Stitch Drilling Reinforced Concrete Foundations in a Confined Area

Example of stitch drilling procedure to isolate and remove formidable reinforced concrete foundations in a confined area. After cutting into manageable sizes, the isolated blocks were lifted out on an A-Frame prior to removal.

Stitch drilling is the technique of drilling a row of overlapping diamond-cored holes to form a continuous slot through reinforced concrete. Where saw cuts are blocked by existing structure, services, or restricted access geometry, stitch drilling cuts a perimeter that a saw could not reach. The bit diameter and overlap are sized to the depth of cut and the stiffness of the rebar layout.

The method is slower than direct sawing but it works almost anywhere — including under, around, and behind retained features. Once the perimeter is cored, the isolated block is lifted clear; in confined spaces an A-Frame gantry is the usual rigging arrangement because it can be assembled inside the work area without external crane access.