Unsupported browser

For a better experience please update your browser to its latest version.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We use cookies to personalise your experience; learn more in our Privacy and Cookie Policy. You can opt out of some cookies by adjusting your browser settings; see the cookie policy for details. By using this site, you agree to our use of cookies.


‘Concrete House’ extension completed by Daykin Marshall


The south London-based practice has framed a sunny courtyard garden with an extension in Dulwich

This £340,000 project features a reconfigured ground-floor plan and in-situ concrete extension to a detached house. Made from a concrete mix using pulverised fuel ash (PVA) to reduce the cement content, the extension consists of a repositioned kitchen, study space, and TV and dining room.

The client wished to take full advantage of the extension’s south-east facing aspect, and so the concrete structure acts as a heat sink to prolong the daytime warmth into the evening, while its stepped form encloses a courtyard garden which is hidden from overlooking. Internally it is lined and insulated through a simple softwood timber-box structure.

ngut 1430 daykin marshalll 126

ngut 1430 daykin marshalll 126

Architect’s view

Our work enjoys playing with mass and solidity, and notions of longevity, so in-situ concrete, done well, was something we wanted to experiment with. Achieving a consistent, smooth finish for the concrete wall was the most technically challenging part of the design, as well as the biggest concern for the client. We worked closely with the contractor to build precise formwork, and developed an exacting specification for the mix and pour with concrete specialist David Bennett. Thirty per cent PFA was included in the mix as a portland cement replacement. This reduces the quantity of cement required and diverts PFA, an industrial waste product, away from landfill. 

The concrete is strong and monumental, but also smooth like fine marble, ‘soft’ to the touch even like suede. It provides a powerful, yet calming, backdrop to the intense greens and delicate foliage of the garden – especially two beautiful mature trees, which have been carefully retained close by. The garden design was developed in collaboration with Sam Butler. 

There was a wonderful moment in construction when the formwork was struck and the only element present above ground was the stepped concrete wall standing in space. Walking around this ‘screen,’ interior and exterior spaces were blurred, one being an inversion of the other. This feeling remains tangible after completion when looking or moving from inside to outside and back again through the stepped plan. The intensity is accentuated in the use of reflection through glazing and mirrors.

Mark Marshall, director, Daykin Marshall Studio 

ngut 1430 daykin marshalll 049

ngut 1430 daykin marshalll 049

Client’s view 

Our house is a rather austere 1950s property and Daykin Marshall Studio respectfully echoed this in an ostensibly simple yet powerful, and above all calm, design. The orthogonal concrete is juxtaposed against an informal mature garden and the contrast serves to enhance both. Precision in the detailing of what is ultimately a very restrained design was paramount, and the resulting balance adds to the overriding sense of tranquillity the extension lends to our house. 

Ground floor plan

Ground floor plan

Project data

Start on site  September 2016
Completion December 2017 
Form of contract Traditional – JCT Minor Works with Contractor’s Design 2016
Construction cost £340,000
Construction cost per m£2,720
Architect Daykin Marshall Studio 
Client Private
Structural engineer Momentum Consulting Engineers
Landscape consultant Sam Butler Garden Design
Concrete consultant David Bennett Associates
Main contractor Bespoke Construction & Glazing


Readers' comments (4)

  • The walls of the existing house appear to be either painted or freshly rendered white, and it'll be interesting to see how the new concrete walls weather, in comparison.

    Unsuitable or offensive? Report this comment

  • Industry Professional

    £340,000 !!!!!! That seems really poor value for money - That would have built a new house!

    Unsuitable or offensive? Report this comment

  • I have to agree that the cost is astronomical for such a basic design.
    Don't architects have a fiduciary responsibility to their clients?
    Someone got screwed and someone did the screwing.
    Dumb client; inexperienced designer; smart contractor - there the fault must reside.

    Unsuitable or offensive? Report this comment

  • Very Beautiful House. Concrete definitely gives it a character and solidity. A lot to learn from this.

    Thanks & Cheers,

    Unsuitable or offensive? Report this comment

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions.

Links may be included in your comments but HTML is not permitted.

Related Jobs

Discover architecture career opportunities. Search and apply online for your dream job.
Find out more