Trade Archives - CDI

We’ve a new model down at Swindon!

May 18, 2017

One of the great benefits that you get from introducing Lewis Deck into a residential development is the option to install a wet room floor into bathroom/ en-suite areas with extreme ease compared to other flooring systems as well as maintaining one solid concrete slab in the room reducing the possibility of leaks from a number of different materials being used to create the floor.

When we talk about the benefits of what Lewis brings to a project this seems to be one of the benefits that seems to get lost in conversation with people generally wanting the acoustic or solid floor improvements before anything else. However, over the last few months (with us spending a lot of time at trade shows) both myself and Chris have been having more and more conversations with people looking to add that little bit extra to their bathroom areas by having wet rooms rather than traditional bathroom and shower areas.

This posed us a bit of a dilemma, how do we get the point across to people that Lewis is the material of choice when it comes to thinking about upper floor wet rooms.

The answer, Swindon.

As has been mentioned in a number of different places on this website we have a permanent stand at the National Selfbuild and Renovation Centre in Swindon.

This is it!!

SAMSUNG CAMERA PICTURES  (and this is what the stand looked like last week)

Stand E171 was, once upon a time, shared between ourselves and Gyvlon, the screed manufacturer. Earlier this year however, Gyvlon decided that they no longer wanted to share the stand so we took over the whole (even though it’s only small) thing!

With us being based in the north east we needed a reason to go down to Wiltshire and replace the bottom model with something new so this was the perfect time, and the perfect reason, to go down and update what we have down there.

So, a couple of weeks ago we set the plan into motion. First of all we needed old timbers to replicate joists in a house. Chris found the local timber reclamation yard and off we went to pick up a few bit of wood from it. When we got there it was closed!! Who knew Google told you when businesses were open and closed!

We eventually got going and over the next week or so the new model started to take shape.

One of the things that we wanted to do with this new model was show people how easy it is to install a drain into the Lewis and then create the falls to allow the room to function as it should. With that in mind below you’ll see a number of photos showing you how easy it is to install a drain into Lewis then create the falls!!


Firstly cut a hole through the steel deck large enough for the waste pipes to fit through. I say large enough seen as though the first time we did it the hole was just too small!

At this point the waste pipe can be inserted into the deck and the drain fixed into position within the drain as below.

20170503_110446 20170503_111412


Once the drain is in place ensure that the whole connection is sealed and that the hole that was cut into the steel is also sealed completely. This then ensures that no concrete screed leaks through any gaps when it is poured.

Lewis Deck and underfloor heating

Lewis Deck and Underfloor Heating

February 28, 2017


SE5 Architects Project
Lewis Deck as the separating compartment floor for acoustic and fire separation and including underfloor heating

The Lewis Deck system provides solutions for acoustics, fire, high loads, underfloor heating and wet rooms, it can achieve all of these simultaneously with relatively simple build ups. All of these aspects will be touched on, but this paper sets out to discuss the case for concrete/screed floors with underfloor heating “upstairs.”

This is a system that allows the introduction of a suspended lightweight concrete or screed floor into the upper floors of buildings on top of beams or joists.


Lewis Deck – the system

Lewis metal deck and underfloor heating
Lewis metal deck and underfloor heating

Lewis Dovetailed metal decking is a steel sheet that is rolled to form a dovetailed profile, this is then used to span over the top of joists and a concrete or screed is then poured on top. The Lewis® acts initially as permanent shuttering for the concrete, being able to bear the weight up to some reasonable joist centres, however, once the concrete has cured the Lewis Deck then acts as reinforcement. This composite action that gives the system many of its advantages including loadbearing and stiffness for such a thin concrete construction, just 50mm in most situations.

Lewis Deck and underfloor heating
Lewis, under floor heating pipes, screed.

For acoustic floors it is simply a case of isolating the Lewis Deck and concrete from the joists and surrounding walls by the use of a simple resilient strip, the strip also acts as the expansion joint around the edge of the floor. The Lewis Deck system has been used in many acoustic separating floors including new-build and conversion, from standard domestic apartments to music venues under apartments, recording studio floors, cinema floors and just where the added value of a very quiet floor is desired.

The fire solution is a combination of the overall build up and has been tested up to 120minutes, therefore suitable for many applications.

For wet-rooms it is simply a case of using a suitable concrete and an appropriate simple floor to wall edge detail. Falls and drains can also be built-in for that true wet-room experience.Note: concrete/screed from this point on will be referred to as simply concrete, but the term concrete or screed can be used interchangeably within this document)

The video compares the Lewis Deck and Thermio+ screed (top left) against aluminium spreader plates (top right).  On the bottom the comparrison is a typical ground floor showing the Thermio+ screed (bottom left) against concrete (bottom right).

underfloor heating pipe being laid on Lewis Plate

Another mention in the house building press

February 28, 2017

The Lewis Deck has been picked up by a number of magazines over the years, here is the latest mention in a discussion about underfloor in the Real Homes Magazine:

Underfloor heating: your questions answered

Underfloor heating: your questions answered

Thinking of installing underfloor heating? Real Homes has posed your most-asked UFH questions to industry experts

Wet vs dry systems

As electric systems are installed directly under the floor covering, and work independently from your central heating system, they are particularly useful for one-room installations or where the sub-floor level is already set. The wire or matting systems are very thin (around 3mm) and shouldn’t cause problems with differing floor levels – thus creating little disruption to the existing room.

Wet systems circulate warm water through plastic pipes installed underneath the floor and are connected to the main central heating source. This system tends to work best when the pipes are embedded in a screed, as this helps dissipate the heat, so it is suited to new floor constructions where the sub-floor can accommodate the pipework and cement screed. Wet systems are therefore more likely to be used in new-builds and extensions or during major renovation work.


