Do you need an architect to get planning permission in London?

Short answer: no. For most home projects you are not required to hire an architect to apply for planning permission, and anyone can submit an application. The better questions are what actually moves your odds, how long you will wait, and what a professional genuinely changes. To answer those with numbers rather than folklore, we analysed 630,583 planning applications across 32 London planning authorities, with decisions up to July 2026.

Every number below comes from the same public planning records that power our council research pages. These are real applications and real decisions, not estimates. Where we quote an approval rate, we count only decided applications (approved or refused) from the last five years, and we show the sample size behind it.

Your borough moves the odds more than you might think

For a typical home extension, the borough you live in is the single most visible factor in the public record, which is what the chart above shows. Among the 18 boroughs with at least 1,000 extension decisions in the last five years, Hammersmith and Fulham approved 92.7% of them (2,162 decided) and Camden 91.5% (3,184 decided). At the other end, Greenwich approved 66.7% (1,093 decided) and Brent 71.5% (2,188 decided). That is a 25.9-percentage-point gap for the same kind of project, depending on where the house stands.

A lower rate is not destiny and a higher one is not a formality. Every application is judged on its own merits, and boroughs differ in housing stock, conservation areas and policy. It does mean the folklore you hear at dinner parties is usually calibrated to somebody else's borough, though. Someone who has taken projects through your council recently will know its patterns long before you find them out the hard way.

What London councils approve, by type of project

Across London over the last five years, straightforward alterations approve at the highest rates: replacement windows and doors at 91.9% (7,825 decided) and basement works at 90.1% (8,288 decided). The classic home projects cluster in the low eighties, with rear extensions at 82.7% (31,683 decided), loft conversions at 82.5% (15,852 decided) and side extensions at 81.9% (9,207 decided). The genuinely contested category is change of use, at 70.9% (5,142 decided). Nearly three in ten of those are refused.

How long you will wait

Among the same 18 boroughs, the typical (median) extension decision took between 41 days (Barking and Dagenham) and 75 days (Hammersmith and Fulham) over the last five years, which is roughly six to eleven weeks. One detail worth knowing: the boroughs that approve the most are often the slowest. Hammersmith and Fulham and Camden sit at the top for approvals and near the bottom for speed, at medians of 75 and 71 days, while Redbridge decides extensions in a median of 42 days with an 80.8% approval rate (2,368 decided). A long wait is not a bad sign.

The trend is also kinder than the folklore. Of the London applications decided in 2017 in our records, 82.8% were approved (35,574 decisions); in 2025 it was 88.7% (23,379 decisions). Part of that shift is real and part reflects which decisions councils have published recently, so treat the direction as encouraging rather than exact.

So do you need an architect?

Here is the honest version of a statistic you may see quoted elsewhere. In the last five years, 27.9% of decided London applications named a professional agent on the application form, whether an architect, architectural designer or planning consultant (37,563 of 134,742 decided applications). Those applications were approved 83.2% of the time; applications without a named agent, 88.2% of the time.

Read carelessly, that looks like a reason to skip the professional. It is nothing of the sort. The two groups are not filing the same projects: homeowners tend to handle the simple, well-trodden cases themselves, while professionals are brought in for the awkward sites, the conservation areas and the ambitious designs. Our data cannot separate cause from case mix here, and any guide that promises hiring an architect will move your approval odds by some exact percentage is not being straight with you.

What a professional demonstrably changes is the project you dare to ask for, and the quality of the application that asks for it: drawings a case officer can trust, a design that answers policy questions before anyone raises them, a considered response when the council pushes back. Just over one in four London applications is shepherded through this way. Homeowners who hire seem glad they did, too. The 42 London architect practices with published reviews in our directory average 4.9 out of 5 across 2,310 reviews.

How to check an architect before you hire

• Ask whether they are registered with the Architects Registration Board. "Architect" is a protected title in the UK and the ARB register is free to search; chartered practices also appear on the RIBA register.
• Ask which London councils they have taken projects through recently, and for addresses of nearby work you can look at from the street.
• Read their reviews on more than one site, not just the one they link to. Patterns across sources are harder to fake than a single glowing page.
• Check the business itself before money changes hands: how long it has traded, and whether its records look current.