In the example we can see how the smaller diameter of the capillaries increases the phenomenon of rising humidity.
The capillary coefficient can vary from 1% of concrete to 7% of brick, up to 40% of gypsum and 70% on soft limestone
The proximity of the water table, the passage of underground water courses,
the presence of sources, the rupture of canalizations, absorbing soils and above all
acid rains (which form sulphates and nitrates that expand up to 14 times the
own volume), create enormous pressures that cause the disintegration of the plasters.
In the case of non-transpiring waterproof finishes, the crystals form invisibly
within the wall (sub-flowers) and visibly on the surface (the so-called saltpeter).
All these causes mean that in the absence of an isolated foundation there is a risk of
capillary ascent. It is the most harmful form of humidity, as it contributes to rendering
insalubrious housing and threatens its solidity, undermining its foundations.
The water rises in the wall due to the presence of capillaries.
By physical principle, the consequent adhesion force between water and capillary walls
prevails over tension surface water, and the equilibrium is higher than the hydrostatic level.
The well-known meniscus is therefore found inside the capillary.
In case of restoration of old buildings, priority must be given to the capillary ascent, without whose treatment a real improvement of the comfort of the dwelling can not be realized.
The biggest and common mistake that is made in the presence of rising damp is to consider the phenomenon as a simple passage of only water from the ground through the wall, then resolved with a simple remake of the plaster (possibly aerated and hydrophobed), not considering so that the rising water is a solution of salts, more or less concentrated, that are formed due to acid rains.
This type of intervention does not eliminate the problem definitively because, with the passage of time, the salts contained in the rising water occlude the pores by crystallization, thus making the plaster impermeable and raising the invasion of moisture.
Another common mistake is that of intervening by aerating the flooring or recreating the external waterproofing (underground walls such as taverns, cellars and boxes): the wall in contact with the ground actually continues to absorb water independently.
The chemical barrier, unlike macro or microporous plasters, definitively blocks the capillary rising at the base of the foundation, is unalterable over time because the mineral nature is similar to that of the walls, does not pollute the environment and above all is harmless to humans .
The water contained in the ground below the chemical barrier remains static (still) and does not cause any other damage in the other walls as the wall absorbs it spontaneously by capillarity (sponge effect).
The chemical barrier creates at the base of the wall an impermeable layer (diaphragm) without creating problems of static structure, as happens instead with mechanical cut.
The cost of the chemical barrier is amortized over time as it eliminates costly and repeated interventions on the facades, for an almost indefinite period, provided that no exceptional atmospheric changes occur, such as the formation of unknown acid rains.
An important factor, in the event of a capillary rise, is the decrease
of thermal insulation: a wet wall loses up to 80% of its resistance
to passage heat.
In case of renovation of a building, the elimination of rising humidity
it is the first intervention to be performed, especially in anticipation of a project of
thermal insulation; otherwise the humidity would rise and aggravate
much the state of the inner walls, canceling the effectiveness.
OPERATIONS TO AVOID IN PRESENCE OF HUMIDITY OF RISING:
Cement plaster: its high strength and compactness eliminates the surfacing of salts on the surface, but over time these accumulate in the interface, causing the so-called "folder" phenomenon due to the crystallization of salts. The rising damp again immediately raises the level of water invasion.
Waterproof coatings, waterproof finishes: avoid the existing plaster treatment with imaginary resin mortars or with masking or gluing to avoid the problems described above.
Micro or macro porous plasters: these plasters increase the rate of evaporation of water in the form of water vapor, but the salts are filtered and retained in the same plasters or, in the case of water-repellent properties, in the structure. Over time the accumulation creates the occlusion of the pores of the plasters or of the structure in the interface, making them in fact impermeable and giving rise to a new ascent.
Drains or interventions on floors: another common mistake is to intervene by arranging the flooring or by recreating the external waterproofing (underground walls such as taverns, cellars and boxes), as the wall in contact with the ground continues to absorb water independently.
Aerator insertion: aerators of any type have proved to be ineffective over time because the external climatic conditions, varying, hinder the outflow of humidity. Furthermore, the phenomenon of salts expansion remains unaltered.
DRYING TIME AFTER THE BARRIER FORMATION:
Wall drying times are greatly influenced by environmental conditions such as temperature, external humidity and ventilation.
It is believed that a wall in ideal conditions can dry on the surface for 3cm depth per month. For example, a wall with a thickness of 40 cm, stonework, with relative humidity of 40-50%, average temperature of 20 ° C and good ventilation, would take about 7 months. But this does not mean that you have to wait so long: already at a distance of 15-20 days, thanks to the treatment with Antisale Zero and the use of a lime-based breathable plaster added with Micron ds, you can proceed with the restoration of the walls finishing them with transpiring paints.
HUMIDITY FROM THE OUTSIDE
When the rain wets an exposed brick façade, in concrete, exposed stone and in cement or lime plasters, and in all cases of porous and absorbent materials, penetrates more or less deeply, causing these problems:
• Slow and progressive deterioration of the support
• Risk of cracks due to freezing-thaw periods
• Formations of whitish spots due to salts present in rainwater (acid rain)
• Persistent traces of dark patches of moisture
• Mold formations
• Neckline neckline
• Significant reduction in the insulating power of the wall: the thermal conductivity can be higher than 25 times compared to the dry surface
The treatment with external water-repellent impregnating products gives the facades of any type the characteristic not to allow water to penetrate into the pores and not to cause the alterations described above.
The duration of these treatments depends on their more or less high quality chemical composition.
The peculiar characteristics are the permeable protection against water vapor and the respect of the integrity of the treated material, without any chromatic alterations.
Our Guardian Zero product reflects all these features with a mild consolidating effect.
HUMIDITY FROM INSIDE
The attack of moisture from the inside is the least visible form. In these cases, water appears in the form of steam and can only be ascertained when it comes into contact with a cold wall. A cold wall may be due to the presence of humidity (both for ascending and from the outside), due to poor thickness and therefore due to lack of insulation, temperature difference between inside and outside, and poor ventilation of the rooms.
In practice, the so-called dew point, ie the change of state from gaseous vapor to liquid water, takes place not within the structure but on the surface (Glaser diagram).
The disadvantages caused are: formation of superficial molds, unpleasant odor, possibility of attachment to clothing and furniture as well as cause of malaise for those who live in those environments.
Our Nanargentum product based on nanometric silver is
the ideal against the proliferation of mosses, fungi and lichens.