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 Surrey

Surrey isn't a stretch for us, it starts almost exactly where our South West London work already reaches, a few minutes past Kingston and Richmond. Design United Studio, led by director Jürgen Kuppers, works across the county with that same local footing.

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Already on Surrey's Doorstep

Why Surrey Isn't a Detour From Our Usual Work

Our studio sits in Wimbledon Park, close enough to the Surrey border that projects in Kingston and Richmond already put us most of the way there.

Surrey towns like Esher, Cobham, Weybridge, Epsom, Guildford and Woking aren't a separate service area so much as a natural continuation of the same practice. Jürgen designs across that whole stretch, from inner London terraces to the more spread-out properties Surrey tends to offer.

Surrey's Planning Isn't Run by a Single Council

Unlike a London borough, Surrey doesn't have one planning authority covering the whole county. It's split across several district and borough councils, including Elmbridge, Guildford, Epsom and Ewell, Mole Valley and Woking, each with its own local plan.

We confirm which authority actually applies to a property before design work starts, rather than assuming a single approach will fit wherever in Surrey a project happens to be.

Designing Within the Green Belt

A significant part of Surrey sits within the Metropolitan Green Belt, where new development faces a much higher bar than it would elsewhere.

Extensions to an existing house are generally treated differently to new development, but most local plans still cap how much a property can grow before it counts as disproportionate.

We check the specific limits that apply under the relevant council before finalising a design, so a scheme is shaped by what's actually achievable rather than reworked after a refusal.

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Bigger Plots Bring Bigger Design Decisions

A Surrey property often comes with considerably more land than an inner-London terrace, which opens up options that simply aren't on the table on a smaller plot: a detached garden studio, an orangery, or an extension that wraps around more than one side of the house.

More space means more decisions, not fewer, since a bigger plot can absorb a badly judged addition just as easily as a well-judged one.

Families Moving Out of London Still Want London-Level Design

A lot of our Surrey enquiries come from people who've relocated from London and don't want to compromise on the standard of design or project management they'd have expected to get there. Moving further out doesn't have to mean settling for less rigour on a project.

A London Studio, Genuinely Local to Surrey Too

The Same Two People, From Wimbledon to Wherever in Surrey You Are

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. We're based in Wimbledon Park, and Surrey sits right alongside the rest of our South West London practice, handled by the same two people throughout.

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