To fix the issue the doors need to be removed bottom of the jambs cut and reset the door.
Standard gap between exterior door and floor.
The typical prefit for the lock stile hinge stile and head is 1 8 inch 3 mm measured on the widest face of the door.
There is a 1 5 inch gap between the threshold and the bottom of the wooden door.
That is a lot of room for unlevel you have there.
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.
The usually are 1 2 to 3 4 inches thick.
A gap of 4 cm is allowed for convenient and safe door opening.
Except for fire doors i am aware of no standards for the gap or amount of prefit on a door either interior or exterior except as established by the individual door manufacturer.
Reasonable gap between exterior door and threshold.
In addition most trim carpenters hold the bottom of the door 1 above hardwood floors to accommodate any rugs that may get put on the floor.
I have never seen a door set with that big of a gap unless it was to get past floors that were not level.
Most entry door frames have a piece of lumber below the door and combined with the metal threshold will raise the base of the door off the concrete or wood sub floor by approximately 1 1 4 inches as shown in figure 2.
Craftsmanship standards on the other hand tend to want the gap below the door to be as small as 1 2 at times but this leaves no room for rugs.
Nfpa 80 s clearance dimensions apply to the entire perimeter around and under the doors and between paired doors.
The most common solution is to add wood planks to the floor not the door.
It is more effective to leave 4 mm and more for rooms with high humidity and for doors made from materials absorbing well moisture.
They are specialized moldings usually about 3 to 6 inches wide with tapered edges.
I ve just paid a series of professionals to measure order install and paint a pre hung exterior door.
The standard i use is 1 2 over finish floors 3 4 is acceptable.
They are centered under the door and reduce airflow and noise.