Detect And Repair Plaster And Coating Damage

If a coating is to be applied to an older, lime-rich existing plaster, it is important to carefully check the circumstances beforehand.

It is well known that certain signs of aging appear on facades over the years.

Inevitably, weather-related influences become visible over time, such as: B. the accumulation of dirt, the change in color or the appearance of individual cracks. If one considers the possible durability of a facade coating of approx. 20 years, reactions of this kind are not surprising. After all, building facades and their coatings are exposed to constantly changing weather and environmental influences, but if there are massive cracks and flaking, additional factors are very likely to be the basis. As an example, it can be assumed that the universally applicable dispersion facade paints cannot be reconciled with lime-rich plasters. Because the so-called air lime mortar requires constant exchange with the ambient air, especially carbon dioxide, and water. The interaction and weather-related changes in the cleaning moisture have a positive effect on the durability of the mortar structure.

Although emulsion paints can be described as water vapor diffusible, applying them to lime or even lime mixed plasters will lead to plaster and coating damage within a few years. Nevertheless, facade paints, if applied several times, can have a negative impact on the natural reaction between mortar and weather. The consequences are serious loss of strength in the plaster surface and the loss of the adhesive strength of the coating. Silicate or high-quality silicone resin products are particularly suitable.

Plaster and facade paint interact with each other, that's for sure. The causes of serious defects in painted existing facades can still be "deeper". If, for example, an insufficient primer was used, this can also lead to unsightly coating and plaster damage. The primer plays an important role as an adhesion promoter between the surface and the coating.

Conclusion:

In this way, damage to facades and the associated complaints can be avoided.

Author: Roberto Bongiovanni Master painter and state-certified paint and varnish technician Head of application technology at ZERO-LACK