Onsite shower tray construction

The latest trends in decorative projects replace bathtubs and prefabricated shower trays (ceramic, polyester, resin, etc.) with the onsite execution of these elements.

This type of construction work is essential to ensuring the impermeability of the unit of work which, while being a more versatile installation in terms of better use of space and aesthetic possibilities, there may be a greater risk of filtrations due to the discontinuity of the unions of different materials.

Preliminary analysis

As preliminary considerations to ensure the success of these projects, we must follow guidelines that will resolve possible leaks.

  1. The substrate with which we are working must be stable and its special points correctly treated (angles, corners). (For further information, consult the Constructive Solution “Execution of angles and corners for perfect waterproofing.”).

A half cane must be executed in these points, thereby allowing the water to slide uninterruptedly.

2. Once perfectly treated, clean, stable and free from fissures will be adequately waterproofed and subsequently clad with ceramic tile.

3. After cladding with the adequate ceramic material, the joints between the pieces must be correctly treated, guaranteeing the watertightness of the unit of work.

Technical considerations

Taking the type of substrate into account, it is advisable to use one waterproofing mortar or another.

  • Ceramic brick substrate: Use GECOL Imper-G.

The minimum thickness to ensure complete waterproofness in all points is 10 mm.

  • Cement or concrete mortar substrate: Use GECOL Imper-F, GECOL Imper-E orGECOL Imper-R.

Apply two cross coats of product, allowing approximately 4 hours to elapse in between. The minimum thickness to ensure waterproofness in all its points is 3 mm. It is recommended to ensure the minimum thickness of application, especially in singular points (half rods in plane changes) it is recommended the use of a fiberglass mesh resistant to alkalis GECOL Malla 70 gr.


The waterproofing mortars must be wetted 24 and 48 hours following application thereof to ensure the adequate setting and hydration of the cement.

All connections with plumbing elements must be adequately treated with watertight joints.

Both the flooring and the wall must be waterproofed up to a minimum height of 1.5 m.

Once the substrate has been treated with the adequate waterproofing mortar, the chosen ceramic cladding will be applied.

For waterproofing with GECOL Imper-E, a deformable material such as GECOL Flexible premium will always be used as an adhesive.

In fast waterproofing with GECOL Imper-R, the use of a rapid-setting adhesive GECOL Flexible rápido and a fast setting joint mortar GECOL Junta premium are recommended.

In all cases, it is advisable to apply a thin layer of flooring and execute the double-adhesive technique (application of the product using a toothed trowel, both on the substrate and on the back of the piece), for formats larger than 2,000 cm2.

A second consideration to be considered is the design of the joints, making sure to:

  • Leave at least 2 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

  • Execute intermediate movement or partition joints that constitute maximum surface areas of 50 m2 in interiors, 25 m2 in exteriors and 16 m2 with dark colors in exteriors.


Jointing mortar must be applied at least after 48 hours.

Commissioning will take place at least 48 hours after executing the joint.

Recommended products


Fast setting

Thin layer 3 mm Elastic

Thin layer from 2 to 5 mm

Thick layer 10 mm


Ultra-fast setting

High performance


Joint mortars

From 0 to 20 mm quick setting

Up to 6 mm

From 3 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 info@gecol.com