What does "Sanitary pre-installation in the walls" mean

We are currently building a prefabricated house and are wavering between the construction stages "almost finished" and "almost finished plus".

Service "Almost finished" includes, among others:
Sanitary pre-installation in the walls including water distributor
Interior/exterior walls closed

Service "Almost finished plus" includes, among others:
Sanitary pre-installation in the walls including water distributor
Interior/exterior walls closed
Sanitary rooms with sanitary fixtures
Sanitary rooms with wall and floor tiles

Does anyone have experience with sanitary pre-installations in prefabricated houses? Since the walls are already closed, theoretically everything must be there. Does that mean we can simply hang the sanitary fixtures on the wall or do we have to open the walls again and install flushing cisterns, etc.?

Looking forward to feedback. If you only have to lay tiles and screw on sanitary fixtures, "almost finished" would be the favorite. We just don’t want to open the walls anymore.

Does anyone of you have experience with the sanitary pre-installations in prefabricated houses? Since the walls are already closed, theoretically everything must be there. Does that mean we can simply hang the sanitary objects on the wall, or do we have to open the walls again and install flush tanks, etc.?

Well, I do have a bit of experience. Of course, the walls are closed and nothing needs to be installed anymore. What follows now is the cooperation between the tiler and the plumber. After the rough installation, the tiles come, then the sanitary ceramics and grouting, done.

These are basic contract contents. They should be clearly described. If this is unclear to you, it is initially good to ask here.

But even if assessments are given here, they are not part of the contract. The company can interpret it differently than the forum, and unnecessary discussions would arise.

Use the forum but clarify everything with the company. Depending on the relationship, definitely also in writing.

I assume that the contract contains more than "sanitary rooms with sanitary objects," etc.?

Thank you very much for your feedback. An inquiry has revealed:

The installation walls are fully executed with the corresponding pre-installations for WC, washbasin, shower, etc. The washbasins, WC, fittings, etc. are connected or mounted on the pre-installations.

I understand this now as meaning that I "only" need to procure or mount the sanitary fixtures, as Vicky Pedia also wrote.

Does anyone perhaps still know how the installation walls are constructed in prefabricated buildings? I assume that they are also built as timber frame walls and not from the usual drywall profiles? That would not make any sense for assembly in the factory hall.

While I would have had no doubt whatsoever about the word in your first question (and would not have thought of a foolish prank either)

Maybe someone still knows how the installation walls are constructed in prefabricated buildings?

this should be explicitly stated in the construction performance description, at least the general wall structure as well as in the sanitary area and the note then from the installation wall to the sanitary wall.

Hi

once the walls are all closed and the rough installation is finished, please make sure that the connections also match the sanitary objects selected by you, any desired [UP-Armaturen] are installed, and reinforcements for the washbasin, mirror cabinet, and others are present.
if it is supposed to look really good, the tile dimensions for the rough installation are already crucial.

Olli