Floor Coverings and Insulation

Underfloor Heating Floor Construction

Floor Coverings
A range of floor coverings can be used with UFH, however, thought should be given with regards to which is the most suitable solution. As the resistance of the floor covering increases, the water temperature that flows around the system must also increase, to overcome this resistance of the floor covering. For this reason, ideally a covering such as stone, marble or ceramic tiles would be used, however other floor coverings can be used. The following section gives a brief over view of some of the choices available and also the considerations that are required. We would always recommend contacting the manufacture of the covering you intend to use, to ensure compatibility with UFH systems.

Floor coverings with a high thermal resistance should be avoided with UFH systems. Any floor covering placed on top of a screed should have a TOG rating of, ideally, less than 1.0 but should never exceed 2.5. Note, the TOG rating is equal to 10 times the thermal resistance. Eg If a carpet has a TOG value of 0.8 then it will have a thermal resistance of 0.08 m²K/W. You can down load further information on floor coverings from Downloads.


Floor Insulation
It is a legal requirement that insulation is fitted within the floor. The insulation should comply with the requirements stated in Part L of the Building Regulations (England and Wales) regardless of whether UFH is installed or not.   The relevant Building Standard codes for other countries are as follows:

  • Northern Ireland – Technical Booklets F (conservation of fuel and power) and G (sound)
  • Republic of Ireland – Parts L & E (as England and Wales)
  • Scotland – Section 6 (Energy) and 5 (sound)

Where UFH is installed in an intermediate floor where there is a separate residence below consideration must also be given to the acoustic insulation requirements of Part E. It is also recommended that insulation with a minimum resistance of 0.75m²K/W is fitted in intermediate floors where the room below is heated. This is to ensure the heat rises to the room above.

Floor insulation should be positioned directly below the UFH pipes to minimise the downward losses. In situations where the insulation is below the concrete slab, a minimum of 25mm further insulation should be laid.

In addition to the standard floor grade insulation, it is necessary to fit perimeter insulation, which is to be positioned around all internal walls. This layer acts as a separating layer between the screed and the walls and takes up the slight expansion of the screed while, helping to reduce heat loss to the walls.