So, I have now spoken with my insurance guy. If less than a year passes between the purchase of the land and the start of construction, the purchase price of the land must be included (which almost doubles the premium for me). Because the insurance assumes that, in connection with the land, there can also be legal disputes. Waiving this and possibly ending up underinsured in case of disputes would have been a risk, which is why I have now had this adjusted. Damn, the (money) box is rattling.