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Core Drilling Concrete — 45 Plumbing Penetrations (Night Shifts)

Location: GTA, Ontario (office/administration building)
Client: Repeat plumbing contractor (via GC/building management)
Services: Core drilling concrete + GPR scanning
Scope: 45 penetrations (3", 4", and selective 5" top recess)
Slab thickness: approx. 15–20" (varies)
Schedule: 3 nights (overnight work windows)

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Project overview

This core drilling concrete scope supported new plumbing lines in an office/administration building. The work area above was active, and the rooms below (first-floor storage) contained stored items—so water control and controlled core drop were the priority.

We completed 45 holes for plumbing penetrations, with hole sizes ranging from 3" and 4", plus a few locations where we created a 5" shallow top recess so drain hardware could sit flatter at floor level.

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The challenges

Controlled core drop: The rooms below were storage areas. We had to catch cores and manage water so nothing spilled or damaged stored items.
Overnight access: Work was done at night. One shift was partially lost because two rooms could not be accessed (keys were not available), pushing the remaining holes into a third night.
Embed risk + thick slab: The slab varied around 15–20", so we used GPR scanning to reduce surprises and keep drilling locations clean and intentional.
Clean handoff: Plumbers needed holes ready for immediate installation—no loose debris, no slurry mess.

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Our work

  • GPR scanning of the slab ahead of drilling to confirm conditions and reduce “blind” risk around reinforcement/embedded items.
  • Diamond core drilling using a Hilti DD-250 rig for consistent, round penetrations.
  • Controlled core drop + water control: cores were collected from below, with attention to keeping storage areas protected and minimizing runoff.
  • Hole finishing & cleanup: cores were removed, and each location was vacuum-cleaned so the plumbing crew could proceed without rework.
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The result

  • 45 penetrations completed across multiple rooms, including the final rooms opened on the third night.
  • No water damage to stored items thanks to controlled core drop, water management, and cleanup discipline.
  • Ready-for-install handoff: clean, round openings sized for the plumber’s new lines and drain detail.
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Core Drilling Concrete for Plumbing Penetrations

Practical answers about overnight drilling, thick slabs, GPR scanning, and controlled core drop in occupied buildings.

It’s diamond drilling round, accurate holes through concrete slabs or walls for pipes, drains, and sleeves—without breaking surrounding structure.

GPR scanning helps confirm thickness and identify reinforcement/embedded items so drilling locations are intentional and risks are reduced—especially on thicker slabs.

Controlled core drop means catching the core from below and managing water so nothing falls or spills into occupied/finished spaces. It’s critical when there are storage rooms, tenant areas, or sensitive finishes under the slab.

Wet coring produces slurry. The practical approach is containment + vacuum cleanup at every hole and keeping the work area workable for the next trade.

Typical ranges are 3"–4" for lines and sleeves, and sometimes a shallow larger top recess (e.g., 5") to help drains or hardware sit flush at floor level.

Address + floor/level, hole list (diameter + quantity), slab thickness (if known), access hours, what’s below the slab (finished space/storage), and photos/markups.