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The presence of saltpeter in a home indicates a serious problem of humidity. This is why it is necessary to intervene quickly to stop its proliferation but also to avoid its reappearance.

Saltpetre testifies to the humidity of the walls

Saltpeter still appears on the lower part of the damp walls. You see it as whitish powdery blooms.
Saltpetre is the consequence of capillary rise and ventilation problem:
Going back to the foundations and walls, the water causes the nitrates present in the soil. It also dissolves the potassium carbonate present in building materials. Under the action of bacteria it degrades and all forms potassium nitrate (NKO3). The latter migrates to the wall of the wall to capture the humidity of the air. In the presence of oxygen, it crystallizes.
This is how little by little the saltpetre settles in and on the walls.
This chemical reaction is only possible in the presence of moisture. Therefore, it is imperative to treat the cause of moisture before applying a anti-saltpeter treatment.

How to treat capillary rise and improve ventilation

To properly treat hair rise, you need to know their specific causes. Do not overlook a diagnosis made by a professional or better by an independent expert.

To stop the capillary rise, different solutions are possible:

  • The installation of a drainage at the level of the foundations and possibly the ground.
  • The establishment of atmospheric siphons. Drains are placed horizontally in the wall to dry it.
  • The realization of a capillary break: A resin is injected into the wall. It forms a watertight barrier by blocking the pores through which the water rises.
  • Injection into the masonry of water-repellent products.
  • The establishment of electromagnetic processes: electrophoresis, passive and / or active electro-osmosis.

To improve indoor ventilation, install:

  • A VMC (Mechanical Controlled Ventilation) single or double flow.
  • A VMR (Distributed Mechanical Ventilation). It is no longer allowed during a construction but it remains ideal during renovation.
  • A VMI (Insufficient Mechanical Ventilation). The air is filtered and preheated.

The use of a dehumidifier is strongly recommended.

Anti-saltpetre treatments

Before starting the treatment, it is necessary to start by cleaning.

  • Clean the traces of saltpeter on the walls:
    Contaminated plasters, plasters or paints must be removed.
    Then clean the wall to remove any traces of efflorescence or saltpeter patches. Brush the wall with a stiff brush. Wash in hot water with detergent, Marseille soap or Saint-Marc laundry. Rinse with clear water.
  • Apply the saltpeter treatment:
    In the trade you will find different anti-saltpeter products.
    These products are waterproof, that is, they will protect the wall from moisture by blocking the pores to prevent water from seeping through.
    They also include a bactericide to eliminate bacteria responsible for the appearance of saltpetre.
    Some are consolidating. They include a hardener that solidifies the support. The anti-saltpeter treatment is carried out indoors and / or outdoors.

After complete drying, you can paint, wallpaper or tile your wall at your convenience.

Good to know: Exterior facades may have efflorescence similar to that of saltpetre. These are in fact reactions between the soluble salts contained in the mortar and the rainwater. In this case, you will need to use an anti-efflorescence treatment.


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