Quality of interior and exterior plaster

Hello construction community

I had hoped not to have to publish anything in this forum, but apparently it really cannot be avoided on any construction site...

After several conversations with the construction management, construction planning, and my painter, there are currently major disagreements regarding the quality of the interior plaster. The trade was contracted separately. A lime-cement plaster was specified.

According to construction management, the interior plaster is fine and of the agreed quality, as specified (ready for wallpaper). Unfortunately, as one never stops learning, the service description lacks an indication of a quality level, as I have now had to learn. It is supposed to be Q1, but even my painter vehemently doubts this and I can understand that when looking at the pictures from last night when we wanted to discuss tiles and walls. At first, it was about the plaster not being smooth, but dents and waves are visible. Even the joints of the brick rows are partly extremely visible and wavy.

Now, about a month after the screed has been in the house, bubbles are forming everywhere in the plaster that you can easily scrape off with a fingernail, and underneath there are large holes in the plaster. The painter took a sanding machine to see if it could be sanded or if it was extremely hard. He barely applied any pressure and a cloud of dust appeared; you can immediately sand several millimeters off the plaster under a cloud of dust, and underneath it becomes extremely coarse, rough, or whatever, but the painter now even says he does not know if putty will hold at all on the surface. A corner bead along the ceiling edge was only applied after being pointed out, although it was specified.
Can someone give me advice or try to interpret from the pictures what might have gone wrong here?

The situation with the exterior plaster is perhaps even worse (same company). All the window reveals are twisted, the finishing strips are partly interrupted multiple times and repaired with silicone. They now want to hook the window reveals again on the ground floor and replaster them, but a friend told me that this definitely destroys the exterior appearance of the plaster (textured plaster) and that you will never get a perfect 1:1 match again, so that the point where it was hooked in will always be visible.
Is that true? Upstairs they said it looks like it evens out after some time. The attached picture shows the small gable window under the roof, but it is most visible in the pictures there. Unfortunately, almost every window looks like this.

Good morning,

According to the construction management, the interior plaster is fine and of the agreed quality, as specified (ready to wallpaper). Unfortunately, one never stops learning, the specification lacks the indication of a quality level, as I have now learned. It is supposed to be Q1 ...

I would - based on visual inspection and therefore with reservations - also guess at most Q1 and kick the construction management (CM) in the rear. "If no quality level is expressly agreed in the contract, Q2 is considered agreed."

but even that my painter vehemently doubts ...

Painters always "grumble" about the quality of the existing plaster; that is my conclusion from years of work. In this case, however, he is right.

Did your contractor know what final treatment of the walls you planned? That belongs in the tender documents so that the plaster can be prepared accordingly.

Can someone give me advice or try to interpret based on the pictures what might possibly have gone wrong here?!

Interpreting does not help you and achieves nothing as it does not change the status quo. If your contractor, site manager, and you cannot reach an amicable solution, an expert for plasters must be brought in to suggest solutions. I would assume it has to be completely replastered; whether the old skim coat must be removed for this can only be answered by an expert.

An even worse picture with the exterior plaster (same company). All window reveals are twisted,

Despite looking several times, I cannot grasp what you mean. Do you possibly have better photos?

... but a friend told me that this definitely destroys the outer appearance of the plaster (textured plaster) and can never be perfectly matched again, so that the point where it was resumed will always be visible. Is that true?

Yes.

Rhenish regards

Where is the passage: "If nothing is agreed in the contract ... Q2 is considered agreed" from? Is that stated anywhere officially?

The side walls of the windows (window reveal?) are crooked. If you look at the wall from top to bottom, you see nothing at the top, it is dark there, and at the bottom edge of the window you see the white interior wall.

Where is the passage: "If nothing is agreed in the contract ... Q2 is considered agreed" from?
Is that stated officially anywhere?

"Problems in interior finishing – Sheet 24.1.11 Requirements claims for a skimmed gypsum plasterboard"

Excerpt:

Information sheet 2 describes in detail the requirements for the respective quality levels. Therefore, the contract must specify the target quality levels. If nothing is agreed, the quality level Q2 is automatically considered agreed. Consequently, the Q2 claim class is the standard skim coating.

Rhenish greetings

Comprehension question: Can the information sheet, which relates to filling of gypsum board panels, simply be applied to plastered walls (solid)? And, please correct me if I'm wrong, isn't the assessment of plastering work under grazing light inadmissible? I think I read something like that once, but I can't find where anymore. (Although the plaster surface here will certainly look terrible even under normal light)

If you look at the wall from top to bottom, you see nothing at the top,

Can you simply upload the images directly here?