Hello,
we have decided in NRW to build massively stone by stone. It all started with companies that offer prefabricated wooden frame constructions, as I am a fan of machine production. An offer for a 1.5-story construction in KfW 70 standard with air-to-water heat pump, complete underfloor heating and fireplace was around 230,000 euros +/- 10,000 euros depending on the provider. However, in the end we noticed that a standard house is always easy to realize in prefabricated construction and the companies, for example, charge a lot extra for a knee wall increase or a convertible attic with a full staircase. With stone by stone construction this is easier to implement since the architect simply draws it in. According to our experience, the brick cladding is also easier to realize with a solid construction method. In short: standard fits prefabricated construction, the more changes to the building envelope are planned, the more solid construction fits. At least that is my experience. You should be aware that if you want to compare offers from 3 providers each, you will spend about 3-4 months on it. Furthermore, you will notice that the salespeople have no great interest in you, the more questions you ask and the more detailed you want the offers to be. For me, it was 6 prefabricated construction companies, none of which remained because none managed to submit a proper offer. Of the two solid house builders, ultimately only one managed to deliver an offer according to our wishes with a drawing. All prices were similar and, as described above, difficult to compare due to the confusing construction and service descriptions. Hope this helps a little bit.