Is it possible to determine the eligible costs based on a rough estimate?

I would say that every construction project can go well or badly. We chose our architect because he said right at the beginning how much it would cost at most. And it actually cost a little less, even though we still made changes and slight upgrades. He even planned an additional conservatory.
Additionally, building with an architect was several tens of thousands of euros cheaper than the cheapest offers from general contractors.
Therefore, such statements should not be made in general.

I am not saying that an architect builds more expensively than a general contractor. On the contrary... I am sure if we had built OUR! house exactly the same with a general contractor... it would probably have cost another 100k more.

If the architect is good, he starts directly with a realistically high budget. Then most probably run away Myself included... if we had talked about today's figures at the beginning, we probably a) would not have been capable and b) would not have built with an architect. In retrospect, I am glad that we didn't know and seriously underestimated it In the end, we are now getting our dream house.

Exactly this statement I have now received from 2 acquaintances as well. They had compared several prefab houses, GCs, and 2 architects. The estimate from the architect was about €20,000 lower than the cheapest comparable offer. In the end, they came out €5,000 above the estimated price. I assume that overall they were still cheaper than with the GC. Of course, not universally, but it can definitely turn out this way. You just have to clearly define the boundary conditions beforehand.

We also build with individual contracts, but we do not have an architect, rather a construction engineer. However, that should not make much difference, because the construction engineer is also supposed to bill according to HOAI. In our case, though, this is not the case. We do not pay the fee according to HOAI. Our construction engineer himself says that he would never get contracts around here if he actually billed according to HOAI. We live very rurally, far from any big city.

Our construction engineer initially told us his fee, which is also based on the house price, but as mentioned, it is not calculated according to HOAI. We then agreed on this fee as a fixed price, so that we have planning security. So if we choose finishes, his fee does not increase.

Of the pure house costs + garage (without other costs such as fees, fees, house connections, outdoor facilities, etc.), we pay him only about 4.5 % for all service phases. Including structural engineering and surveyor, it is just under 6 %. Yes, that sounds cheap. It is, but as mentioned: very rural area, the clocks here tick a little differently. Overall, the whole construction here is somewhat cheaper than elsewhere in Germany, that's my feeling...

Additionally, building with an architect was several tens of thousands of euros cheaper than the cheapest offers from GCs.

That will probably be the case for us as well. “Probably,” because we have just started building and of course, I can only say at the end whether it really was. In my opinion, our construction engineer has planned quite realistic costs and created a realistic cost estimate based on actual offers obtained from the actual executing companies. So it already takes into account almost everything we want, such "extras" as colored windows, electric shutters and partly venetian blinds, barrier-free shower, realistic electrical equipment (sufficient number of sockets, etc.), a reasonable ventilation system... so almost everything has been considered, only with sanitary fixtures we know that we will definitely upgrade there and we have planned the costs for this from the beginning.

Also neighbors who built with him and are almost finished confirmed that his cost estimates are realistic, as long as you don’t suddenly do a major upgrade (which depends on yourself and not on the architect). Of course, there will certainly be additional costs for us as well, because one wants this or that upgrade. But that should not be too much, since our construction engineer has planned the cost breakdown rather generously, so there is still a little buffer for each trade in the cost breakdown and as mentioned almost everything we want was already planned anyway. Since we informed ourselves very early before the construction, we knew from the beginning of the planning what we want and what we don’t. There should actually be no major upgrades (except sanitary). In case of emergency, we also still have our additional buffer for unforeseen things and upgrades. But for major upgrades, we would not have the money. We are normal earners with an average income (certainly earning quite a bit less than the average here in the forum) and with average wishes. Our house will be a completely normal average house without particularly upscale fittings. We don’t want more.

Offers from GCs were all significantly (!) above the cost estimate of our construction engineer. That’s why we also chose the path of individual contracts. In this region, it is normal anyway to build with an architect and individual contracts. Only very few houses here in the region are built with a GC, the absolute majority build with an architect. Precisely because it is (here) cheaper to build with an architect. This makes a difference of several tens of thousands of euros! But as I said: we have just started building and of course I cannot put my hand in the fire that it will actually stay that way in the end. So you have to trust your architect a bit that he knows what he is doing and in the end hasn’t planned the costs completely unrealistically. You naturally have more cost certainty with a GC, which for us, however, would probably have been the more expensive way. We will talk again in a year.

Thank you for your detailed response. Although our construction project is located within the [Einzugsbiet] of Stuttgart, I am confident that a fee lower than the [HOAI] is also possible here. At least an acquaintance confirmed this to me, but it was already 6-7 years ago when he built. I will report on what I was able to achieve.

One last question: How do I find a good architect in my area? So far, we have been recommended one through acquaintances, but we are not yet 100% sure. Another one we met through the [Musterhauszentrum in Fellbach], but we are also not sure about them yet. Searching online is quite difficult. Either the websites do not exist, or they do not appeal to me, at least regarding the references. And trying out every single one is quite time-consuming. Since we are building in an existing residential area, it is not like you can just ask the neighbors who they built with.

One last question: How do I find a good architect in my area? So far, we have been recommended one through acquaintances, but we are not yet 100% sure about them. We also met another one through the Musterhauszentrum in Fellbach, but we are still unsure there as well. Searching via the internet is quite difficult. Either the websites do not exist, or they do not appeal to me, at least regarding the references. And trying each one out is quite time-consuming. Since we are building in an existing residential area, it’s not like you can just ask the neighbors who they built with.

You want a good architect and he should also work a bit below price. All this in times of a mega construction boom... I wish you good luck!