Anhydrite screed has a water damage - what to do?

Anhydrite screed is very sensitive to moisture. If water reaches the screed, the problem is usually serious. What you can do when a water damage has occurred on the screed, and what consequences can have a moisture, learn in our article.

Properties of anhydrite screed

Anhydrite screed is also called calcium sulphate screed - this already shows where the main problem lies. Calcium sulfate is simply gypsum, and gypsum tends to swell on contact with water.

By permanently swelling, without the possibility to dry, the anhydrite screed is irreparably damaged. A decay of the screed occurs after a moistening for about 2 - 4 weeks. After that, the screed is usually not to be rehabilitated.

Problems with heating screed

In the case of heated screeds, there is generally still an insulating layer below the screed. If this insulating layer is also moistened, the damage is usually even greater.

The insulation material falls within a few days, at the latest after a few weeks, together. It has thereafter no more insulating in a wetted state.

In addition, mold can form in the damp insulation material after a short time, which is difficult to remove.

Screed drying and insulation drying

After a water damage must be started immediately with a professional drying. In addition, the screed may under no circumstances be stressed when it is in a moist condition.

If an insulation layer below the screed is also affected, the main focus is on insulating the insulation. Holes are usually drilled in the screed through which warm air is blown. In this way, the insulation layer is completely dry. Any existing mold will be deprived of the basis (mold only thrives in damp, in drought it dies).

The measures are thus:

  • if necessary, determining the cause of the ingress of water, stopping the cause
  • Dämmschichttrocknung
  • screed drying
  • if necessary, renewal or improvement of seals (edge ​​insulation strips, etc.)

If the screed is thoroughly dried in a relatively short time, there is no further damage. The screed becomes firm again and fully loadable. However, drying must be started immediately.

Tips & Tricks

In the new construction phase, a dampening of the screed can often even be positive in the long term: due to the necessary drying of the screed, the screed becomes very effective and completely dry - which is otherwise difficult to achieve with the usual moisture input in new buildings.

Unrecognized damage to the screed

If - for example in a bathroom - moisture reaches the screed undetected, this can be a big problem. If the moisture is trapped and can no longer escape, the screed is destroyed over a long period of time.

In problematic areas, the screed should therefore be as well as possible to protect with waterproofing, in wet rooms due to the high risk as possible no anhydrite screed should be used.

Video Board: How to reduce the drying time of screeds