Process and system for installing replacement door

A system for installing a door slab in a door frame. The system comprises an adaptable door mounting support configured to acquire a door gap and to support the door slab at a height off of the ground equal to the door gap. The door mounting support includes a frame member and at least one tie device provided to meter the door gap and hold the door slab in place off the ground at the height equal to the door gap. The frame member includes two A-shaped segments interconnected by a bottom section and together defining a door support channel therebetween. The at least tie device includes a cable tie extending across the door support channel and a locking tab attached to the cable tie by sliding the locking tab over the cable tie. The locking tab is lockable on the cable tie.