Surface cracks in screed

Hello "Marchonisch".
"A friendly greeting at the beginning of the text, a small closing word at the end of the request, would certainly please the voluntary responders here in this forum as well, as it shows courtesy and style."
That a screed cracks in the form shown in the photos is indeed unusual. That a flow screed (and here the interesting question would be whether it is based on cement or calcium sulfate binder) cracks this way indicates more than just structural (constructive) constraints.
It is true that a screed, after crack repair (and cracks can always sporadically occur in screeds), should be considered a proper trade; however, in the case of larger cracks, the question of WHY should be asked.
In a property I inspected in Bad Neuenahr, it was undoubtedly a material defect; in a hotel in Frankfurt, which I am again inspecting today, it is a special screed construction that did not work.
You can decide for yourself whether you want to solve the problem with the screed layer, who will probably be your contact person, or whether you want to bring an expert in the trade (screed or flooring technology) on your side.
The question of WHY regarding the crack formations cannot be answered from a distance. For that, you need to know the history of the screed and, if necessary, partially open the construction.
What ultimately only means that the layperson is overwhelmed here and general advice from the internet cannot (always) be helpful.
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Regards and good luck: KlaRa

Thank you all for the quick feedback. My heating engineer says that these are not cracks and everything is fine. The architect says the same. Nevertheless, I will confront the screed layer again about this. It is cement flow screed.

My heating engineer says that these are not cracks and everything is fine. The architect says the same.

What is it supposed to be if they are not cracks?

Sorry, I just had another conversation with the [Estrich Leger].

We received an anhydrite liquid screed. The cracks are only on the surface and disappear after sanding.

We slightly removed the surface at one "crack". Afterwards, no crack was visible anymore.

Sorry for the wrong information regarding the type of screed.

I am now torn back and forth and don’t know what to believe anymore.

How do you assess this (taking into account the new facts (sorry))?

.... We received an anhydrite screed. The cracks are only on the surface and disappear after sanding.

We removed a little of the surface at one "crack". Afterwards, no crack was visible anymore.

..... I am now torn back and forth and no longer know what to believe.

How do you evaluate this (considering the new facts (sorry))

Why shouldn't you believe your screed installer? If everything is still going to be sanded (never heard of that), and then the superficial cracks (we cannot see or assess how deep they are) disappear, then everything should be fine.

Hello "Marchonisch". There are surface-near cracks. In cement screeds and concrete as well as in calcium sulfate screeds, if the latter were not installed as flowing screed (then they should not exist). A crack only deserves attention if it is a separation crack that runs completely through the screed structure. This would certainly not be removed by grinding, whereas the surface-near crack would be. So you can tell after grinding what type of crack it is: surface or separation crack. The former usually occurs due to drafts during the fresh phase, the latter only after several hours or days, when the screed’s inherent strength develops and stresses are released through weaknesses in the structure. Separation cracks must be repaired before the floor layerer intervenes. This is nothing extraordinary but must be done. The costs for this? The screed installer initially takes responsibility for this as a defect in the screed. ---------------------------------- (Höflichkeitsformel:) Regards: KlaRa