The architect is wrong with the estimates. And now?

Too bad, no feedback.

Good evening! Thank you very much for all the explanations and background information.
For clarification: We had already seen the offers from different shell builders beforehand and then, after consulting with the architect, chose the cheapest one. However, it is clearly above his original estimate. He says: "Unfortunately, that's how it is. Costs are rising. They are all well-off and have endless orders, etc."
We are just wondering: Do we have to accept this? Or did the architect not do his job well enough (accurately enough)? If the architect partly bears responsibility due to inaccurate calculations: Can something be deducted from him in the end?
The good news: Of course, we had factored in a buffer, but we had intended it more for realizing upgrades and not to compensate for too low calculations.

Thank you for the feedback. With sharply rising market prices, calculations can sometimes be off – and depending on the region, building costs have risen significantly over the last 5 years. Apparently, your architect underestimated this. Of course, you cannot hold him responsible for that; the consequence would have been to reject the design and adjust it according to the budget. It’s good that there is no precarious situation due to the cost increase. Once you are in the house, it is quickly forgotten. Money often comes back.

We had already seen the offers from different shell builders beforehand and then simply took the cheapest one in consultation with the architect.

So when did you get the offer? - that doesn't really sound like a tender by the architect.

And when was the architect's calculation? One should consider, the billing according to HOAI is based on his calculation, right? If he had calculated 400000 instead of 300000, you would also have to pay the architect 1/4 more, right?

Construction prices have risen significantly in the last 5 years. Apparently, your architect underestimated that

Did the architect only oversee one construction project or why could he be so mistaken, maybe because he then earns more..