Experiences with building an architect at a fixed price?

It is not stated anywhere yet. I asked, still no response from the OP.

Sorry, I couldn't reply during work.

As it was explained to me in the first conversation, I conclude the contracts directly with the trades.
The billing should then proceed as follows:
The trade completes its work --> Architect (or possibly his site manager) checks the execution --> if everything is fine, the corresponding service is paid by me.

Admittedly, I didn't question this in detail during the first conversation, but I definitely wanted to delve deeper into it in the next meeting. I will also bring up the point mentioned earlier regarding the "architect's services according to HOAI" and have a sample contract provided to me.

As it was explained to me in the first conversation, I conclude the contracts directly with the trades. The billing is supposed to be like this:

And if the trades become more expensive, you have to pay because you are the client? How is that supposed to work? Either you conclude a contract with the architect and he is your contract partner at a fixed price (then gladly also individual trade contracts, which you can help determine). Then you can also commission a general contractor. Or you commission the architect, he carries out his service phases = normal architectural construction. I would not accept such a construct that is being offered to you. Why? All trades become more expensive because the tender was not correct and you have to accept change orders with cost increases. The architect takes off and takes your "fixed price" with him. But you have to pay the trades because you are the client and not the architect.

I will also take up the point from earlier regarding "architectural services according to HOAI"

I have repeatedly read in this forum the opinion that the HOAI is binding, and that despite originally agreed lump sum fees, the architect can later reconsider and claim additional payment; in my opinion, lump sum fees are effectively agreed upon. I am not a lawyer, and therefore cannot assess which faction is correct.

What I am sure about, however, is that a construction contractor's service may include architectural services, but not vice versa. Essentially, this has to do with the clear distinction of the privileges of freelancers, but also with the professional liability of the freelancer, which should not have to deal with the construction contractor's warranty.

First of all, thanks again for the previous answers! At least it confirms for me that I wasn’t just insecure for no reason.

What speaks for him is that he’s been working with the model for over 10 years and only uses proven regional craftsmen (that’s probably why he can estimate the costs relatively well). A few houses in various shell construction phases that I have seen so far also looked decent at first glance, as far as I can judge as a layman. He doesn’t advertise but relies solely on word of mouth. As I said, everything made a decent impression, but of course you can’t buy anything from that in the end if the contractual part doesn’t fit...

I will definitely have a sample contract sent to me and then ask more specifically how the whole thing works contractually. Your tips have already been quite helpful so far.

And if the trades become more expensive, you have to pay because you are the client? How is that supposed to work?

Valid question, I will definitely follow up on that.

only works with proven local craftsmen

By the way, exactly this sentence is also told to you by every general contractor, whether mid-sized from your city or operating nationwide.

Warranty then runs separately through the individual trades, I assume? The advantage compared to self-awarding seems to be very small then. The architect only acts as an intermediary for the craftsmen. With the "fixed price" I would be afraid that it is just some behind-the-scenes haggling that the architect arranges with the craftsmen. Whether you can seriously rely on that in an emergency is questionable. On the other hand, the architect has a very strong interest in getting everything done cleanly with his "model" and is probably more committed than a normal architect: "well, sorry, it just got more expensive" your general contractor architect can’t afford that so easily, otherwise his word of mouth is gone.