Pre-hung doors and methods of installation therefor

A pre-hung door assembly, comprising:

• a) a frame containing parallel, spaced apart, vertical hinge side jamb and lock side jamb, a horizontal header connecting top ends of the jambs, and a sill connecting bottom ends of the jambs;
• b) a door slab hingedly mounted to the hinge side jamb in a closed position, the door slab contains opposing inner and outer surfaces;
• and
• c) at least one door jamb margin holder comprising
• i. a rectangular, flat first terminal portion,
• ii. a rectangular, flat first profile portion having a first end and a second end, the first end of the first profile portion is attached to the first terminal portion and extends perpendicularly therefrom,
• iii. a rectangular, flat connector portion having a first end and a second end, the first end of the flat connector portion extends perpendicularly from the second end of the first profile portion,
• iv. a rectangular, flat second profile portion having a first end and a second end, the first end of the second profile portion extends perpendicularly from the second end of the connector portion, and
• v. a rectangular, flat second terminal portion having a first end and a second end, the first end of the second terminal portion extends perpendicularly from the second end of the second profile portion,
• wherein the first terminal portion and the connector portion clip to the door slab and lay adjacent to and coplanar with the inner and outer surfaces, respectively, of the door slab and the first and second terminal portions clip to the lock side jam.