in a simple way see (image 1 ) that showing name of layer syntax that should be in your Autocad files you send it to us and sure to get your result you are looking for
Image 1 Ground Syntax
To draw the cement floor, it must be ensured that the shape is closed curves, whether it is a floor for the entire floor or floors for each room separately in the same layer.
In the case of gaps such as elevators, ventilation or staircases, and the like, the location of the gap is drawn in the same layer within the boundaries of the floor see (image 2).
Curves and lines must be closed
Image 2 Example ground layer