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.

Listed Building Architects London

As listed building architects, we help owners extend, alter, and restore heritage properties across London without compromising what makes them special, or falling foul of the consent process along the way.

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Specialist Knowledge

Why Listed Buildings Need a Different Kind of Architect

A listed building comes with legal protections that ordinary planning rules don't touch, and a design that would sail through on a standard property can be refused outright here. As heritage architects, we understand which changes conservation officers are likely to support, and which ones will draw immediate objection.

Getting Listed Building Consent

Listed building consent is a separate process from planning permission, and both are often needed together.

We prepare the heritage statements, drawings, and supporting evidence a local authority conservation team expects, and manage direct liaison with the case officer throughout.

Designing Extensions That Respect the Original Building

The strongest listed building applications don't try to disguise new work as old, they make clear what's original and what's new, while keeping the two in genuine dialogue. We design extensions and alterations that read as considered additions rather than pastiche.

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Building a Working Relationship With the Local Conservation Team

Conservation officers aren't an obstacle to design around, they're a resource. Early, informal conversations with the local conservation team often shape a stronger proposal than working in isolation and hoping for the best at submission.

Choosing Materials That Match the Building's Fabric

Getting a listed building application approved often comes down to detail, brick bond, window proportions, pointing technique, roofing material. We specify materials and junctions that genuinely match the existing fabric, not approximate it.

Why Design United Studio

A RIBA and ARB Registered Practice With Heritage Experience

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've guided listed building projects through consent from first survey to completed build.

Portfolio

Our Track Record

2

Hands-On Team

100+

Projects

99%

Planning Approval Success Rate

10+

Years in Practice

What Our Clients Say

"We'd been told our listed building would never get consent for an extension. Design United Studio proved that wrong, and the result respects the house completely."

"As heritage architects, they understood the building in a way our previous architect never did. The conservation officer's feedback was positive from the first meeting."

"The whole listed building consent process felt daunting until we started working with this team. They handled every piece of paperwork and kept us informed throughout."

MARGARET S.

ROBERT D.

CHARLOTTE W.

"The whole listed building consent process felt daunting until we started working with this team. They handled every piece of paperwork and kept us informed throughout." — Charlotte W.

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