Preparing for Underfloor Heating

7th August 2015 0 By ThermoUFH

Before commencing the install of your Underfloor Heating it is important that a number of points are given careful consideration;


Your chosen floor finish can massively affect the heat output you will get from your Underfloor Heating System. Heat outputs for Underfloor Heating are measured in W/m² (watts per square metre) – these can be affected considerably by your final floor finish. An example of outputs based on a pipe in screed system, with a water flow temperature of 50°C are:

Tile                                                         95W/m²

Carpet Tiles / Laminate                       69W/m²

Carpet & Underlay (1.5TOG)               55W/m²                                                                                                                                        

As you will see from the example above Underfloor Heating System works best with tiles. In a well insulated modern building you will get enough output from a well designed Underfloor Heating System using carpet. It is recommended you have heat loss calculations prepared to ensure the Underfloor Heating will give enough heat output with your chosen floor finish to heat your home. It is also worth noting that some timber flooring manufacturers recommend a maximum floor temperature of 27°C – if this is the case we can supply a probe to install in the floor to prevent the floor ever exceeding this.


Underfloor Heating can easily be added to a building whilst it is under construction, however, it can also be retro-fitted to existing buildings. ThermoFloor Supplies offer a wide range of Retro-Fit options for renovation projects. These systems include;

Foil Faced Overlay Boards (minimum of 25mm)

Spreader Plate Systems

ThermoFloor Variokomp (minimum of 18mm)

Pugg Screed Systems                                                                                                                                                                                      

For advice on any of our retrofit solutions please contact a member of our team to discuss your options.


The installation of a wet Underfloor Heating System complete with insulation and screed can see floor heights increased by at least 100mm. It is important that this is allowed for at the design stage of the project so that the concrete subfloor can be installed at the correct height. If this build up in floor height is not possible, ThermoFloor Supplies offer a variety of retro-fit solutions which include micro-pipe for wet systems.


Insulation & Screed work together with the floor covering to determine the outputs and response times of underfloor heating systems. Insulation is important beneath your screed to prevent downward heat losses and increase the overall efficiency of your system. The screed works as a thermal mass to hold the heat generated by the underfloor heating pipework. Some of our retrofit systems also use a thermal mass for example our Variokomp Underfloor Heating System.

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