Wet underfloor heating (UFH) systems generate temperatures of around 40°C to 65°C, meaning that the actual floor temperature will be on average between 23°C and 32°C. This is actually lower than a standard radiator, so your household heating costs should be reduced over time.

Ease of control

Specialist UFH controls are vital to ensure comfort, responsiveness and energy efficiency. UFH takes longer to heat up and cool down compared to radiators, so to overcome this time lag, programmable controls are essential.

For households with irregular or limited occupancy and for holiday homes, it is useful to have remote control so that you can turn it on an hour or two before arriving. Remote control is also useful if you forget to turn the heating off.

Getting the right insulation

Underfloor heating will always be more efficient and cost-effective when fitted above insulation, as this reduces downward heat loss and forces heat up into the room where it is wanted. In new-build homes and extensions, floor insulation will be incorporated to meet Building Regulations, while on refurbishment projects insulation can usually be added.

Taking up existing floorboards to add insulation between the joists is fairly straightforward. Adding insulation to a concrete screed floor, however, will mean that the height of the floor is increased so skirting boards and doors will have to be adjusted accordingly. We always recommend speaking to a reputable company, as they will be able to offer advice based on the individual characteristics of your home.

Choosing flooring

Solid floors, including stone, porcelain, ceramic, terracotta and slate are ideal, as they tend to have great thermal conductivity and will provide good heat output when it comes to underfloor heating. If you prefer timber flooring, always check with your supplier to ensure it is suitable for use with underfloor heating, or consider engineered timber boards that, due to their construction, tend to be more stable during changes in temperature.’

In both cases, bear in mind that temperatures shouldn’t exceed 27°C. Most top-of-the-range laminates can also be used with underfloor heating, as can all carpets — although you may find heat output is slowed down a little, due to the combination of carpet and underlay.

Potential faults

The main cause for concern for many prospective buyers of warm water underfloor heating is what to do if the pipes leak. However, unless a nail is accidentally put through them at some stage, this simply does not happen. There are no joints in the floor and the various pipes used are designed and tested to have a 50-year life expectancy at temperatures and pressures that exceed those required by the system.

If accidental damage should occur, then individual pipes can be pressure tested to locate the correct one. In timber floors, the pipe can usually be exposed to allow for repairs, while screed floors will need to be excavated to uncover the pipe.

Choosing the right system

It’s particularly effective for large open-plan spaces – particularly those with high ceilings – as the entire floor radiates heat upwards so you benefit from warm feet and even room temperatures. This radiant heat also means reduced draughts, moisture levels and airborne allergens.

Typically underfloor heating is more than enough as a stand-alone form of heating. However, its capabilities will often be dictated by other factors, such as floor coverings and a building’s insulation levels (especially walls and windows). This is why heat-loss calculations are so fundamental, as having looked at a building’s individual thermal performance they will tell you how much heat you need to generate.

For example, a poorly insulated room with lots of glazing may not heat fully when it is cold outside (which means additional insulation or supplementary heating may be necessary). Floor coverings also play an important role. Normally, stone and tiles are excellent options, as are carpets with suitable tog ratings. If you’re keen on timber, however, remember it has a lower temperature tolerance.

Underfloor heating vs radiators

Where cost is an issue, the expense of installing underfloor heating may outweigh the advantages, especially if it involves removing concrete floors and re-screeding. In houses not occupied during the day, underfloor heating’s slow warm-up and cooling time (which can be up to four to six hours) may not suit you.

‘A combination of both systems can often be the best answer for many homes, as radiators can be easily incorporated into an underfloor system. A good compromise is to install underfloor heating on the ground floor, with radiators upstairs to accommodate the different requirements for living and sleeping spaces, especially as many people still want heated towel rails in their bathrooms.’


A new chapter for CDI-ICM

August 17, 2016

A very warm welcome to the beginning of a new chapter for CDI-ICM. Today we take a very big leap into the 21st century and post our first blog to go alongside the creation of our new website ( The plan is to post updates at regular intervals keeping you updated about what we are up to and what we are involved in. We also get asked some weird and wonderful questions around our products so we’ll answer some of them here as well just in case you’ve been thinking of them too but have been too afraid to ask.
But for today who are we and why are we here?

We’re a small family business, based in the north-east of England, behind building products such as FastSlab, Max4, Lacomet and of course our multi Oscar winning floor system Lewis Deck. Our philosophy is to help solve problems and offer products that enhance and improve projects from the whole spectrum of the construction industry no matter of size.

Today however I’m going to park what we do so I can introduce you us, so if you do get in touch you’ll kind of know who we are already, a handwritten ice breaker if you will.

Firstly, our Commander in Chief, our Managing Director, former army Captain (just not with the same singing ability as James Blunt) Mr Chris Holt. Chris initially joined the business back in 2007 when it was still in its old form of Ian Larnach Associates. It was Chris’s idea to move away from the consultancy side of the industry into what we are now which is why he wears a crown while sitting at his desk! Chris is a technical genius where our products are concerned so he’s your man if you have any queries regarding acoustics, loadings or any of the dark arts involved with our range.

Me, I’m Paul. I’ve only been a director at the company since the beginning of the year after being drafted in following my old man’s (Ians) retirement through ill health (in reality his golf handicap was starting to creep up so needed more time on the course to sort it out). It feels like I’ve spent my whole life being in and around the construction industry and after initially starting out as a junior QS I climbed up the ladder to eventually project manage some amazing multi-million pound projects.

Finally, the real boss in the office, our Office Manager Barbara. After being married to Ian for 40 odd years she can put up with anything thrown at her and quite often does. Grown men have been known to cry when a call is put through to them from Barbara regarding an unpaid invoice! She is the glue that holds the company together and is the happy voice at the end of the phone when you call in to us.


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Trade Archives - CDI