Core drilling is probably the most common specialist concrete work on UAE high-rises — Liberty drills over 1,500 cores per month across Dubai and Abu Dhabi. Yet many project managers don't have a clear picture of what it can and can't do, or when it's the right choice versus a saw cut or a chased slot.

This guide covers every main application of diamond core drilling on UAE construction projects.

What core drilling produces

A core drill removes a cylinder of concrete. The bit — a steel tube with diamond segments on the cutting edge — rotates while advancing into the concrete. The removed core comes out as a solid plug, leaving a clean, finish-quality circular hole.

The key word is circular. Core drilling is the right method when you need a round hole. For rectangular openings, you need a saw.

Application 1: HVAC penetrations

The largest single use of core drilling on UAE high-rises is HVAC — supply, return, refrigerant and condensate lines dropping through floor slabs.

Typical sizes:

  • Condensate drops: 50–75mm bores
  • Refrigerant pipes: 75–150mm bores (often sleeved pairs)
  • Supply/return drops: 100–200mm for individual units; up to 400mm for large AHU spigots

Volume on a typical tower: A 40-floor residential tower might have 800–1,200 HVAC bores from slab to slab. Core drilling at volume — 20–30 bores per day per crew — is significantly faster than any cutting alternative.

Application 2: Plumbing risers

DWV (drain, waste, vent), cold water supply, hot water, and fire system risers all pass through floor slabs at specific locations.

Plumbing bores are typically 100–300mm depending on the pipe size and whether a sleeve is required. The bore must be positioned precisely — typically within ±10mm of the MEP drawing location — to hit the riser shaft void.

Post-tension consideration: Plumbing risers almost always penetrate post-tension slabs. Every bore location must be GPR-scanned before drilling to verify no PT cable is in the cutting path.

Application 3: Electrical and data penetrations

Power conduit drops, low-voltage cabling, fibre risers, and telecom trunking all need penetrations through floor slabs. Sizes range from 50mm (single conduit) to 150mm (conduit bundle sleeves) to 300mm+ for large cable tray penetrations.

In Grade A office fit-outs, the finish quality of the bore matters — sleeve edges are visible at ceiling level and need to be clean for fire-stopping inspection.

Application 4: Structural anchors

Chemical anchors for structural connections — staircase railings, mezzanine columns, lifting beam supports, façade brackets — all require drilled holes.

Typical anchor sizes: 20–75mm diameter, 200–500mm deep.

Accuracy requirement: Chemical anchor positions are structurally critical. Our rigs are laser-aligned to ±2mm from the marked position. After drilling, each hole is cleaned, photographed and handed over with a drilled-hole log for the structural engineer's records.

Application 5: Concrete sampling

Core extraction for structural assessment — pulling 100mm or 150mm diameter cores from walls or slabs for compressive testing, carbonation depth measurement, or chloride analysis.

This application is common in:

  • Assessment of existing structures before renovation
  • Dispute resolution where concrete quality is questioned
  • Insurance and safety assessments on older UAE buildings

The core is labelled, packaged, and delivered to the testing laboratory. Liberty can arrange testing through accredited UAE labs.

Application 6: Manhole and utility connections

Tap connections into existing buried infrastructure — manhole bases, sewer pipes, drainage channels — often require core drilling from above. Bores of 150–300mm are typical.

This work is often done in confined spaces or with limited access, where our battery-powered rigs (no exhaust) are the only practical option.

Application 7: Stitch drilling (large openings)

For openings larger than 600mm — or where wall saw access is restricted — stitch drilling is used: a series of overlapping cores that together create a rectangular or irregular opening.

Stitch drilling is slower than a wall saw for standard door openings, but it's useful in confined spaces where a wall saw track can't be anchored, or where the cut shape isn't rectangular.

GPR before every core

The GPR pre-scan is not a luxury — it's the minimum standard of care for core drilling on any post-tension slab or any element where you don't have confirmed as-built locations of PT cables.

Nicking a PT cable is a structural event. The cable snap releases stored energy equivalent to a small explosion, and the loss of pre-stress in the surrounding bay can cause immediate slab distress. On PT slabs, every bore position is scanned before any bit touches the concrete.

On conventional RC slabs, GPR is still recommended where drawings are absent or old — we regularly find conduits, void formers, and non-standard reinforcement that aren't on any drawing.

Bore sizes and what they're used for

Bore diameter Common applications

25 – 75 mm Anchor holes, small conduits, sample extraction

100 – 150 mm Most plumbing, standard HVAC drops, conduit bundles

200 – 300 mm Large HVAC spigots, major plumbing, fire riser sleeves

350 – 600 mm AHU penetrations, large cable trays, lift shaft sleeves

Bores up to 600mm can be drilled in a single pass. Beyond 600mm, stitch drilling or a wall saw is more appropriate.

Occupied floor working

Many core drilling projects on UAE buildings happen in occupied or recently handed-over floors. Liberty's approach:

  • Battery-powered drill rigs (no exhaust fumes, lower noise)
  • Low-noise vacuum water extraction (no slurry on floor)
  • Night-shift capability where daytime noise limits apply
  • Daily hoarding and containment of drilling zone

Water management is the most common complaint on occupied-floor drilling. Our closed-loop system captures 100% of cooling water — nothing goes into drains or across floors.