Precast concrete is everywhere in the UAE. Villa compounds, warehouses, schools, car parks and boundary walls are often built from panels and slabs cast in a factory and lifted into place. Abu Dhabi even has a dedicated safety code of practice for pre-cast construction, reissued in February 2026 (ADPHC).
Sooner or later, those panels need holes for pipes, ducts and cables. Coring precast looks the same as coring cast-in-place concrete, but it isn’t. Here are the problems that make precast different, and how to deal with each one.
Problem 1: Prestressing strands
What’s going on: Many precast floor units, such as hollow-core slabs, are prestressed. High-strength steel strands are tensioned in the factory and locked into the concrete. They give the unit its strength.
Why it matters: Cutting a strand releases its prestress and weakens the unit. It can’t be fixed by filling the hole.
Solution: Never core a prestressed unit without approval from the precast manufacturer or the project’s structural engineer. Scan with GPR concrete scanning to locate strands, and position cores between them.
Problem 2: Hollow cores and webs
What’s going on: Hollow-core slabs have long voids running through them, separated by solid concrete webs. Strands usually sit in the webs.
Why it matters: A core through a web can cut strands and weaken the section that carries load. A core through a void usually removes less material.
Solution: Small cores are often positioned through the voids, not the webs, but the manufacturer or engineer should confirm. Larger openings may need a steel trimming frame or a different slab layout.
Problem 3: Sandwich wall panels
What’s going on: Many precast wall panels in the UAE are sandwich panels: two layers of concrete with insulation in between, held together by connectors or ties.
Why it matters: A core cuts through both concrete layers and the insulation. If it cuts a connector, it weakens the link between the layers. An unsealed core also lets heat, moisture and insects into the insulation layer.
Solution: Scan to find connectors. Sleeve the hole fully through both layers, and seal both faces so the insulation layer is closed off.
Problem 4: Hidden connections and inserts
What’s going on: Precast panels have steel plates, lifting inserts, dowels and connection hardware cast in. These hold panels to each other and to the structure.
Why it matters: Coring through a connection can weaken how the panel is held in place.
Solution: Check the precast shop drawings, which show every insert and connection, and stay clear of panel edges and joints. Scan to confirm.
Problem 5: Spalling on the finished face
What’s going on: Precast panels often have a finished architectural face, such as smooth, textured or coloured concrete.
Why it matters: As the bit breaks through, it can blow out a chunk of the finished face. That damage is very visible and hard to repair invisibly.
Solution: Drill from the finished face where possible, ease feed pressure near breakthrough, or core partway from each side. Protect the finished face during the job.
Problem 6: Water getting in
What’s going on: External precast panels rely on sealed joints and an intact skin to keep water out.
Why it matters: A new core through an external panel is a new way in for rain and humidity.
Solution: Use a weatherproof sleeve and sealant on the outside face, sloping pipes outwards where possible.
The right order for precast coring
- Get the precast shop drawings
- Ask the manufacturer or engineer about prestressed units and connections
- Scan each location
- Choose the position: between strands, through voids, clear of connections
- Protect the finished face
- Core with controlled feed near breakthrough
- Sleeve and seal both faces
If anything about the unit is unclear, start with a structural analysis.
Core cutting in precast with Scan and Core
Scan and Core scans and cores precast panels and slabs across Abu Dhabi and Dubai. See our concrete cutting and coring services.
Contact Scan and Core to discuss your project, or call +971 56 861 9006.
