Saltpetre in the cellar - causes and dangers

Saltpetre in the cellar is often confused with mold. However, this is a fundamentally different phenomenon. What causes saltpetre formation on the basement walls, and what risks can threaten, and how to avoid them, reveals the following guide.

Everything about salt efflorescence

  • Causes of Salpeter efflorescence
  • possible risks
  • remedying

Causes of Salpeter efflorescence

Salpeter looks like mold at first sight. In fact, however, they are efflorescent salts of nitric acid.

Salpeter is recognizable on the one hand by its crystalline consistency, which distinguishes it from mold. In addition, saltpeter is always dry, while mildew is usually slightly moist on its surface.

Saltpetre in the cellar - causes and dangers: efflorescence

Saltpetre results from a reaction of excrement or urine with oxygen and a subsequent reaction of these substances with the lime contained in the masonry. As a rule, saltpetre is therefore found in stables and in cellars that once stood on agricultural land.

Salpeter efflorescence occurs only when contaminated moisture can rise up the walls.

Possible risks

Nitrate infestation is not dangerous in itself, but a clear sign that the affected wall is heavily moistened. The constant moisture penetration can lead to the yielding of the masonry.

The odorless, harmless saltpetre is therefore only a warning signal. It should be taken seriously. Constantly moistened masonry can also tend to form mold. In addition, efflorescence of other salts from the masonry can lead to an even faster reduction in carrying capacity.


The saltpetre coating itself can be easily removed - but to remedy the moisture penetration of the wall is usually more complex.

As long as the wall is not completely drained, it will come again and again to efflorescence. After draining, a desalination of the wall can also be carried out in the case of severe infestation, which can also remove stored saltpetre from other salts in the masonry.

Such desalinations are carried out by professional refurbishment companies. They can be done in the course of draining the wall with the same.

Tips & Tricks

When drying, it is important to pay attention not only to a horizontal but also to a suitable and sufficient vertical seal. Saltpeter infestation is a sign that the moisture in any case penetrates from the outside into the wall.

Video Board: Efflorescence Tips and Tricks