A rotary drive machine for the installation of helical pile sections through installation openings in a slab floor inside of a building perimeter. A vertical frame having an upper end and an open lower end is positioned over an installation opening through which it is desired to rotationally install a helical pile section, and the vertical frame anchored to the slab floor. A rotary power means, attached to the helical pile section moves along a vertical movement guide and is driven by a vertical actuator to rotationally and vertically drive the helical section into the ground. A method of use is also disclosed.