The walls are constantly damp with water, capillary lifted from the substrate, can be drained using special installations. There are several drying methods, of which are noteworthy:
a) osuszanie za pomocą bariery przeciw kapilarnej utworzonej z drenów zwykłych lub wentylowanych,
b) osuszanie elektroosmotyczne (electrodrainage).
Scheme of drying walls using ventilated drains 1 - damp ground, 2 - damp wall, 3 — dren, 4- net, 5 - part of the wall drained
The anti-capillary barrier method consists in embedding in the wall from the outside, in a fixed order and position, drains made of a special porous mass. Drains extend to the appropriate depth into the wall and form an insulating strip. Dehumidification is achieved by the flow of dry air into the wall through the drains and absorption of moisture by their porous walls. This drying method is not always effective, and sometimes even difficult to implement, especially when static considerations are involved. There is also a downside to this method, that the part of the wall below the barrier is affected by the damaging effects of moisture.
Drying the walls with drains was used in the church of St. Magdalena in Wrocław.
Scheme of drying the wall using electrodrainage 1 — mur, 2- positive electrodes, 3 - negative electrodes, 4- DC source, 5 - dehumidification field, 6 - slot for water drainage
Electroosmotic dehumidification is the use of electroosmotic forces to transfer capillary moisture towards the base of foundations. For this purpose, a source of electricity is used. The installation consists of properly placed electrodes in the wall. Negative electrodes are placed at the base of the foundations, and positive above - in the wall. By passing a direct current of appropriate voltage, the water is directed to the base and discharged outside. In addition to the aforementioned method of drying walls, other methods are also used, using electricity sources, np. using the potential difference between the ground at the foundation level and the wall, or using a combination of electroosmosis and chemical blocking. Electroosmotic methods are quite popular in Poland. The electroosmotic drying process continues, depending on/existing conditions, do 2 months. As experience shows; from Krakow, the described method is suitable, especially when, apart from drying, there is also a need to remove dissolved salts from the wall.