Abstract: A security door system includes a door jamb, a door, and a deadbolt mechanism. The door jamb includes a soffit and an aperture defined in the soffit. The deadbolt mechanism is mounted to a surface of the door and out of a plane of the door such that a deadbolt of the deadbolt mechanism is operable to project into the aperture in a locked position. In various implementations, the deadbolt mechanism may be mounted to the surface of the door by attachment members such as bolts that extend through attachment member apertures in the door. Shock absorbent material may be variously positioned around the attachment members in the attachment member apertures and may absorb at least some shock from a force applied to the deadbolt mechanism.