Shower sealing of wall & floor in one work step? DIN 18534

Hello,
here is the question directly:
Does the sealing of wall and floor in the bathroom – especially in the shower – have to be done in one continuous operation?

Our situation:
The house handover is in 2 weeks and currently all the tiles on the wall are installed, only the floor is not yet.
Our expert has recorded this as a defect and instructed to remove all tiles, carry out the sealing of wall and floor in one operation (+ documentation) and then put the tiles back on.
The developer now only wants to remove the bottom tile and seal from there.

Summary:
Can we refuse the handover if it is not done according to the expert’s recommendation?
What does the standard say? Would we have to accept the developer’s "temporary solution"?

Thank you very much for your advice.
Best regards
Simon

I am not familiar with the DIN standards, but for purely logical reasons, you can’t properly apply liquid foil anymore. How did he imagine it? Tape off the bottom tile and then brush the gap between the tile and the floor sufficiently thick and dense with liquid foil using a thin brush?

I'll join in here. This is about a developer, but to which trade does the sealing of the shower area belong? To the plumbing trade or to the tiler trade? It would be interesting to know, especially when it comes to individual contracts and/or own work. So who usually takes care of the sealing? Or is it all a matter of negotiation?

I'll join in here.
This is about a developer, but to which trade does the sealing of the shower area belong? To the plumbing trade or to the tiling trade?
It would be interesting to know, especially when it comes to individual contracts and/or own work.

So who usually takes care of the sealing? Or is it all a matter of negotiation?

The developer builds the house and contracts out the interior work to different trades. I don't know exactly who is responsible for that – but for us, only the developer matters, from whom we take over the house in the end. That's why it is important for us to know if we can insist that the sealing is done completely new and properly? (Whoever is responsible for that and possibly covers the costs, that is something the developer has to deal with.)

Obviously, this is not important to you. I did not ask this thematically related question to you either, but hope that someone else who is knowledgeable and can help you further might also answer my question...

The tiler was responsible for the sealing. This was also done in one piece.