Prehung door unit structure

A door unit structure designed to close an opening made in a wall, extending vertically and separating or delimiting two spaces in a building comprising:

• a prehung door unit made up of at least one door leaf, installed to pivot by at least two hinge plates, each one provided with a fixed part and a movable part, about a vertical axis;
• a door frame including two vertical stanchions and an upper transverse crosspiece, the prehung door unit being able to engage in a recess made in a thickness of the wall of the opening;
• and
• a pre-frame able to be mounted in the recess of the opening, and held and locked in position in the recess by respective anchoring and sealing, the pre-frame including a fixation support for the prehung door unit such that the door unit is fixed in an immovable manner in the opening by a rigid and detachable connection.