Will this hold for tiling on

[AndersMalmgren]

Chiseling a bit to recess tap water in the wall. I have outsourced the plastering to a craftsman. Now I suspect that he used too little water in the mix (Gypsum plaster of the brand Rotband). Large pieces of plaster are coming off when I chiseled even though I took it easy and pre-cut grooves with the angle grinder.

Now I am worried that tiles will come off the walls if I tile on this, what do you think?

 

[sponken]

Unfortunately, I wouldn't take the chance that it will stay in place. It becomes more expensive to redo it once the tile is already there...

 

[AndersMalmgren]

Thank you for the response, the hantverkare will come and take a look at it today and give their opinion.

Anyone else here have input?

 

[anders07]

Did he water the substrate or use a primer?
Gypsum plaster can behave like that if it dries out too quickly and typically if the substrate absorbs the moisture from the gypsum plaster too quickly.

 

[AndersMalmgren]

Either too little water in the mortar or didn't water the surface. He seems to have done it in two rounds because there is a layer left under the first one.