How to repair an exterior wall affected by rising damp?

External skirting boards affected by rising damp are one of the most common problems in our homes and a pathology that must be repaired to prevent the problem from worsening and affecting the healthiness of our buildings.

Dampness, although it appears on the surface and is perceived as simple stains or efflorescence that do not seem to be a problem for the structure of the building, can also be the reason for health and hygiene problems in the interior of dwellings and the deterioration of construction elements. It is therefore advisable to combat them sooner rather than later.

Damp due to rising damp is one of the main pathologies in construction today. They can cause rapid deterioration of dwellings and an unpleasant aesthetic effect. They come from the ground and appear mainly in constructions where the walls have not been properly waterproofed, whether they are old or modern buildings, responding to a physical process in which water from the ground comes into contact with the construction and diffuses through it, rising through the pores of the materials. The Technical Building Code takes this into account with a view to eradicating this pathology in new buildings through the use of waterproofing membranes.

How are they fought?

On existing walls, the best way to combat this type of damp in the external skirtings is to apply macroporous mortar on the repaired walls, which facilitates the evaporation of the damp and prevents deterioration and the appearance of stains on the façade.

For this purpose, waterproof, breathable, adherent and highly durable solutions must be used, such as Propam Cal Sec, a mortar that ‘evaporates’ dampness and prevents the formation of saline deposits that cause stains. It is also a mortar that is impermeable to rainwater, which makes it perfectly suitable for outdoor use.

The repair can be carried out in a few simple steps:

The surface must first be cleaned by removing the plaster and degraded parts at least 50 cm above the damp mark, as well as removing the remains of damp-sensitive materials until a healthy, stable and resistant substrate is achieved. Although this product is already effective from 1 cm, it is recommended to apply the mortar in thicknesses of 2 to 4 cm (more than 2 cm in two coats) over the entire cleaned surface and at least 50 cm above the damp mark as mentioned above, as well as leaving a separation of 1 cm between the mortar and the pavement to prevent it from coming into contact with any water that may accumulate on its surface.