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 Streatham

Streatham's Victorian and Edwardian terraces cover a genuinely wide range, from compact two-bed cottages to the substantial three-storey Queen Anne-style houses around the old Streatham Park Estate. Design United Studio, led by director Jürgen Kuppers, designs across that whole range rather than specialising in one end of it.

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A Borough of Genuinely Different House Sizes

Why a Streatham Cottage and a Streatham Park Villa Need Different Briefs

A compact cottage extension and a full reconfiguration of a three-storey Streatham Park villa are barely the same kind of project, even though both sit under the same "Streatham" postcode. We start each from what the house actually needs, rather than applying a standard-sized brief to houses that were never standard-sized to begin with.

The Queen Anne Character of Streatham Park and Garrads Road

The Streatham Park and Garrads Road conservation area preserves a distinctly Queen Anne character, decorative brickwork, terracotta detailing and generous bay windows, that dates back to the 1880s. An extension here needs to match that level of detail convincingly, not just the overall massing.

Extending a Victorian Terrace Near Streatham High Road

The Streatham High Road and Streatham Hill conservation area covers a busier, more town-centre stretch, with mansion blocks alongside the terraces.

Kirana Laonipon, our Part II architectural assistant, designs rear extensions and loft conversions here with that livelier streetscape in mind, so the addition still reads as part of a Victorian terrace rather than competing with its surroundings.

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Streatham Common's Conservation Area

Streatham Common has been the borough's green heart for centuries, and the conservation area built around it protects the relationship between the open space and the buildings that face onto it. Properties near the common are considered with that setting in mind, and we account for it from the earliest sketches.

Working With Lambeth's Planning Team

Streatham falls within the London Borough of Lambeth, a different authority from the Merton-run boroughs we cover elsewhere in South West London, with its own local plan and conservation area profiles. We prepare Streatham applications to match what Lambeth specifically expects, rather than carrying assumptions over from a different council.

Big-Practice Experience, Small-Studio Attention

The People You Meet Are the People Who Design It

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.

Streatham is one of eighteen areas we cover as part of our wider South West London architects practice. There's no handover partway through, the people who scope a Streatham project are the ones who finish it.

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