Prefabricated house - Remove sanitary service from the service?

So if the sampling is tomorrow, then just choose the objects you can imagine. You probably won't get a price for them anyway, right? Afterwards, you can compare what you would save, talk to your [sanitärer] from your circle of acquaintances and then decide. And it's best to take photos of everything you have chosen. For me, everything in the offer was called differently afterwards, even though they were the identical objects. It's very exhausting to figure it all out again.

I am particularly worried about the concealed fittings in the shower...

Something like that obviously can't just be done separately, as it needs to be coordinated with the tiler, etc. A simple washbasin, on the other hand, is less of a problem. In the kitchen, you only get angle valves anyway, and the kitchen installer connects to those. Don't let yourself be pressured into anything. Take a look at the items during the sample selection, get the results in writing, also get an offer for installation only up to the angle valve, and then decide. I would also get items like mirrors, toilet paper holders, etc. myself and install them. For us, the limit is anything that requires drilling into tiles. If the plumber damages something, that's not my problem.

Everything that does not need to be coordinated with other trades I would gladly remove if the effort is financially worthwhile. Everything that has something to do with the tiler (including the shower drain) should remain with that contractor. And your acquaintance certainly doesn't want to come by for just the drain on one day...

Concealed fittings are difficult - we did the same (i.e. took them out), but the coordination effort is quite high. If the tiler is also supposed to come from the house manufacturer (we commissioned this separately), then it is doubly difficult - the concealed installation units must be installed at the right time so that the sealing can be carried out correctly. Your acquaintance must be able to come exactly on the day to do the installation, otherwise you will only get obstruction notices due to construction process disruptions. The same applies in the area of wastewater/drainage, etc.

What I don’t really believe, however, is that you can remove fittings etc. sporadically (e.g. shower = house manufacturer, washbasin = in-house work) - the decision will probably be either all or nothing.

Thank you for all your feedback!

and Thank you for the tip about the photos! We won’t let ourselves be pressured and will have everything shown to us tomorrow, or rather then get the price and calculate again. Rushing to take something out now would definitely be wrong.

and We will try that tomorrow, leaving in the unsightly things like the drain and just trying to remove the simple things. But it probably won’t work like that; I have no idea about a drain, but have seen a few videos about it. Sounds a bit complicated and really requires coordination and yes, our acquaintance works full-time, so the idea that he would take a day off from one day to the next just to quickly do the drain before the screed guy comes will never work...

We’ll take a look at it tomorrow and then I’ll just get back here again! Until then, thanks again and have a nice evening! I’m curious what will come our way tomorrow...

We have an appointment for our house sampling tomorrow with our house provider, so I would be very happy to hear your opinion today.

Our responsible project manager pointed out to us today that in order to save costs, we could also remove the sanitary services from the contract. This way, we could buy the fittings and such cheaper on the internet and save a lot of money, provided we find a willing installer.
[...] We simply have no idea what the worst-case scenario could look like: no pipes in the wall; no proper transfer point; the wrong connections for these fittings...

That is a fantastic idea, to quickly check the internet the evening before the sampling appointment to see if there might be forums for home builders. An even more fantastic idea is to find a foolish builder who, enticed by quick savings, lets himself get saddled with the problem of finding the plumber himself.

Standards are not the problem; I do not know any house manufacturer with special customizations. I advise against the drunken idea of relieving the house manufacturer in this way. In your region, subcontractors probably face long waiting times for appointments, and after the installation date, the manufacturer wants to have the job ready for billing quickly. Serious bodily harm or the incitement thereof is punishable, so just tell him verbally and peacefully that you already know that trick.