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 Raynes Park

Raynes Park is really two towns in one: Victorian and Edwardian terraces radiating out from the station and town centre, and the 1930s semi-detached streets around Grand Drive, with their bay windows, hipped roofs and gabled porches. Design United Studio, led by director Jürgen Kuppers, designs extensions that read as though they always belonged, whichever era of house you're in.

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A Town Built in Two Distinct Waves

Why a Grand Drive Semi Needs a Different Approach to a Victorian Terrace

The interwar semis around Grand Drive and Motspur Park share a distinct Metroland character: canted bay windows, hipped tile roofs and a gabled porch, all fairly uniform along the street.

Closer to the station and town centre, the housing stock is older, mostly Victorian and Edwardian terraces with their own proportions and detailing.

An extension that works on one doesn't automatically work on the other. Jürgen designs each to match the specific rhythm of its own street, rather than applying one house style across the borough.

Cannon Hill Common and Prince George's Playing Fields Shape What's Nearby

A lot of Raynes Park gardens back onto or sit close to Cannon Hill Common or Prince George's Playing Fields, and mature trees near a boundary can be covered by a Tree Preservation Order.

We check this early, since it can affect where a rear extension or garden room can actually sit, not just what it can look like.

Extending a Raynes Park Semi Without Losing the Bay and Gable

The canted bay and gabled porch are what give a Grand Drive semi its identity. Kirana Laonipon, our Part II architectural assistant, designs rear extensions and loft dormers to keep those proportions intact, so the addition sits with the house rather than against it.

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Getting a Semi-Detached Extension Right First Time

Semi-detached houses share a party wall with a neighbour, which means a Raynes Park project almost always involves a party wall agreement alongside the planning application. We handle both together from the start, so the build isn't held up waiting on a notice that should have gone out months earlier.

Working Within Raynes Park's Conservation Areas

Parts of Raynes Park, including streets around Lambton Road and Dunmore Road, sit within conservation areas, and the West Wimbledon conservation area borders the area too. That affects what can change on the front of a property without planning permission, and it's one of the first things we check on any Raynes Park project.

The Studio Raynes Park Families Come Back To

Two People, Every Raynes Park Project, Start to Finish

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.

Raynes Park is one of eighteen areas we cover as part of our wider South West London architects practice, with the same two people handling a project from first sketch to sign-off.

Portfolio

Our Track Record

2

Hands-On Team

100+

Projects

99%

Planning Approval Success Rate

10+

Years in Practice

What Our Clients Say

"We're on a Grand Drive semi and were worried an extension would look bolted on. It doesn't, it matches the bay and the roofline like it was always there."

HELEN P.

"The party wall side of things worried me more than the design. They sorted the agreement with our neighbour before it became a problem."

"Our garden backs onto Cannon Hill Common and I didn't know a tree order could affect us. Good to have it flagged early rather than after the drawings were done."

DAVID R.

SOPHIE M.

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