The construction company is building a basement smaller than in the factory plan

No answer is also an answer.

How should answers to these questions help with my problem? I really can't see it. That's why I ignore them.

How should answers to these questions help with my problem? I simply can’t see it. That’s why I ignore them.

You also consistently ignore good and well-intentioned advice. You suspect several problems with your basement but have not yet sought an expert opinion on this. What is the intention of your questions?

You consistently ignore well-meaning and serious advice. You suspect several defects in your basement but have not yet obtained an expert opinion on this. What is the intention behind your questions?

An expert I commissioned has identified and documented the insufficient concrete cover. Now the construction company should make corrections. In my opinion, the incorrect measurements for a length up to 6.66 m can also be determined without an expert. I have complained about the incorrect measurements to the construction company. As far as I know, the burden of proof for correct execution lies with the construction company. The construction company should commission an expert and prove the correct measurements. Or am I mistaken?

An expert I commissioned has determined and documented the insufficient concrete cover. Now the construction company should carry out remedial work.
In my opinion, the incorrect measurements for a length of up to 6.66 m can also be determined without an expert.
I have complained about the incorrect measurements to the construction company.
As far as I know, the burden of proof for correct execution lies with the construction company. The construction company should commission an expert and prove the correct measurements. Or am I mistaken?

Finally, some answers to questions that were raised in your other thread. And this "expert" you commissioned was also the one who confirmed to you in writing that a black tank is equivalent to a white tank with a bit of remedial work? What does this "expert" say about the durability of his proposed repairs compared to the white tank owed under the contract? - if it is actually agreed in your contract.

My expert has made comprehensive statements about the previous execution, quality in the current state, remedial measures, and expected quality. Based on this, a risk of damage occurrence, the expected extent of damage, loss of value, etc. A real expert, in short.

Let’s assume you are holding the tape measure correctly. I cannot imagine that the construction company will commission an expert because of the dimensional deviation. Okay, you have, let’s say, complained about the deviations by email, demanded rectification of defects, and are now waiting for feedback from the shell construction company. What do you think will happen next? Either you will get an explanation of why, how, technical excuses, etc., or a "sorry" — after all, it’s a shell construction. What is your goal? What do you expect as a result of the defects you (have) identified? Are they so serious that demolition (for you) is an option, or is there a chance to get everything squared away according to the ARdT? Have you verbally addressed the contractor about the insufficient concrete cover and the dimensional deviation and how did he respond?

Finally some answers to questions that were asked in your other thread. And this so-called "expert" you commissioned was also the one who confirmed to you in writing that a black tank can be equated with a white tank by doing a bit of rework? What does this "expert" say about the durability of his repair proposals compared to the white tank owed under the contract? – if it is actually agreed upon in your contract.

My expert measured the concrete cover. I specifically and solely commissioned him for this when I noticed the defects after the formwork of the basement walls was removed. I did not commission a repair plan.
The letter stating "a black tank can be equated with a white tank" was submitted by the construction company as a response. It comes from some in-house "structural engineer" of the construction company (he did not perform any calculations on my construction site).
However, construction is carried out according to the architect’s plan (shop drawing) and reinforcement plan/static calculations (from "my" structural engineer) that I provided.

Let’s assume using a tape measure. I simply cannot imagine the construction company commissioning an expert due to the dimensional deviation. Well, you have, let’s say, complained about the deviations by email, requested rectification of defects, and are now waiting for feedback from the shell builder. What do you think will happen next? Either you will get an explanation of why, how, etc., technically twisted, or a "sorry, it’s just a shell". What is your goal? What do you expect based on the defects you have identified? Are they so severe that a demolition is an option for you, or is there still a possibility to get everything green according to the ARdT?

I expect the assumption of consequential costs (e.g., adjusting the execution plans) and a price reduction. I am interested in how much money is involved (court rulings or similar).

Have you so far addressed the contractor orally about the insufficient concrete cover and the dimensional deviation, and how did he respond?

In the oral discussions, he denied all errors.
Only after the evidence from the expert (concrete cover) did he react and admit only those errors described by the expert.
He still denies the dimensional deviations.

My expert measured the concrete cover. I hired him specifically and solely for this purpose when I noticed the defects after the formwork was removed from the basement walls.

Please invest a bit more money and hire your expert for more comprehensive advice and inspection of the rest of the construction site. He will be able to tell you exactly what is reasonable, what can be resolved perfectly technically, what you simply have to accept, or when demolition and rebuilding is justified.

In the end, you may still have to weigh whether you prefer to finish building normally or endure a prolonged legal dispute with a construction halt.