Jack Hole

What is a Jack Hole?

Definition of Jack Hole in Construction
The hole drilled at the base of an elevator pit, to accept the hydraulic piston, that raises the elevator cab up through the elevator shaft.

The jack hole is normally drilled by a reciprocating hammer drill or rotating drill, of 8″ to 12′ diameter. This operation must be done prior to the construction of the structure, to enable the drill rig to maneuver to the required location. One of the important aspects of drilling the jack hole, is the proper layout of the position of the hole, as well as the accuracy of the vertical orientation of the hole drilled. It is important that the hole be drilled accurately to allow the elevator to properly function. The jack hole is then filled with a casing and a piston for the elevator. In most cases, sand is placed between the casing and the piston assembly to ensure a strong and stable installation.