Anyone who builds a prefabricated house in Germany soon learns the word Sonderwunsch, special request. The building description fixes the standard specification. The guide site fertighaus.de puts it simply: Abweichungen davon sind Sonderwünsche, departures from it are special requests. They usually cost extra. The examples are familiar to every builder: more sockets and data connections, underfloor heating instead of radiators, Parkettfußboden anstelle standardmäßig Laminat, parquet instead of the standard laminate. Changes agreed before signing always belong in the building contract.