The definitive solution to the humidity of the walls
For about twenty years the problem of humidity in the building sector has become more pressing, exacerbated by the obligation of thermal insulation, probably because, in the majority of cases, materials that are not always adequate for the purpose have been used. To tackle this problem, we often resort to making plasters stronger, harder, more waterproof, to resist the pressure of humidity.
New techniques have been tested, but always with the same results: delaying or diverting the escape of humidity from one's own sites, often worsening the situation, so much so that every new product aimed at eliminating humidity is viewed with distrust. The reason why humidity accumulates in the masonry is due to the fact that the partial pressure (Pv factor), at any point inside the wall is lower than the ambient partial pressure, which involves the diffusion of the humidity in the capillary way.
Masonry: the smaller the capillaries, the more it rises.
To combat humidity, research must therefore be directed towards two objectives:
- balance of the thermohygrometricity of the wall;
- trend reversal of the Pv factor, in the material with which to cover the masonry.
Up to now, in order to combat the phenomenon, attempts have been made to resist the thrust of the water vapor pressure, creating barriers with strongly anchoring plasters, not taking into account the fact that the vapor cannot be trapped, but must be favored in its escape. In fact, if we take a damp wall for example, removing the damaged plaster left uncovered by plaster, it dries up, because the steam, not finding resistance and facilitated by a favorable climatic situation, disperses into the air.
This concerns the surface of the wall, but the drying does not take place inside the wall, that is, in the thickness. In fact, the humidity would continue to evaporate if the damp surface, stoned, remained constantly exposed to the air, with temperatures that were not too low. It can therefore be deduced that the dispersion or accumulation of humidity also depends in part on the climatic factor.
After all, condensation is a climatic consequence: the passage from the gaseous to the liquid state occurs due to temperature differences, in fact the intervention of chemical or physical cutting in the walls forces the operator, before applying the plaster on the treated parts, to wait about six months, to allow the residual humidity to be dried by the air. Despite this, a certain percentage of humidity always remains trapped under the finishing plasters.
Attempts to solve the problem of rising humidity have all been thwarted so far, because no one has found a way to interrupt the rise of humidity by capillarity at the root in a timely manner. Today, a new system puts an end to the destructive action of salts and the continuous degradation of the masonry caused by rising humidity from dispersed water.
Let us now examine the new dehumidification process by means of the depressurizing plaster; however, for a deeper understanding of the subject, it is necessary to compare the mass of humidity incorporated in the masonry to the environmental condensation effect: in an environment with of temperature, between this and the internal surfaces of the building elements, in climatic conditions characterized by an external temperature lower than the internal one, the water vapor has a higher partial pressure than the external one; this fact determines a tendency of the vapor itself to move from the inside towards the outside.
The steam flow in its movement tends to cross the separating constructive element, if the surfaces with which it comes into contact have a colder temperature, to such an extent that the vapor contained in the air is higher than the saturation limit value; the excess steam condenses on the surfaces of materials or finishes with characteristics of reduced permeability to the passage of steam: (glass, metal finish surfaces, etc.) this is humidity deriving from condensation.
In walls wet by rising damp from dispersed water, the situation changes: in this case we compare the mass of humidity incorporated in the masonry to the excess water vapor in the air, so the mass of the damp wall becomes like the interior of an environment, and the face of the wall becomes like the outside of the environment.
By covering the face of the wall with a depressurizing thermal body, the conditions are reversed: the inside of the wall is cold because it is humid, its exterior is hot because it is coated with a depressurizing thermal material: as a consequence of the depressurization exerted by the particular thermal coating, the pressures are reversed: the external one of the thermally coated wall becomes lower, the internal one of the humid mass becomes higher, so that the flow of water vapor moves towards the external face crossing it without condensing, because the surface with which it comes into contact has a lower temperature. furthermore, the steam is inspired by the depressurizing thermal mass applied to the face of the wall.
Without the occurrence of the above conditions, the humidity could not move from the inside of the wall towards the surface, since the partial pressure of the water vapor would actually be lower than that of the thermal plaster that covers the face of the wall; it would happen that the higher temperature of the thermal material would tend to move towards the colder surface (the damp wall) and therefore a separation face would result, becoming an area favorable to condensation. This does not happen by applying thermo-pressurizing plaster, because with it the aforementioned pressures are reversed for the following reasons:
- the faces of the two materials (that of the plaster and that of the wall) form a single body, and having the characteristic of being highly permeable to the passage of steam, condensation does not occur;
- the plaster structure, being alveolar, behaves like a siphon with a depressurizing effect which decreases the partial pressure in the plaster itself.
