Waterproofing of foundations and subterranean rooms

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 is to prepare the surface. 

For this purpose:

  1. It is necessary to wait until the buried walls are stabilised.
  2. The surface must be properly cleaned and free of surface laitance and residues. Carry out an acid cleaning with GECOL Desincrustante and subsequent rinsing with water.
  3. Next, fill the voids and cracks in the concrete surface with a repair mortar from the GECOL Reparatec range.
  4. Carry out correct treatment of singular points (angles, corners, fissures, etc.).


Once the surface is conditioned, the waterproofing chosen from the GECOL Imper range will be applied according to the needs of the type of surface and required thickness of application.

Recommended products

Concrete repairers



Structural- fast setting



Fast setting

Thin layer from 2 to 5 mm

Thick layer 10 mm


Fast setting


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