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.

Architects in Clapham

Clapham splits across two councils. Most of it falls within Lambeth, while the streets nearest Wandsworth Common answer to Wandsworth instead. Design United Studio checks which one applies before a single drawing gets started, so a scheme is designed against the right set of rules from day one.

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Two Councils, One Straightforward Answer

Which Council Actually Covers Your Clapham Address

Lambeth and Wandsworth don't apply identical planning policy, conservation area boundaries or Article 4 directions, so a scheme that's straightforward on one side of Clapham can face different requirements a few streets over. Director Jürgen Kuppers has taken projects through both councils, so the right authority gets identified early rather than assumed.

Clapham's Conversions Bring Their Own Set of Rules

A large share of Clapham's housing stock is flats carved out of larger Victorian houses, and permitted development rights that apply to a house don't automatically extend to a flat.

Almost every alteration to a flat, including a loft conversion, typically needs full planning permission. Freeholder consent is often needed on top of that, which is worth resolving early rather than after a scheme has already been designed around an assumption that turns out to be wrong.

Making More of a Family House Near the Common

Clapham Common draws a lot of growing families to the surrounding streets, and a side return or rear extension is usually how they make an existing Victorian terrace work for a bigger household.

Kirana Laonipon, our Part II architectural assistant, coordinates the drawings and specification through to building control, so nothing gets lost between design and site.

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Clapham Old Town and the Streets Around the Common Are Conservation Areas

Much of Clapham Old Town, along with several streets closest to the Common, sits within a conservation area. That limits what can change without planning permission and shapes the materials and detailing a scheme can realistically use.

Modern Family Living Inside a Period Shell

Most Clapham enquiries want the front of a Victorian house left largely alone and the inside reworked entirely, an open-plan kitchen-diner, better light, more storage.

We treat the interior design and the structural extension as one brief, so the finished space works as a whole rather than as a new room bolted onto an old layout.

Straight Talk, No Hand-Offs

The Same Two People From Clapham to Completion

Design United Studio is led by director Jürgen Kuppers, a RIBA and ARB registered architect with a background in large-scale projects at Foster + Partners, working alongside Part II Architectural Assistant Kirana Laonipon.

Clapham is one of eighteen areas we cover as part of our wider South West London architects practice, with the same two people on a project from first sketch through to completion.

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