Lewis Deck and Underfloor Heating
February 28, 2017
Introduction
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 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.
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).