Efflorescence in the cellar - what can you do?

Not infrequently, massive efflorescence occurs on basement walls. What you can do in this case, and what cause efflorescence, you will learn in this post. In addition, as you recognize wall saltpeter on the basement wall.

Efflorescence and wall saltpeter

Ordinary efflorescence on the plaster is crystallized, dissolved salt solutions that settle on the surface of the wall after the contained water has evaporated.


Wall saltpeter, however, is due to a different chemical reaction: In this case, ammonia present in the room air reacts with certain nitrates (such as calcium nitrate) and leads to crystals on the walls. This is particularly common where remnants of excrement were present in or on the masonry:

  • in former stables
  • in cellars where animals were kept
  • after channel backlog
propertiesMauersalpetersalt efflorescence
formationFormed by reaction of ammonia with calcium nitrateFormed by washing salts out of the masonry
endangeringHigher, as leaching of the wall in some cases possible (destabilization)low
Renovation requiredYesRemoval and draining is sufficient
Appearancerather cloudy, fluffy, moisture storage capacity high, yellowish-whitedifferent, mostly dry and crumbly, whitish

Removal of efflorescence

Basically you should remove efflorescence. For a mechanical removal with a brush or a spatula is sufficient. New salts only settle again when the wall is moistened again (the water contained in the salt solution has already evaporated).

Occur efflorescence in the basement but more often, you should definitely look for the cause of Durchfeuchtung. Repeated efflorescence is a signal that moisture in the cellar regularly occurs, which can damage the building fabric in the long term.

Wall drainage and desalination

In these cases, a professional draining of the damp cellar walls is required. In addition, a desalination of the walls can be carried out to prevent efflorescence in the future. There are different techniques for this:

  • Wash out the salts from the walls
  • Compressor technology (special compresses absorb the salts)
  • victims Putz

Tips & Tricks

Also remember that you may need to remove the existing salts from the plaster ("nitrate supplies"), and therefore cut off the plaster if you want to permanently prevent efflorescence. That depends on the particular cleaning materials used and their ingredients.

Video Board: Efflorescence Tips and Tricks