What gap is needed between door, floor and frame : Gap Doors
Quote from Article entitled What gap is needed between door, floor and frame:
Sometimes when you close a door (especially an old wooden door) the gap is too narrow or there are no gaps at all. Firstly, make sure that it is not about deformation: a frame should be exact on the level and keep the angles and diagonals configuration. In this case, it is possible:to clean off the paint;to remove a leaf from its hinges and cut contours by a plane to form a right hinge.
On the other hand, if a door dried out during the life and decreased in size, too wide gaps(over 6 mm) certainly appeared between a frame and a leaf. In this case, a door probably hangs on hinges or a knob latch misses the connector. The situation can be corrected if:you move the door up, rearranging the hinges to eliminate redundant upper gap;you fix a piece of wood to the end of the door on a hinge side, to eliminate too wide gaps.
The full version of the article can be found here.