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Salts caused by rising damp

Salts caused by rising damp

Having problems with salts caused by rising damp?

Rising damp is the term used to describe moisture, which gradually works its way up your walls, causing damp patches and other damage to your home. Like other problems caused by moisture, rising damp can have all kinds of effects. But if you want to put a stop to this troublemaker, you can easily arrange for a specialist company to inject your walls with Rewah products. This will prevent damp from reappearing, but can also cause moisture to collect in the wall above the injection site, which needs to evaporate.

Rising damp… packed with salts

When moisture that is still present in a wall dries out, this doesn’t in itself really cause any problems. However, over the years, this moisture can absorb salts from the ground, which spread through the wall. It is precisely these salts that cause problems. In fact, when the water evaporates, the salt dries and crystallises. As a result, efflorescence or white patches can appear on the wall. People often talk about saltpetre, but this is not quite the right term. Saltpetre is actually a specific salt and classed as a nitrate, whereas white efflorescence is mostly caused by sulphates.

Different types of salts

From nitrates to sulphates and other salts, every type of salt is different! Different types of salt can be found in walls because of rising damp. It is possible to distinguish between three main types of salts:

- Sulphates

These salts cause white efflorescence. The white patches appear when the salt crystallises. But, at the same time, the volume of salt also increases. This phenomenon can cause coatings or paint to flake, if they have been applied too quickly. For this reason, it is important to allow sufficient time before applying coatings to injected walls. You can also protect new coatings from crystallised salts, by applying a Rewah Membrasec or Membrascreen salt membrane to the wall.

- Nitrates

Nitrates are also known as “hygroscopic” salts, which means that they absorb any damp that is found in the air. When these salts are present in a wall, it may remain damp or patches may appear, even if the rising damp injection was perfectly executed. These types of salts are especially common in agricultural areas, on farms, smallholdings, stables or wherever recovered bricks are used. In such cases, it is important to cover any unattractive marks and prevent the damp air from coming into contact with the salts. In order to achieve this, salt membranes (Membrasec or Membrascreen from Rewah) can be applied to walls, before a normal coating is added.

- Chlorides

These salts mainly occur in areas where salt is stored, in walls that come into contact with de-icing salts and in coastal areas (in this case, it is known as “sea salt”). They are hygroscopic/efflorescent and can also cause bricks to become powdery. Fortunately, it is also possible to block out these salts, by using watertight membranes, such as Membrasec or Membrascreen.

Create a buffer to block out salts

You can also use salt-proof coatings to prevent the salts present in your walls from causing stains or other unattractive marks to appear. The pores found in these coatings act as a buffer, in which the salts will be able to crystallise without causing any damage. Of course, none of these coatings can create a permanent “buffer”. In fact, as soon as the pores are full, the coating can suffer further damage. For this reason, it is recommended that you check whether the rising damp has been halted. If this is not the case, salts will continue to accumulate and the coating will soon become saturated… It is also vital that this type of coating is left “open”. It should not therefore be covered with wallpaper or steam-proof paint.

Inject walls to prevent dampness. What should I do next?

If you have had a product injected into your walls, in order to prevent rising damp, any salts that are still present in the walls may still cause further problems. The best option is to apply salt membranes to the wall (such as Membrasec or Membrascreen from Rewah). However, these products can only be applied to one side of the wall, which needs to dry out on the other side.

Problems with rising damp? Rewah to the rescue!

Is your house affected by rising damp? Or have you had a product injected into your walls, but stains remain visible? If so, you can always call on Rewah. We offer a wide range of solutions designed to prevent dampness – from ready-to-use systems to quick-setting cement and injectable resins. We are also well established in the field of restoration and concrete construction. It is not for nothing that the Rewah name stands for professionalism, quality and service!

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