An elevator climbs and lifts loads along the length of a double ladder. The double ladder comprises a first ladder and a second ladder that join together to form an overlap portion. The overlap portion is wider and generally less stable than the individual ladders. The elevator helps overcome the physical barriers imposed at the overlap portion. The elevator utilizes guiding mechanisms having different orientations and designs to smoothly cross over misalignments and instable structures in the double ladder. The elevator includes a housing. The underside of the housing includes guide units that ride the side rails to align a first ladder and a second ladder. Rollers press the housing in contact to the ladders. Notched rollers suppress vibrations on the housing. The guide mechanisms selectively engage the ladders and the overlap portion based on the position of the elevator. A motorized platform extends from the housing.