Exterior plaster crumbles and begins to form holes

Moisture and setting cracks are the causes that cause an external plaster to crumble. Most of the damage is already indicated by stains, cracks and no longer drying surfaces. If the plaster crumbles, either a processing defect is the cause or a tree lack in the masonry. The cause determines the countermeasures.

Error in processing

Plaster binds like any other mortar by the evaporation of the contained water. He developed his indispensable properties such as diffusion, weather resistance and tensile strength only well "hung". If cracks appear on the wall in the exterior render, it breaks loose from the wall and begins to crumble, this may be due to a processing error. Typical examples are:

  • Unclean mixing ratio
  • Wrong and unsuitable fillers and additives
  • Too slow or too fast application
  • Too little or too much strength of the exterior plaster
  • Too cold or too warm outside temperatures during processing and drying

Note environmental conditions

Fresh plaster needs as stable and less extreme external conditions as possible to bind perfectly. High temperatures, for example due to strong sunlight, cause the contained water to evaporate too quickly. The result is too low a hydraulic holding effect that forms.

The same happens at high humidity and sultriness or even irrigation of the exterior plaster, before it is dried through for the first time. To avoid these burdens and sources of error, the following decisions are recommended:

  • Clean up to weather conditions to avoid extreme conditions
  • If possible, organize shading and rain protection (ventilation active)
  • Do not expose fresh exterior plaster to frost
  • If possible, plaster in early summer or early autumn
  • Do not plaster in winter or in midsummer

The later crumbling can be counteracted in addition to the proper processing by a reinforcement in the form of a Gewebefachtelung. Partial crumbling can then be replaced by moisture in the masonry by large-scale lifting the exterior plaster.

Tips & Tricks

If you can assume that the external plaster will work properly, you will have to reckon with even more serious causes if it breaks. Check if your plaster draws moisture. In this case, the possible possible self-drying manifests itself in the tendency to crumble.

Product Image: Rizhka Nazar / Shutterstock

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