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.

Planning Permission Architects London

Design United Studio offers planning permission and permitted development applications as a service in their own right, whether or not we're designing the project itself.

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Handled From Submission To Decision

What This Service Actually Covers

We handle the planning side of a project from start to finish. That means checking whether permitted development applies before anything is submitted, preparing and lodging the application itself, liaising directly with the council's planning officers while it's under consideration, and managing an appeal if a decision doesn't go your way.

Permitted Development Or Full Planning Permission

Permitted development lets certain extensions and alterations go ahead without a full planning application, provided they stay within set limits on size, height and position.

Anything outside those limits, in a conservation area, or on a listed building, needs full planning permission instead. Getting this call wrong at the outset is the single biggest cause of delay we see, which is why we check it first rather than assuming.

Preparing And Submitting Your Application

A planning application is more than a set of drawings. It needs the right supporting statements, accurate site plans, and submission in the format your local council actually expects, since requirements vary between boroughs.

We prepare and submit the full application package, so nothing gets bounced back on a technicality.

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Liaising With The Council On Your Behalf

Once an application is in, planning officers often come back with questions, request amendments, or want a conversation before making a decision. We handle that liaison directly, rather than you fielding calls from a case officer about technical points you didn't design.

In our experience, this direct contact is often what moves a stalled application forward.

What Happens If Your Application Is Refused

A refusal isn't always the end of the road. We review the reasons given, and where there's a genuine case, we handle the appeal process on your behalf, including revised submissions or a formal appeal to the Planning Inspectorate if that's the right route.

Local Knowledge That Actually Helps

Why Design United Studio

Jürgen Kuppers and Kirana Laonipon lead planning applications here as RIBA and ARB registered architects, with local knowledge of planning departments across Wimbledon and South West London built up over more than a decade.

That local familiarity, knowing which planning officers care about which details, is often what separates an application that sails through from one that stalls.

Portfolio

Our Track Record

2

Hands-On Team

100+

Projects

99%

Planning Approval Success Rate

10+

Years in Practice

Hear From People We've Worked With

"We'd been told our extension would need a lengthy appeal. Jürgen found a way through with the council directly and we had approval within weeks."

DANIEL K.

"Kirana caught an issue with our proposal that would have got it rejected, and fixed it before submission. Worth it just for that."

AMARA S.

"Professional from the first meeting to the final snag list. Our two storey extension came in on the timeline they gave us, which we didn't expect after hearing other people's horror stories."

Priya K.

Straight answers before you call