Insulated and plastered foundation wall, plaster is coming off

[Kurtivan]

In the summer of 2019, I attached insulation with a rendering mesh on the outside of the foundation of our house and then plastered with mortar C. After both last winter and this winter, parts of the plaster have come off. Naturally, I repaired it after last winter, and it is not exactly in the same places that it is peeling off. What did I do wrong? The plaster is unpainted.

 

[Åsa Lund]

What is the mortar in the base for your new plaster?

 

[Kurtivan]

What is the base material for your new plaster?

It is a cast foundation, then insulation with a plaster mesh on the outside, followed by plastering with c-bruk.

 

[neo11]

I think some pictures would be needed to understand better. At ground level, you should use a mortar, but above, use c mortar as you have used.