If each room has individual air returns the numbers can be smaller for personal taste.
Space between door and floor.
The standard i use is 1 2 over finish floors 3 4 is acceptable.
It should be measured from the floor surface to the bottom of the door.
A gap of 4 cm is allowed for convenient and safe door opening.
That is a lot of room for unlevel you have there.
To fix the issue the doors need to be removed bottom of the jambs cut and reset the door.
Between a leaf of interior doors and the floor it is required to leave a gap of at least 2 2 5 cm to provide natural ventilation.
Measure the distance between the door frames at the floor.
This number is regardless of flooring.
You simply describe the gap take a picture of it or.
I have never seen a door set with that big of a gap unless it was to get past floors that were not level.
Transfer this measurement to the threshold put on a pair of safety glasses and cut it to this length with a hacksaw or jigsaw.
This allows for proper air exchange between rooms.
During installation of a frame and during the initial formation 1 2 cm gaps should be left for foaming.
Door clearance although this is a broad term it usually refers to the space between the top of the door and header rabbet or bottom of the door and finished floor.