The Hidden Infrastructure Inside BC Concrete
Concrete slabs in British Columbia contain a wide range of embedded infrastructure — not all of it documented. Rebar and mesh provide structural reinforcement. Post-tension cables run through many slabs built after the 1980s under hundreds of kilopascals of tension. Electrical conduit, water supply lines, in-floor radiant heat tubing, data conduit and drain pipes all run through concrete at depths that vary by installation era and site.
A core drill or sawcut that hits any of these without warning creates serious consequences: severed post-tension cables require structural engineering assessment and emergency repair costing tens of thousands of dollars; cut electrical conduit creates immediate life-safety hazards; severed in-floor heat tubing floods framing cavities and voids the building warranty.
What GPR Detects
Ground Penetrating Radar scans the slab with radar pulses that reflect from material boundaries inside the concrete. A trained operator reads the reflected signal in real time, identifying:
- Rebar and mesh — spacing, depth, and orientation
- Post-tension cables — sheathed in plastic, they appear as distinct linear anomalies at consistent depth
- Electrical conduit — metal and non-metallic, both detectable
- Water supply and drain lines — including in-floor PEX radiant tubing
- Voids and delamination — hollow zones that indicate structural risk
When GPR Is Required
Any of these operations in a BC building should be preceded by a GPR scan:
- Core drilling for drains, pipes or structural bolts
- Sawcutting for drain installation, expansion joints or slab opening
- Anchor installation for mechanical equipment, mezzanines or handrails
- Excavation adjacent to or through a slab
- Demolition of a concrete slab where below-slab infrastructure is unknown
- Renovation in any building with in-floor radiant heat
Post-Tension Slabs: A Special Concern
Post-tensioned concrete slabs are common in BC residential and commercial buildings constructed since the 1980s. The cables are stressed to 200 kN or more. Cutting a post-tension cable releases this energy suddenly and can cause explosive spalling, structural movement, and immediate risk to workers. Post-tension cables are not always on drawings, and as-built drawings are often unavailable for older buildings. GPR is the only reliable way to locate them before cutting.
The GPR Scan Process
A GPR scan of a slab takes 30–60 minutes for a typical room or work area. The operator marks the surface directly above detected anomalies and their depth. Safe cutting corridors between anomalies are identified and marked. Results are available on-site immediately — no lab turnaround.
Cost vs. Risk
A GPR scan costs a fraction of the damage that results from a hit on a post-tension cable or major conduit. Most contractors and building owners who have experienced an undetected hit — even once — scan every slab as a standard part of their pre-work process. Many BC municipalities, institutions and commercial property managers now require scan documentation before issuing cutting permits.
LeakInspections.ca provides GPR scanning across British Columbia. A division of Anyleak.ca and Leak.ca — serving BC since 1999. Call 604-239-9934.