Floor insulation not glued/sealed to the screed

Old butterfly, I haven't seen something like this often. They really just "slapped it together" there. As you say, no bonding of the strips, no sleeves at the doors (pipe protection), broadly and sloppily laid underfloor heating.

One can only guess what else is still wrong there :(

If liquid screed is used, the staple plates must be glued to each other and to the edge insulation strip. This is possible with appropriate adhesive tapes. So yes, poor workmanship was done here if it really did not happen. But the silverfish etc. are not necessarily due to this.

Coincidentally, the carrier for the underfloor heating, i.e. what you showed unglued, is self-adhesive. Because if you overlap the edges of the carrier and peel off the adhesive strip, the parts stick together. We installed the [Dichbahn] along with the insulation and carrier ourselves, so we know this.

If flowing screed is used, the tacker plates must be glued together and to the edge insulation strip. This is possible with appropriate adhesive tapes. So yes, poor workmanship was done here if it really did not happen. But silverfish etc. are not necessarily due to that.

And with normal earth-moist loose screed?

In this case, you can just leave it.

Yes, flowable screed was used. There are at least several areas where definitely no masking was done or it overlapped. I have to look for more photos again. To what extent can I still complain about this? How can I check if there is mold under the screed?