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Castelnau architects.
Britain's No. 1

Barn Elms may be popular, but wait until people see your new home extension, designed by Trustpilot's highest-rated UK architectural practice.

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A planning team staffed by ex-council officers

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Richmond upon Thames planning application stats

Our planning permission win rate for the Richmond upon Thames area is as follows:

Richmond upon Thames


UK Average


Resi's planning consultant

Danielle Price

Former Wigan Council Planning Officer
Richmond upon Thames's planning officers

Matt Bayley, Roberta Henriques, Jackson Morgan, Jeremy MacIsaac, Georgia Nicol, ...

135 Number of applications
6 - 366 days Submit to complete time
120 Granted applications
15 Refused applications
8w 5d Average decision time
See if you qualify for Permitted Development

We've had 120 planning applications approved in Richmond upon Thames

First floor Balcony

Castelnau , SW13 9ER

29 Jan '20

Whole house Internal alteration

Merthyr Terrace, SW13 8DL

09 Oct '19

Loft Outrigger dormer

Lillian Road, SW13 9JF

11 Jan '23

Ground floor Rear

Castelnau, SW13 9RP

14 Feb '23

Ground floor Rear

Castelnau, SW13 9RP

01 Apr '22

Basement Main house

Melville Road, SW13 9RH

15 Oct '21

Basement Main house

Melville Road, SW13 9RH

31 Oct '22

Basement Main house

Melville Road, SW13 9RH

03 Mar '22

Ground floor Side infill

Rainville Road , W6 9HA

19 Feb '21

Loft Outrigger dormer

Langthorne Street, SW6 6JX

17 Jun '20

Ground floor Rear

Crabtree Lane, SW6 6LN

09 Jan '24

Ground floor Rear

Crabtree Lane, SW6 6LN

27 Nov '23

The above are all actual Resi projects in and around Richmond upon Thames. Projects have been anonymised in accordance with GDPR data regulations.

Average construction costs for the Castelnau area

In the last year, the construction costs we've seen for the Castelnau area are as follows:



Side Infill




First Floor


Try our Construction Cost calculator

Here's just a few projects we've done near Castelnau

The Avenue

The Avenue

Ground floor rear
Completed 2020
Planning authority Richmond upon Thames

Why people near Castelnau love Resi

Over 8400 homeowners have trusted Resi with their home extensions — that’s more than any other architect in the UK.

Came across Resi in 2017 and have to say their service has been exceptional on all fronts. Prompt...


Ground floor Rear

Alexander Ell

Used to do initial design phase for a loft conversion and internal remodelling. Very helpful in t...


Loft Main dormer

The best out there

I have been with Resi now for over a year and they have looked after me well. They have helped me...


Two storey Side

Luisa Wolf

The planning permission (1st of that kind on my neighbourhood) for the extension of my house was...


Loft Main dormer

Peter Spence

So easy! Previous experience with face to face architect not great. But Resi are so easy to deal ...


Ground floor Rear

Resi are a great investment!

Resi have been great. We knew we needed help and saw a couple of “all in” firms before we found R...


Ground floor Rear

Patricia Ladly

I had my reservations about getting design plans on-line but the whole process has been very prof...


Loft Main dormer


Very impressed with the service and the attention to detail to my requirements. the team were ver...


Ground floor Rear

Freddie White

Great service, easy to use and very fast results, highly recommend. Easy process from start to fi...


Whole house New build

Absolutely Brilliant!

I was recommended to use Resi by a friend of mine. I found the whole process an absolute dream. F...


Ground floor Side infill

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Be more likely get an 'A-okay' with our 90% planning approval rating.

A dedicated Account Manager to help you through the process's more stressful moments

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Get intro'd to vetted builders who've been around the (extension) block before

We use bleeding-edge new tech like laser scanners and 3D modelling software

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Builders we work with in Castelnau

Home Republic Limited
7 reviews
Covers Castelnau
39 Resi projects
Fittra Construction
Covers Castelnau
4 Resi projects
N-Vico Ltd.
3 reviews
Covers Castelnau
8 Resi projects
Kovacs Construction Ltd
7 reviews
Covers Castelnau
31 Resi projects
4 You Residential Ltd
Covers Castelnau
6 Resi projects
Lifestyle London Design & Build Ltd
2 reviews
Covers Castelnau
7 Resi projects
Check out our vetted builders