Installing a ceramic floor over an existing tile floor

The installation of ceramic on traditional substrates is not always necessary (e.g.: cement mortar).

At times, certain refurbishing work requires installing ceramic over an existing substrate of similar nature.

In this manner, we achieve greater convenience and cleanliness, on not generating rubble and speed of execution, as we avoid having to remove the existing floor.

Preliminary analysis

Normally, these old interior floors are dirty (greases deposited on the surface and on the joints). They are non-porous substrates (normally varnished) and can be found in places with a certain degree of relative humidity (bathrooms, kitchens, etc.), due to which we will need an adhesive that is:

  • Deformable, with perfect adaptation between the varnished substrate and the new ceramic piece.
  • Resistant to relative humidity and condensations.

Technical considerations

The first consideration to be taken into account is the state of the substrate on which the floor will be installed:

  • We must verify the stability of the existing floor, which must be resistant, clean, dry and perfectly anchored.


We must ensure that the existing floor is well adhered.

Otherwise, remove the loose parts, fill any cavities with a specific mortar such as GECOL Sec silíceo and let dry for 12 to 24 hours.

Clean the surface to remove all traces of residue (waxes, greases, etc.) and let dry completely.

  • Open the pores by washing with GECOL Desincrustante, diluted with water in the ratio 1:3 and afterwards rinse with clean water.
  • In order to adequately wet the ceramic piece, it is advisable to execute the double-adhesive technique, which consists of applying the product using a toothed trowel, both on the substrate and on the back of the piece.


A second consideration to be taken into account is the design of the joints, making sure to:

  • Leave at least 3 mm joint spacing between tiles.
  • Execute perimeter movement joints in corners and changes in plane, height or material.
  • Execute expansion joints between door and structural cavities of the building.


All expansion joints should be filled with elastic mastics such as GECOL Elastic-MS.

Jointing mortar must be applied at least 48 hours after installing the floor.

Commissioning will take place 48 hours after executing the joint.

Recommended products


Ultra-fast setting

Joint mortars

From 0 to 20 mm quick settin

Up to 6 mm

From 3 to 15 mm

Flexible mastic



Masonry mortar



Acid cleaner

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