Table of contents:

Remove saltpetre: the best tips
Remove saltpetre: the best tips

Video: Remove saltpetre: the best tips

Отличия серверных жестких дисков от десктопных
Video: 2 Easy Methods to Revitalize OLD Potting Soil 2023, February
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Saltpetre in masonry is a structural damage, but its striking efflorescence indicates a completely different problem. We explain how you can identify, remove and protect your walls from them in the future.

Table of contents Table of contents Detect and remove saltpetre in the masonry

  • How do saltpeter efflorescences occur in walls and walls?
  • How do you recognize wall nitrate?
  • Is saltpetre in the wall harmful to health?
  • How to remove saltpetre?
  • Eliminate the cause of saltpetre

Table of contents Table of contents Detect and remove saltpetre in the masonry

  • How do saltpeter efflorescences occur in walls and walls?
  • How do you recognize wall nitrate?
  • Is saltpetre in the wall harmful to health?
  • How to remove saltpetre?
  • Eliminate the cause of saltpetre

How do saltpeter efflorescences occur in walls and walls?

Anyone who has flowers in clay pots knows this: limestone and fertilizer dissolve in the irrigation water, seep through the clay to the outside and cause a gray-white, grubby crust. It's the same with saltpetre.

Damp walls are annoying enough, but they often cause another problem: wall nitrate. It is the product of moisture and certain water-soluble compounds in the masonry and shows itself as a whitish-yellowish to brownish coating with a cotton-like consistency. Chemically speaking, this is calcium nitrate, in the formation of which nitrates and lime from the mortar are involved. If water penetrates into walls, it often has water-soluble salts from the ground in its luggage or dissolves salts such as chlorides, sulfides or nitrate from the mortar and the building structure. These get out as a saline solution through tiny capillary tubes and pores from the inside of the wall, dry and flocculate to form whitish crystals. Since there is no salt efflorescence without moisture, cellar walls are usually affected.

Saltpetre damage in the wall

Saltpetre can destabilize walls over time. During crystallization, salts increase their volume, destroy the grout or let plaster crumble away. It's like blowing up a hard balloon in the wall.

Saltpetre attracts and stores water - the wall becomes even wetter. So there is no use in removing the building damage through moisture, but not removing the saltpetre thoroughly - or vice versa, removing the saltpetre if the wall remains damp.

Permanente Feuchtigkeit zersetzen das Mauerwerk
Permanente Feuchtigkeit zersetzen das Mauerwerk

The moisture in the walls and in conjunction with the calcareous mortar in the masonry creates saltpetre.

Photo: iStock / Cunaplus_M.Faba

How do you recognize wall nitrate?

Saltpetre or mold? Whitish efflorescence on walls always creates a moment of shock. Because damp walls can of course also be a breeding ground for harmful molds. But there are visible differences.

Saltpet crystallizes after drying and, unlike mold, the small crystals can also be seen with the naked eye. If the topping is still damp, scrape some of the topping off the wall with a spatula and place it on a board. If the surface crystallizes, it is not mold. Because it remains as a fairly uniform, somewhat greasy mass.

Is saltpetre in the wall harmful to health?

In contrast to mold and its metabolites, efflorescence from saltpetre is non-toxic, but is still unhealthy. Depending on the intensity of efflorescence, the finest particles that can be inhaled as fine dust can get into the room air when touched. Even if wall nitrate occurs predominantly in the basement, you should remove it quickly and, above all, fix its causes.

How to remove saltpetre?

Before you start looking at the causes of the saltpetre, you have to remove the efflorescence. This can cause damage to the plaster, which you should then remedy.

  • Simply remove small amounts of saltpetre with a spatula. You can also use a hard nail or wire brush to remove it. Wear gloves and a dust mask for safety. You never know whether the wall is mold-free. Sweep up saltpet crumbs that have fallen on the floor or vacuum them away with an industrial vacuum cleaner.
  • For large-area efflorescence, use chemical cleaners according to the manufacturer's instructions and ventilate sufficiently against the strong smell. Sugary cola is recommended as a home remedy. The effect is often not bad, but the sticky sugar residues on the wall and on the basement floor are not so pleasant.

Eliminate the cause of saltpetre

In order to seal and basement the basement or to protect the basement walls permanently from moisture, the root cause of the moisture must be eliminated. In the best case, it is just a broken downpipe, a crack in the masonry or a leaky terrace finish, so that water runs permanently into the masonry. Most of the time, the wall itself has direct contact with the earth; due to the lack of a horizontal barrier, the moisture rises slowly due to capillary action in the wall. Vertical locks can also be retrofitted from the outside. With horizontal barriers, this is more difficult and more complex, since they should actually be installed in the form of foils when building a house. Wall areas affected or damaged by the saltpetre must always be knocked off and replaced.

Salpeter auf einer Steinmauer
Salpeter auf einer Steinmauer

Salpeter looks very similar to white mold and is therefore often confused.

Photo: iStock / by-studio

Horizontal barrier in the wall

The horizontal barriers are perfect bodyguards for every wall and shield them against rising damp. The barriers can be set up in various ways to prevent efflorescence from saltpetre.

  • You cut or saw up the wall in sections and insert sealing membranes.
  • Stainless steel sheets are rammed in from the side.
  • Probably the most common and method is the injection of sealing chemical substances, which are run into the wall via funnels in boreholes and allowed to harden.

Protect vertical walls from saltpetre

Vertical barriers shield the entire wall from the ground - so nothing works without extensive digging, because the saltpetre gives you no choice.

  • As an outer barrier layer, dimpled sheets are placed around all walls in contact with the ground.
  • You can paint the masonry with bitumen paint or combine both methods.
  • If protection from the outside is not possible, only a veil injection from the inside is possible, whereby sealant is pressed into numerous drill holes.

Renovation plaster on damp walls

Once Salpeter has taken over most of the wall, simple sealing is usually not enough to keep it dry on the inside. This is where so-called renovation plaster comes into play, which you put on the wall from the inside. It absorbs moisture from the wall and transfers it to the surface, where it evaporates. This is the same principle of operation as with silicate panels.

Warning: usual plaster clogs the pores of the wall - as if you were simply nailing pond liner to wet wood and no longer worrying about the wood. As a result, the water pressure in the wall increases and the moisture gradually rises. Renovation plaster, on the other hand, has large pores on the inside like a sponge, in which the saltpetre can crystallize without tearing the plaster.

Thomas Hess

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