How do you search for a suitable property developer?

Well, I am a bricklayer and electrician myself, and I have more than enough time (vacation), which has already been confirmed. Maybe I am underestimating it now, but what could really go wrong if I install one more drywall partition?

A drywall partition is not the topic, but turning 3 rooms into 4? Also all drywall? Definitely consult a structural engineer to see if it’s feasible without problems. Depending on where the toilet is supposed to go, also think about the drainage. Don’t want it running straight through the living room.

I only know that this weekend we are laying empty conduit in a prepared raw ceiling and there are two of us and we could still need two extra days.

The thread starts off sluggishly, you have to ask the OP a bunch of questions before the reason and purpose of the question are even understood. Asking for a "house" in a house-building forum is a dead end! Yes, it is a house-building forum. Nevertheless, asking for a developer/construction company/general contractor leads to the same outcome.

BUs/GUs/GÜs/BT are indeed often regionally represented – reasons for choosing one or another usually come from a good gut feeling, word of mouth, regional decisions, or definitive contract terms.

We have no idea what is valued: does the BU have to be inexpensive, regionally represented, or match its own design?

Also, the statement: the plot of land is available but must be included in the financing, is confusing.

Reaching out and comparing: you can’t let a forum do that... especially not if you have to extract information from yourself. Many important things have not yet been said – and it is very exhausting for a forum to ask further questions.

A drywall is not the topic, but turning 3 rooms into 4? All drywall as well? Definitely consult a structural engineer to see if it's feasible without problems. Depending on where the toilet is supposed to go, also think about the drainage. You don't want it running across the living room.

The drywall would run once across the living room..... and the bathroom would then be directly above the kitchen, utility room, and HAR. Well, it doesn't matter now, we're not building with the "company" anymore.

I only know that this weekend we will lay empty conduit in a prepared raw ceiling and there are two of us and we could still need two extra days.

How many meters of conduit do you need to lay, from where to where? From my own experience, I know it goes quite fast. Lay, connect, and done.

BUs/GUs/GÜs/BT are indeed often regionally represented - reasons for one or the other are usually based on a good gut feeling, word of mouth, regional decisions, or definitive contractual contents.

there are certainly also enough that operate supraregionally, which is why I asked here with which "companies" good or bad experiences have been made.

when I read it like this: moved in January 2014 and still not finished I'm glad that for me it only gets laborious here in this thread ;o)