For this reason it is mainly used in new-builds and either a sand and cement screed (4:1 mix) or a pumped screed system (anhydrite etc) is used over the top. Fine or heavy concrete or Polymer modified screeds can also be used.
There are three options for installing into a solid floor. The red panels are the most popular as they are so easy to deal with. They overlap to reduce the amount of cutting you will have to do and they hold the pipe securely reducing the need for clips and staples. They also ensure any bends have the correct radius and are not too tight.
All three methods are used on top of pre-installed insulation. This keeps the heat within the floor and prevents it being lost below the room. Whichever method you choose to secure the underfloor heating pipe you should take great care that there are no unfixed lengths of pipe as these could float to the surface when the screed is poured on top.