Basement without additional flooring / cleaning floor slab

A decoupling mat cannot conceal the permissible unevenness of a floor slab according to DIN 18202 Table 3 Row 2, nor the "usual roughness" after its production. Therefore, the flatness and the post-treatment measure (e.g. mechanical grinding) must already be specified in the tender of the floor slab. If this was not or is not the case, the concrete surface must be assessed in detail. However, this is only possible if a mechanical surface treatment (shot blasting for large areas, brushing or grinding for smaller areas) was carried out beforehand. In principle, tiles or natural stones can be laid in a medium bed process on a correspondingly load-bearing and sufficiently even concrete surface. But even then there are some things to consider, which is why a layperson should not undertake these tasks without professional assistance (adequate pre-wetting, for example). Regards: KlaRa

Thank you very much for the many comments and suggestions! I spoke last week with our shell builder and our site manager. Both still find our plan independently unproblematic for a purely utility or storage basement. By the way, the basement will be insulated (at the side walls) and the ceiling as well. To even out unevenness, 5mm leveling compound is planned, followed by a special concrete coating. The basement stairs will also be left in their raw state. Only on the top step do we plan to have parquet like in the entire ground floor. Our primary concern is that the floor does not sand away and that one does not always come out of the basement with dirty feet. In my opinion, it is sufficient if the basement can be swept. Certainly, everyone has different requirements. The possibilities were assured to me, and apparently, some from the forum can also confirm this. In the worst case, I will have to tile it again in a few years.

The basement stairs will also be left in the raw state. Only on the top step do we plan parquet like in the entire ground floor.

Then be extremely careful that no one miscalculates the step heights.

What, now? Is your basement *inside* insulated, since walls or ceiling are mentioned? For old buildings, OK, you have to do it, but in new buildings this is... silly.

Is there still a plan on how you want to deal with moisture in the basement area, but especially how this moisture should then be kept away from your living area?

How, now? Is your basement insulated *inside*, since walls or ceiling are mentioned? For old buildings, OK, you have to do it, but in new buildings that is... stupid.

Is there still a plan on how you want to deal with moisture in the basement area, but above all how this moisture will be kept away from your living area?

Why insulated inside? No, the basement walls are insulated from the outside and the ceiling to the ground floor is also insulated. Only the floor/floor slab is not. I was told that, also because of the controlled residential ventilation, there will be no problems with moisture.