Under Floor Heating Concrete flooring

Under Floor Heating Concrete flooring

Under Floor Heating

Installation with Under Floor Heating

Concreate concrete panels can withstand temperatures upto 80ºC  so can be used with more flexibility than most floors, however the following information should be followed.

This section is especially important when installing the Concreate wood flooring panels, which must be used like a conventional engineered wood floor.

Follow the guidelines detailed in this section in conjunction with the installation guides for Concreate Flooring.


  • Avoid accelerated drying of new concrete/screeds over UFH as this may lead to poor cohesive strength of the sub-floor.
  • Check the cohesive strength of screeds before adhering.
  • Ensure that screeds, concrete, etc are 65% RH  before  installation commences.
  • Employ a suitable surface applied moisture barrier (e.g. moisture suppressant primer) where necessary.
  • If leveling is required  above a suitable primer moisture barrier, apply a purpose-made fine graded aggregate over the second coat (on one coat membranes) OR third coat (on two coat membranes) immediately after application. Allow to cure then vacuum off all loose aggregate; (This will aid adhesion between primer and levelling compound). Then use a rapid dry formulae‚ water-mix (i.e. instead of latex mix) levelling compound, as these are typically stronger and develop strength quicker.
  • Ensure that levelling compounds are  fully cured and dry  before installation commences (see manufacturers technical data-sheets).
  • Always use Concreate Flooring Adhesive.
  • Ensure full contact between the underside of the panels and adhesive.
  • Maintain suitable ambient humidity 45 to 65% RH. (Monitor with a domestic hygrometer).
  • Employ floor temperature sensors below the floor with electric under floor heating systems.

 Do not…

  • Do not allow humidity below 45% RH, or above 65% RH. (A small domestic humidification unit can be employed to avoid low humidity during the winter heating cycle if necessary.
  • Do not allow the floor surface temperature to exceed 27°C, (including under rugs and furniture).
  • Do not use thick insulating rugs. (Note: as this will lead to high floor temperatures).

Precautions prior to installation where under floor heating is to be used

Before floor laying begins, the following procedure should be followed:
The screed should be dried in accordance with BS8201:2011. Once the screed is dry to a maximum level of 65% RH for floors the under floor heating should be commissioned in accordance with the under floor heating manufacturers guidelines where available.

1) Day 1: 20°C

2) Day 2: 30°C

3) Day 3: 40°C

4) Day 4: 50°C or the maximum planned operating temperature. This should be maintained constantly for a minimum of 7 days.

b) Cooling Down. The flow temperature should be cooled to a specific temperature as follows:

1) Day 12: 40°C

2) Day 13: 30°C

3) Day 14: 20°C

4) Day 15: The under foor heating should be switched off.

At least 4 days should elapse before final moisture readings are recorded (If more than 7 days elapse between the last cooling-down day (day 14) and the start of laying, the under floor heating should be run at a minimum operating temperature of 40°C for 2 days. The under floor heating should then be switched off for at least 4 days before a further moisture check is carried out prior to laying.

Testing of UFH services

The flooring installer should ensure that all services (not only heating services) running beneath the floor have been tested fully by the services installer before laying starts.

Provision for expansion

As a guide only allow a minimum 10 mm expansion wherever the floor meets obstacles including perimeters walls, structural supports, hearths etc.

Where practical install flooring parallel to the longest walls so that the direction of greatest potential expansion (i.e. across the grain) does not coincide with the direction of greatest dimension, esp. in large floors.

The precise combined provision for expansion must be judged by the installer taking into account environmental humidity, moisture content of wood at time of installation, timber species and size of the floor.

Precautions prior to handover

Means of keeping the flooring dry and stable in the period between laying and handing over should be provided.

Start up schedule

Where under floor heating is involved, particular attention should be paid to ensure that the top surface temperature of the wood flooring should not exceed 27 °C. Some electrical under floor heating systems are not compatible with timber flooring. It is most important that electrical UFH systems must be overlaid with a fibre reinforced smoothing compound of not less than 5mm no direct contact of any electrical matting should come into contact with the wood floor itself. Please seek the advice of the UFH manufacturer’s instructions to confirm compatibility with wood flooring.

Important notes

Always check the mutual  compatibility  of moisture barriers, primers, aggregates, levelling compounds and adhesives before installation.

Disclaimer & further information

This information is not intended to be exhaustive, or a how to guide for the novice, but will serve as a guide only to the experienced installer. Further information is available in request.

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