Installation of radiant floor heating/cooling

Installation of radiant floor heating/cooling

Radiant floor heating/cooling consists of a low-temperature system based on the introduction of heat or cold in the interior thereof, allowing the radiation to heat the room.

There are two types of radiant floor heating/cooling systems in the market


  • Water-based radiant heating/cooling:

Water pipes are distributed over the framework (see image), installing thermal insulation to prevent the heat from dissipating towards the lower floor.

A layer of cement mortar or anhydrite and sand approximately 4 cm thick is applied and subsequently covered by flooring.

Water circulates at a maximum temperature of 45ºC and the temperature of the flooring surface is 18-22ºC.

The total height of the finished flooring is close to 10 cm.


  • Electric radiant floor heating wire or cable:

Resistances are distributed over the framework (see image), installing thermal insulation to prevent the heat from dissipating towards the lower floor.

A layer of cement mortar or anhydrite and sand approximately 3-4 cm thick is applied over the resistances and subsequently covered by flooring.

The total height of the finished flooring is approximately 7 cm.

It is advisable for the nature of the flooring to be less insulating against heat or cold (stone, ceramic or hydraulic tile) and not wood or carpet.

Preliminary analysis

Thermal variations produce contractions and expansions, both of the ceramic tile and of the mortar layer on which the installation is executed.

On connecting the climate control system, the mortar screed has wider expansions on the lower part than on the upper part, due to the difference in temperature between the system as a whole (water pipes or electric wires).

This produces shear stresses in the ceramic tiles that can cause detachment thereof.

Therefore, in order to execute the installation so as to guarantee optimum adherence, we must use cementitious adhesives and flexible jointing materials capable of absorbing the movements of the ceramic pieces in the construction system.

Technical considerations

Previously, we must examine the substrate, which may be either a cement floor or an anhydrite substrate.

To this end, we must take the following into account:

  • It is always advisable to measure the humidity of the substrate before applying the adhesive.


The ceramic tiles must be laid when the substrate or floor has a degree of residual humidity of less than 3% when using the adhesive.

In the case of standard anhydrite, and under normal conditions, drying time is approximately 1 day per millimeter installed.

In the case of cement-based mortars, full setting time is 28 days.

  • The flatness of the substrate must be verified and the differences therebetween must be less than 5 mm measured with a 2-meter ruler.
  • The substrate must be clean of dust and dirt, and be resistant and stable.
  • Radiant heating/cooling system must be disconnected at least 24 hours before applying the adhesive and must not be connected at least seven days after applying the joint, thereby avoiding problems due to the dehydration of the cementitious adhesive and jointing mortar.
  • A thin bed of adhesive must always be applied using a toothed trowel, using the double-adhesive technique (toothed trowel also on the back of the tile) for tile formats larger than 2,000 cm2, except GECOL Flexible fluido (consult the technical data sheet).
  • Complete packing of all the ceramic pieces is recommended, in order to avoid condensation from forming in cavities.
  • The design of the joints is obligatory, respecting:
  • 2 mm joint spacing between tiles.
  • Perimeter movement joints in corners and changes in plane, height or material.
  • Expansion joints between door and structural cavities of the building.


All expansion joints must be filled with elastic mastics such as G#color Elastic-MS.

Jointing mortar must be applied in accordance with the times marked in the Technical Data Sheet of the adhesive.

Commissioning will take place 48 hours after executing the joint.

Recommended products



Anhydrite supports

High performance

Ultra-fast setting

High deformability

Quick setting

Anhydrite supports

Joint mortars

From 0 to 20 mm quick setting

From 3 to 15 mm

Completely watertight joints

From 2 to 15 mm

Flexible mastic

Elastomeric mastic

Warnings: The data provided by this Constructive Solution were prepared based on standard onsite installation processes. However, we recommend that you consult our Technical Department in the event of any specific circumstance