GPR Before Concrete Cutting Guide — Protecting Your BC Property

Cutting, coring, or anchoring into concrete without first scanning for embedded hazards is one of the riskiest decisions a property owner or contractor can make. In British Columbia, where post-tensioned concrete slabs are common in parkades, podiums, and high-rise buildings, the consequences of striking a post-tension cable can be catastrophic — including sudden structural failure, serious injury, and tens of thousands of dollars in emergency repairs. Ground-penetrating radar (GPR) concrete scanning is the only reliable, non-destructive method for identifying what lies beneath the concrete surface before you cut.

Post-tensioned concrete is widely used in BC construction, particularly in parkades, commercial buildings, and as podium slabs supporting wood-frame residential construction. These slabs contain high-tensile steel cables that are tensioned after the concrete is poured, placing the slab under compression. Cutting a post-tension cable releases this stored energy violently — the cable can whip out of the slab with tremendous force, causing structural damage and potentially fatal injuries. Repairing a cut post-tension cable requires specialized engineering and can cost $10,000 or more per cable.

Beyond post-tension cables, concrete slabs contain a variety of other hazards. Electrical conduits carrying live power are common in industrial and commercial slabs. In-floor radiant heating tubes (PEX or Uponor) are found in many residential and some commercial buildings — cutting one releases water and creates a flood, plus a difficult repair. Data and communication lines may be embedded in slabs in office and institutional buildings. Even standard reinforcing steel (rebar), while not as immediately dangerous as post-tension cables, can damage cutting equipment and compromise structural integrity if cut in critical locations.

GPR concrete scanning works by transmitting high-frequency radar pulses into the concrete and measuring the reflections from embedded objects. Our 1.6 GHz to 2.6 GHz antennas provide detailed imaging to depths of 400-500 mm, which covers the typical range of reinforcement and embedded services. The radar creates a real-time cross-sectional image that our trained operators interpret on site. We can identify rebar position and spacing, post-tension cable location and depth, conduit and raceway paths, in-floor heating tube locations, and voids or delamination within the slab.

Best practices for GPR scanning in BC include: scanning should be performed by a trained operator with experience in the specific concrete type and construction era, the scanning grid should cover the entire area to be cut — not just spot checks — as utilities can deviate from expected paths, markings should be made on the concrete surface with permanent markers or paint immediately after detection, and depth information should be noted for each located object. Standard practice is to scan a grid that extends at least 30 cm beyond the cut or core location on all sides.

When should you get GPR concrete scanning? Any time you are planning to: core drill through concrete for plumbing or HVAC penetrations, cut concrete slabs for leak repair access, install anchors or dowels into existing concrete (e.g., for seismic upgrades, equipment mounting, or railings), saw-cut expansion joints or trench drains, or remove concrete sections for renovations or demolition. Even apparently simple tasks like drilling a few anchor holes can be dangerous if you hit a post-tension cable.

At LeakInspection.ca, a division of Anyleak.ca and Leak.ca, we provide GPR concrete scanning services throughout BC. Our technicians arrive with calibrated equipment, survey the marked area, and provide on-site markings within hours. We also provide written documentation with depth information for project records. The cost of GPR scanning is minimal compared to the potential liability of a utility strike. When you consider that the repair of a single post-tension cable can exceed $10,000 plus engineering fees, the investment in scanning is clearly justified.