Do I need an architect for a house extension?

Not legally, but for anything beyond a small permitted development extension, an architect's drawings are usually needed for planning and building regulations. An architect also helps avoid costly design mistakes before building work starts.

How long does a house extension take from design to completion?

Design and planning typically take a few months. Build time depends on size and complexity, a single storey side return is far quicker than a two storey rebuild.

Can I extend without planning permission?

Many single storey rear and side return extensions qualify under permitted development. Larger extensions, wrap-arounds, and properties in conservation areas or listed buildings usually need a full application.

Do I need a party wall agreement for a house extension?

If your extension involves work on or near a shared wall or boundary with a neighbour, you'll usually need a party wall agreement under the Party Wall Act. We flag this early so it doesn't hold up the build once work is ready to start.

Does a house extension add value to my home?

A well-designed extension usually increases a property's value, though the actual return depends on the local market, the quality of the finish, and how well the new space suits the house.

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New Build Architects London

As new build architects working across London, we design bespoke homes from the ground up, from first sketch through to planning permission and construction.

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The Case For Architect-Led New Builds

Why a New Build Needs an Architect From Day One

A new build lives or dies on decisions made before a spade goes in the ground, orientation, how the house relates to neighbouring properties, where the light falls through the day.

Bringing an architect in at the outset means those decisions get made properly the first time, rather than worked around later.

Bespoke Home Design Built Around How You Actually Live

As bespoke home architects, we start with how a household actually uses space, not a template floor plan. That means asking practical questions early: where the morning light lands, how a family moves through the ground floor, whether a home office needs to be properly separate from the rest of the house.

Getting a New Build Through Planning Permission

New build applications get more scrutiny than extensions, particularly on infill plots or in conservation areas.

We prepare the drawings, design and access statements, and supporting documents the local planning authority expects, and handle direct liaison with planning officers where useful.

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Site Assessment and Feasibility, Before You Commit

Not every plot supports the house a client has in mind, and it's far cheaper to find that out early. A feasibility study looks at the site's constraints, access, boundaries, existing trees, drainage, overlooking, before any real design work starts, so the brief is grounded in what the site can actually deliver.

Designing a New Build That Performs Well Long-Term

A new build is a genuine opportunity to get insulation, glazing, and heating strategy right from the outset, rather than retrofitting them into an existing structure later. We design to current Building Regulations standards and advise on where it's worth exceeding them.

Why Design United Studio

A RIBA and ARB Registered Practice, Based in South West London

Design United Studio is led by RIBA and ARB registered architects with over ten years in practice, based in Wimbledon and working across South West London and Surrey. We handle new build projects end to end, from feasibility through to the final fit-out.

Portfolio

Our Track Record

2

Hands-On Team

100+

Projects

99%

Planning Approval Success Rate

10+

Years in Practice

Hear From People We've Worked With

"We came to Design United Studio with a difficult, narrow plot and no clear idea if a house would even fit. They found a design that not only worked, but genuinely made the most of the site."

"As bespoke home architects go, they listened more than most. The final layout reflects exactly how our family actually lives, not a generic new build floor plan."

"Planning permission was our biggest worry going in. The team handled the whole application and kept us updated at every stage."

HELEN R.

DAVID M.

FIONA A.

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