What Is Stitch Drilling? How to Create Large Openings in Concrete
Stitch drilling — sometimes called stitch coring — is the method used to create openings in reinforced concrete that are too large for a single core bit. By drilling a series of overlapping holes in a defined pattern, any size or shape of opening can be created with no vibration shock to the surrounding structure.
How Does Stitch Drilling Work?
A closely spaced series of core holes is drilled around the perimeter of the intended opening, then the remaining connecting “webs” of concrete between the holes are removed. Core bits from 50mm to 250mm diameter are used, with spacing and overlap adjusted to suit the concrete thickness, reinforcement layout and required opening dimensions. Pre-works ferro scanning is essential before stitch drilling — each core hole is positioned to avoid reinforcement identified in the scan.
Applications
There is no practical upper limit on the size of opening that can be created by stitch drilling. Common applications include lift shaft penetrations, large service riser openings, structural openings for new staircases, and access hatches through basement slabs. For structural openings, the works should be designed by a structural engineer who will specify the sequence and any temporary propping required.
Stitch Drilling vs Sawing
For rectangular openings in floor slabs within flat saw depth capacity, sawing is often faster. Stitch drilling is preferred where the slab contains post-tension cables, where concrete is too thick for available saws, where geometry is non-rectangular, or where access prevents a saw track being set up.
BritCut carries out stitch drilling across the UK as part of our diamond drilling and concrete cutting services. All works include pre-works ferro scanning as standard. Call us on 01322 221533 or request a free site survey.
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