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Treat the humidity of a wall

Moisture is a sneaky enemy capable of slowly degrading the masonry of a wall. Masking under a coating, whatever it is, generally has the effect of accelerating its work of undermining and compromise the holding of a lining or facade. The paths through which water infiltrates can have various origins: runoff, gutter leakage, infiltration, etc.

Symptoms and their causes of moisture

The humidification of a facade is often the result of seepage-related infiltration. The combined absence of gutters and gutters is certainly the cause here.

Moisture on a facade

There is almost always an effective remedy for stopping moisture, provided that the treatment is well adapted to the real disease; hence the importance of searching carefully fororigin of this moisture, in order to stop the spread. According to the results of this analysis, the treatment will prove more or less complex and expensive.
Inside, start by clearing the wall of its coating, especially if it is very degraded (blistered, scaly, presence of efflorescence or saltpeter). Brush and leach the surface, then appreciate the extent of the phenomenon.

The presence of moisture on or in a wall can be different in different ways:

  • whitish efflorescence, generally more widespread at the base of the wall, are the mark of saltpetre which denotes a saturation of the masonry;
  • powdery patches of gray mold that mark the areas of condensation are most often behind furniture;
  • blackish spots localized especially in the angles and at the lower part of the wall are the result of a rise of water by capillarity.

The origin of the water can be easily determined by placing on the wall a aluminum foil 50 to 60 cm longg, fixed by a self-adhesive tape on all its perimeter. Remove it after 3 to 4 days and examine on both sides to see where the moisture is coming from. It's about:

  • condensation, if the moisture covers only the face facing the room;
  • infiltration, in the masonry if the sheet is covered with a damp film on the side facing the wall;
  • a combination of both phenomena, if both sides of the leaf are moistened.

Infiltrations and upwellings

The infiltration of water into the soul of the walls is the most dangerous disorder for any building. We must first go back to the source of the infiltration, which is often enough to blind.

Downward infiltrations
The descending infiltrations come from cracks in the roof, in the walls or the frames of the openings. Treat them in two stages:

  • Locate the crack (es) and fill it with a suitable sealant;
  • after allowing the wall to dry (approximately one month), apply a hydrophobic product to the surface to be tiled.
Through infiltrations
The through infiltrations come from the rainwater absorbed by a porous and / or cracked facade. Treat the cause first, let the wall dry, then protect the siding to be coated.
Upwelling from the foundations
These upwellings are treated by creating a water repellent barrier at the heart of masonry, injecting a organometallic resin in holes practiced at an angle (every 15 cm) about ten cm from the base of the wall.

Wall treatments against infiltration

The waterproofing of a wall in the basement passes by the loosening of the foundations.

Unburden the foundations

Foundation treatment
1. Begin by removing the foundations at the base of the exterior walls. Never dig below the level of the foundations of the walls.

The waterproofing of foundations is done with a bituminous product applied by brush.

Apply a sealant

2. Apply generously a bituminous sealant on the base of the foundation walls, down to the ground level. Replace the soil after drying the product.

A sealed barrier can be obtained by injection of resin under pressure at the base of the walls.

Injection treatment

Resin injection treatment
The creation of a barrier against upwelling from the foundations is done by injection of a product in hollow plugs forced into holes drilled at the base of the wall, by means of a compressed air gun.

Treatment against condensation

In many old dwellings, the ventilation is done in a natural way, by entrances and outlets of air pierced in the walls. Extractors can speed up the ventilation process.

Natural ventilation

Natural ventilation
Effective aeration remains the first remedy against moisture condensation. It is also an often unknown prophylaxis against many small respiratory and dermatological diseases, since latent moisture is a breeding ground for pathogenic or allergenic germs and fungi.
Natural ventilation, the most basic, is achieved by a sweep of air entering through grids located at the top of the windows, then passing under the doors to be finally evacuated by an aerator or extractor.

Mechanical ventilation
The first remedy is to improve ventilation:
- by installing a VMC (controlled mechanical ventilation);
- by installing a VMI (ventilation by insufflation) if the configuration of the premises does not allow the installation of a VMC;
- by the installation of distributed ventilation (extractors) if neither of the two previous solutions is possible).

A thin layer of expanded polystyrene may be sufficient to neutralize the cold wall effect and prevent condensation.

Laying a thin insulation

Avoid the phenomenon of cold wall
Condensation can be avoided by preventing the ambient air, which is more or less charged with water vapor, from coming into contact with the cold surface of the walls. For that there are two solutions:
- thermal insulation effective, exterior or interior;
- laying a layer of insulation thin (Depron) on the surface of the interior walls.

(photos / visuals: © DIY-Prod, except special mention)

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