The Blue House with Durisol ICF Blocks - CDI
Front if the Blue House
The Blue House with Durisol ICF Blocks

One of the more interesting aspects of working with self-build projects is the varied and, at times, very different approaches that are taken when it comes to the design of a new property. This property is no exception.

Built on a self-build development site at Graven Hill in Bicester, where every property is different, it utilises a number of different design styles and is constructed from an ICF system called Durisol Blocks.

See this house and the one next door that both used the Lewis Deck system on Grand Designs: The Street

Durisol is the original ICF units. They were introduced to the UK in 2005 having been successfully used for build projects across mainland Europe for over 70 years.

Their wall form units are quick and easy to construct. The pre-insulated interlocking ICF wall form units are dry stacked together to form the walls. The wall form units are then in-filled with concrete to form a monolithic structural walling system. Unlike other ICF wall form units, there is no need to prop the walls during construction as the weight of the blocks holds them in place. All of their products are manufactured in South Wales from recycled cement-bonded wood fibre material.

Lewis/ Durisol
Lewis Deck/ Durisol
Durisol Blocks
Durisol Blocks

One of the benefits from using the Durisol system is that you can use the same concrete that is used to fill the wall blocks as the screed for the Lewis Deck. As with all other concrete/ screeds it only needs to be 50mm thick without underfloor heating pipes or 52mm with underfloor heating pipes. This could potentially help with the speed of build as it is possible to do two jobs at once!

Tamping Concrete
Tamping Concrete

Durisol Blocks are extremely easy to install and you can learn how to install them yourself.  Durisol hold regular training courses throughout the year. The courses are designed to show you how to build with Durisol and answer any queries. If you’re thinking of building with Durisol they provide the perfect opportunity to find out more about their product.

These training courses are often at the National Self-Build and Renovation Centre in Swindon where we also have a permanent stand and where we attend every exhibition that the centre puts.

If you are thinking about building your own property using this type of system with Lewis Deck means you can actually build it yourself. Well, maybe not all of it!!

Lewis Deck System Page

We used Lewis Decking in this new build in order to a achieve a feeling of solidity, increase the thermal mass, and reduce the sound transmittion from footfall. It proved to be a very simple system to lay and then subsequently provide a solid sub-structure on which to attach our underfloor heating pipes, prior to the application of the concrete.

Terry Waite

As with most new properties these days the 1st floor joist were timber “Posi-Joists” laid at 600mm centres. This allowed the services to run through the joists and reduce the overall depth of the floor. 6mm resilient acoustic strips were then stuck to the top surface of the joists and the Lewis Deck laid loose on top, with 16mm underfloor heating pipes and a 52mm concrete screed poured onto the deck. This maximised the performance of the floor and gave Mr & Mrs Brown-Waite what they desired.

In addition to the underfloor heating benefit of using the system, it also provides a very high level of acoustic and fire separation and in this project was used in the bathrooms to provide a true wet-room experience with the drain set in one continuous layer of concrete and the falls down to the drain formed in the concrete itself.  It is then a simple job to waterproof the floor to wall joint and waterproof the top of the concrete and walls with a proprietary waterproofing system.  More information about wet-room floors can be found here.

Lewis/ Posi-Joist
Lewis Deck and Posi-Joists
Lewis on a Mezzanine
Lewis Deck on a Mezzanine

Mr & Mrs Brown-Waite

Mr & Mrs Brown-Waite

Here is a link to the Grand Designs Show write-up in the Times where both Terry and Olwen’s “Blue House” and their neighbour Lynn’s contemporary cottage with oast-inspired roundel jutting out of the roof are the subject of the 1st show to be aired in the series.  Both houses utilise the Lewis Deck in their 1st floors.

And a link to the introduction to the Grand Designs series by Kevin McCloud



We are on the Graven Hill Trade Directory


Ask CDI a Question

  • Q

    What are the Lewis Deck sheet sizes?


    Q: What sheet sizes are held in stock for delivery within a few days after order? A: We stock 2500mm and 1300mm sheets.  These are all 630mm wide and 16mm deep.  Deliveries are made via the pallet network directly to site.  The smaller sheets are aimed at small bathroom renovation projects and can be supplied in small numbers via TNT. 2.5* and 1.3m sheets allow for the 100mm overlap to occur over a joist, with joist centres being either 300mm, 400mm, 600mm, 800mm*, 1200mm and 2400mm*. (*2.5m sheet only) For larger projects we are able to produce bespoke sheet sizes if required, please get in contact to discuss other options for sheet sizes.

  • Q

    Why don't my Lewis sheets interlock like they do in the video?


    Q: Why don't my sheets interlock like they do in the video? A: The sheets have two sides (one printed, one plain), the dovetails on either side are different widths, it is then necessary to alternate the sheets print up and then print down.


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The Blue House with Durisol ICF Blocks - CDI