These 2-storey homes can be also delivered as 1-storey – without the lower floor or adjusted in a different way.
Standard solution is the upper floor as wooden construction and the lower floor as concrete or brick material.
The number indicated in the title of the wooden house gives the area of the top floor / ground ashlar floor or concrete floor of the house in m2
( including a garage, which is the part of the object ). Ground floor, eventually partly embedded floor in the ground, is like anything else, optional.
The size of the house area can then grow according to the size of the lower floor, which can be minimal but it can be also equal to the area of upper floor, mostly without the garage. Then the area of the house can be even 75% up to 100% bigger.
Therefore such a house can be delivered as 1-storey or 2-storey.