and visitors alike the refreshing natural environment. But our team is dedicated to making these projects complement that balance, delivering innovative solutions that reflect Spelthorne’s history, character and landscapes.

1930s semis and detached homes dominate TW15 — ideal for rear and loft projects.
Green Belt and protected land restrict development — full planning is usually required.
Strong local demand means well-designed extensions consistently add lasting property value.
Spelthorne Council works to a clear 8-week householder planning decision timeline.

Interior fit-out, Spelthorne

What Our Clients Say About
Extension Architecture

Interior fit-out, Spelthorne

Spelthorne Planning Applications and Architectural Services

At Extension Architecture we are dedicated Spelthorne architects not just for creating design, but surroundings that help create your lifestyle and complement the borough’s surroundings perfectly. Whether it’s a small extension or a full sized residential build, we consistently perform outstanding work that exceeds expectations and is in keeping with Spelthorne’s unique architectural design. We understand the borough’s planning regulations to a depth, and we appreciate the city’s heritage for what it is, and how we can make designs that celebrate and enliven what pays homage to it.

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Explore before & after visuals of our extension builder projects

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Before

After

Why Choose Extension Architecture?

Our experienced team of Spelthorne architects will take the lead and create a thoughtful design that maximizes the available space and is tailored to your tastes. We will guide you through the intricacies of the planning process and discuss every aspect of the project in detail. Our architects will carefully survey your property to ensure no detail is overlooked. We will be with you throughout the process, providing clearand comprehensive instructions while walking you through the planning, application and construction process.

One-Stop Solution

Our firm provides a comprehensive range of services under one roof, from planning and architectural design to intricate interior and immersive design, and expertly manages the complexities of the construction process. We have delivered projects of various scales and budgets, from small home extensions to large new builds, for a diverse clientele.

In-house Structural Engineer

Our in-house structural engineer—an advantage that only 1 in 20 firms can offer. This is crucial, as significant time is often lost consulting multiple specialists, which can lead to additional costs. With a structural engineer on our team, we ensure a fully collaborative and seamless design-build process, minimizing contingencies and preventing design inaccuracies.

Interior Design + Architecture

Our team includes interior designers who work closely with the clients, especially the ‘ladies’ of the house to curate the dream spaces tailored to their requirements. These processes include fun yet crucial processes like selecting wall finishes, color schemes, soft furnishings, flooring. Having architects and interior designers under one roof allows for less contingencies.

Turn-Key Approach

We provide support throughout the entire building process, embracing a ‘turnkey approach’ to ensure a smooth and efficient project from start to finish. Additionally, we assist in reducing build costs by aiding in the procurement of all internal fit-outs, including sanitaryware, kitchens, and more. It’s a zero hassle solution for clients.

Start Planning an Extension Home today

If you are planning a house extension in London, our architects can guide you through the entire process from concept design to construction.

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Architectural design consultation and home extension planning services

Years of Experience

17

Any Questions?

Didn’t find your answer? Feel free to reach out

It depends on location. Green Belt and protected land across Spelthorne usually require a full application to Spelthorne Borough Council, even for small extensions. Streets outside those designations often keep Permitted Development rights. We check your address free of charge before any design begins.

Spelthorne properties suit single-storey rear extensions, double-storey additions, side returns, loft conversions, and wraparound extensions. The dominant stock across TW15, TW18 is 1930s semis and detached homes, which responds well to these approaches. We advise on the right option for your home and budget free of charge.

Yes, but there’s a ceiling on how much you can add — the council generally wants any extension to be a “proportionate” increase over the size of the original house, and they look at each case individually. Conservation areas like Laleham face a similar squeeze, just for a different reason (protecting the look of the area rather than the open land). We’ll walk your plot and tell you honestly what’s realistic before you spend a penny on design.

Spelthorne Borough Council targets 8 weeks for householder applications from validation. Conservation area or more complex cases can take up to 13 weeks. Once granted, permission stays valid for 3 years. We track every application closely and respond to any council queries immediately on your behalf.

Fair question. We’ve done 80+ projects in Spelthorne alone, part of over 2,220 across London and Surrey, and we’ve been doing this for 17 years. We’re RIBA-chartered and ARB-registered, we keep a structural engineer in-house (most firms don’t — it’s roughly 1 in 20), and our planning approval rate sits at 98%. None of that costs you anything to find out — the first feasibility check is free.

It happens, but it’s rarely the end of the road — a lot of refused applications get revised and resubmitted, or go to appeal, depending on why the council said no. We try to avoid getting there in the first place by checking your site against the planning constraints before we design anything, which is a big part of why our approval rate sits at 98%.

Architects for Extensions & Planning Applications  in Spelthorne