Planning by general contractor or independent architect?

Hello everyone,
thank you very much for your quick and detailed feedback. We will carefully work through the suggestions and information you have given us. In any case, you have helped us a lot!

That is plausible but not quite proper, unless you buy the plans. I would reject pricing a third-party plan whose rights are not clearly with the customer. If you find a company that makes an offer based on such a plan, you know you have a building partner who is willing to play dirty. Not great either if problems arise – and they always do in construction.
My advice: forget the idea.

The architect of the mentioned construction company did not explicitly speak of buying the plans, but he mentioned that if we had plans prepared by him and ultimately decided on another general contractor, we would be charged €2000. I think this procedure is common?
From your response, however, I gather that it is probably not standard to approach competitors with a construction company’s plans? What would be the alternative without involving an independent architect? Would every construction company from which we want to request an offer create completely their own plans, so that we would have to go through the entire design and planning phase multiple times?

Would every construction company from which we want to request a quote create completely their own plans

Plans yes. Really intensive work on the plans? No. You get a draft thrown at you. No one will do the work of an architect for air and love as payment. And please always remember. A "plan" is just a floor plan. For a house, it is only one puzzle piece and doesn't say anything about prices. Nor about quality or equipment.

Would every construction company from which we request an offer create completely their own plans so that we would have to go through the entire design and planning phase multiple times?

I'll just chime in here – I was reading earlier, but don’t have everything in mind anymore.
Not every construction company/general contractor offers the same. Usually, it’s the small regional ones who will plan an individual house for you. But usually with an external architect*, who must be paid extra. The in-house architect of most GCs that advertise model houses only offers modifications included. But that can often be enough for a livable house.
*You can also choose the external architect yourself.

Offers without contract are generally only made using a flat factor for a model house. If you say you want a 160 city villa, you get 160 x factor y as an offer.
If it should be the 200 sqm 3-gable house, you get 200 x factor z as an offer. Everything then includes the corresponding construction service description in standard design.
The GCs have their tables for that. They can also select the 3-meter sliding door on top or a dormer of 125cm.
Special designs and individual offers are only explicitly calculated after signing the contract.
If you have special requests that are uncommon, a GC is usually not suitable, as the subs usually don’t want to do that for a bought dumping price. This then affects construction quality.
Just as they have their tables, they also have their grids and limits. For example, our neighbor could not build his Heinz von Heiden model bungalow longer than 150 cm (or something like that).
If you don’t take a “turnkey model house” that includes architectural services (i.e., modifications), but explicitly an “individually planned” one, then you have to plan a special item “architect fees.”

Additionally, the standard GCs usually don’t offer an expandable roof. Often it’s planned in because you don’t know better.

For example, we had a GC where the managing directors were two architects. Either you chose a model house, then you also got a bit more than small modifications. Outside the model-appropriate building envelope without taking over the load-bearing wall, there is additional planning effort.

Not every well-known or supra-regional GC (or hardly any) takes on the planning of an independent architect. This is because they calculate their prices based on the model house. That is their concept; nothing else fits in there.

Regarding offers and comparisons: it’s also flawed or not. If you want a KfW 40 house as an offer, you will get it. But how it is calculated: each GC offers individually with their preferred wall construction. What do you want to compare there?

The general contractor/subcontractor can also be just as much an amateur, and normally you don’t have a getting-to-know phase or multiple possible exit points like with the architect. If you sign with the (GU), you are practically bound to them until the end (theoretically you can get out in the middle with compensation for damages, but people don’t do that because generally no one can be found who will take over another bungler’s work along with the warranty, do it well, and stay within the previous cost framework). Anyone can be a GU or GÜ! No qualifications are needed at all. I can go to the trade office on Monday and register a construction business. Either I act as a GÜ, then just gather all the specialists, tack 20% onto everything and have your house built. Or I do the flooring work and the doors and windows myself (no master craftsman requirement) and may rightly call myself a GU. With the keyword Fleischerhaus, there is a thread here where exactly such an unqualified GU was involved. The thread starter fought her way through her duplex house with sweat, blood and tears, wore out some contractors and lawyers in the process, and as far as I know is still waiting for money from the first offenders. My GÜ, a civil engineer by profession, who even received a half recommendation here in the forum, proved to be incompetent (called himself a developer, although he was not one), not very customer-oriented and untruthful (did not keep promises). His subcontractors ranged from reasonably competent but stubborn and inflexible to criminally incompetent (missing masonry overlap dimensions) and also included a heating engineer who diva-like ended the cooperation because I asked too many questions (fortunately at the end, since he also botched work at the neighbor’s place). Maybe because of my experience I swing to an extreme, but I would never build again with a GU/GÜ or recommend it to anyone (not even myself), unless you have known each other personally for years or are family and trust each other blindly (and even then I would think long and hard about it). That means only in a relationship where you can rely on the person to fix any botching by subs or their own tradesmen at their own expense if necessary and never lie to you. Then I would build with or recommend that person as a GU/GÜ.

I may be swinging to an extreme because of my experiences

I agree with this "extreme," because ours, despite visible references and also basic friendliness, ultimately really had little idea and repeatedly failed with his planning software, which he used as a civil engineer for his planning work. I won't even start listing drastic events but in fact, at some point you are simply "trapped," and during Corona, it was probably significantly more unpleasant. One was repeatedly fobbed off with the worry that he or one of his craftsmen would just give up, and these were all small, local craft businesses he worked with. Water/ventilation was abysmal and no coordination with the planner, no clue about the equipment, and therefore constant phone calls to the respective hotlines, settings always only on "auto." I rescued a mason hanging between beams, drunk, from the wall (allegedly circulation...), I clearly developed a "grain allergy." Too many windows, then too big, then too small after cutting. In the end, we looked for craftsmen for him because supposedly they all had no time. In the local construction area, we were overtaken and pitied by everyone by months. Enough. It doesn't have to be this way but it can be, so there's probably no standard version of building. The electrician was really very good, I mean that seriously, but he actually stood us up 25 times appointment-wise, and that's not an estimate. Today, living in the beautiful house, that is largely gone, but at the time, we really wanted to throw in the towel a few times.