Waterproofing of foundations and subterranean rooms

In subterranean car parks, basements, cellars, elevator pits, etc., damp and leaks may appear that degrade the coatings and cause the appearance of efflorescences, creating unhealthy environments.

Traditional solutions such as asphalt cloths, bituminous or elastomeric paints, do not resist the counterpressure exerted by the water outside the wall.

In order to ensure the waterproofness of these types of rooms, a treatment that resists the counterpressure of the water and cannot be attacked by salts is required.

Preliminary analysis

The main peculiarity of this type of waterproofing is that the water exerts a negative pressure on the waterproofing mortar, due to which the join between the mortar and the base must be greater than the pressure exerted by the entrance of the liquid.

Another characteristic to be taken into account in these types of filtrations is that water, as it passes through the terrain, transports the salts they find dissolved.

Therefore, the use of waterproofing agents that resist the chemical attacks of these types of salts is essential.

Technical considerations

The first step to be taken into account is the preparation of the substrate.

To this end, we must:

  • Firstly, wait for the subterranean walls to be stabilized.
  • Adequately clean the substrate, ensuring that it is free from surface grout and residue. Make an acidic cleaning with GECOL Desincrustante and subsequent rinsing with water.
  • Subsequently, fill in the cavities and voids of the concrete substrate with a repair mortar of the GECOL Reparatec game.
  • Correctly treat special points (angles, corners, fissures, etc.).
  • Once the support is conditioned, the waterproofing chosen from the GECOL Imper range will be applied according to the needs of the type of support and thickness of application.

Recommended products

Concrete repairers


Structural- fluid

Structural- fast setting


Fast setting

Thin layer 3 mm Elastic

Thin layer from 2 to 5 mm

Thick layer 10 mm



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 info@gecol.com