Architect's fee for a single-family house

Have you read and understood this?

Cases must be distinguished in which the commissioning is already unclear and disputed as to whether it is merely gratuitous acquisitive preliminary services of the architect or commissioned architect services subject to remuneration. In such a case, the pricing law of the HOAI, which always requires a contract conclusion, does not help further.

The parties were not even agreed on the most important part (the remuneration) when the architect made the inquiry. The architect only submitted the proposal to bill according to HOAI with his draft. Until then, working without a commission.

But it will not come to that here. Possibly the original poster will clarify whether he commissioned the planning service. I rather suspect not.

I rather doubt it.

The OP writes the following: "He did not mention the ideas at the beginning, but rather a free initial draft (I had not mentioned that at the start - sorry)."

If it was said that it is a free draft, then the whole thing must not cost anything at all.

Otherwise, the whole matter lacks statements about what was said by the client to the architect. Was it a first introductory meeting on the meadow or were wishes expressed and detailed planning discussed? If the architect in the first case immediately started drawing and brought the thing on his own initiative almost up to the building application, then according to my legal understanding we are probably still in the acquisition phase. If wishes and budget were discussed and in the end maybe changes were negotiated, then we are probably already deep into the service phases. This is also stated in the quoted text, but input from the client is still missing.

Our architects also initially suggested the HOAI. However, we found it difficult to know exactly which costs would come up with HOAI. Therefore, we agreed on a fixed price based on the estimated construction cost. We then agreed on about 7.5% of the construction cost. With HOAI, it would certainly have been 10-12%.

Our architects initially also proposed the HOAI. But we found it difficult to know exactly which costs would arise with the HOAI. Therefore, we agreed on a fixed price based on the estimated construction sum. We then agreed on about 7.5% of the construction sum. With the HOAI, it would certainly have been 10-12%.

Our architect wants 12.5% according to the HOAI.
However, he would generally apply this rate to the calculation and not to the actual costs. In principle, I don't find that wrong since the costs are fixed from the outset.
Does anyone have experience with this?
Additionally, there are about 25,000 incidental costs. This includes 15,000 for the structural engineering.
Service phases 1-8 ~ including incidental costs 120,000€ for a single-family house with 600,000€ eligible costs.
Is this reasonable?

When we were building our house, it was already a lot of work for the architectural firm. Creating all the tenders, etc., negotiating, and handling complaints. Creating all the drawings, submitting the building application, coordinating craftsmen, some on-site appointments. You also get to use the architect's good network for free. If I were an architect, I would also like to have that much... It is definitely a lot of stress and work. The question is how supply and demand are at the moment. With little work, the architect will probably be willing to do it cheaper to get a contract. I would try to negotiate (for example, 10% only of the house sum) or maybe otherwise ask a second architect? Good luck