The concepts for the construction of the ground floor slab can be essentially two depending on whether or not you tend to place a room under it. By placing said room it will be necessary to use a supporting structure of wooden beams of adequate size, previously treated with boron salt, anchoring them to the load-bearing walls.
On the beams will be placed of the boards and then a screed can be made with a mixture of trass-lime and cork in chips. A laying of insulating materials may be applied to complete the finishing of the walking surface.
Concrete joists can also be used, duly propped up. Above them will be placed the tables suitable to create the floor, and then make the screed and finish of the floor. It is advisable to lay large, very large boards, generally found in German-speaking countries.
In both types of construction it is necessary to provide air vents for the ventilation of the room below. Do not place any rooms you will need to take such measures that prevent the rising of moisture and the leakage of any infiltration of radon gas.
It will therefore be necessary to create a ventilated cavity known as a common vespaio which, by means of special ducting, can permit the creation of drafts. Also in this case it is possible to proceed in two ways using wooden beams or other materials.
Using wooden beams the same will be anchored to the wall leaving an inner tube below them, follows the laying of brick tiles on which a screed will be laid and the flooring.
Using the concrete you can proceed by creating walls with ventilation holes on which to place the pots or you can resort to special formworks to lose said iglu.