What can GPR detect that a cover meter cannot?

Ground penetrating radar detects non-metallic targets, plastic conduit, drainage, voids and slab edges, as well as steel. A cover meter only responds to metal, so GPR is the tool when the concern is hidden services or build-up rather than reinforcement alone.

Does GPR work on all concrete surfaces?

It works on most slabs, walls, columns and beams accessible from one face. Performance falls where concrete is very wet, salt-contaminated or heavily congested with steel, because these conditions attenuate the radar signal. We assess suitability on arrival.

Is ground penetrating radar safe to use indoors?

Yes. GPR emits very low-power radio waves and uses no ionising radiation, so there are no exclusion zones or dosimetry requirements. The area does not need to be cleared of people, unlike radiographic methods.

Can GPR scan from only one side of a slab?

Yes, and that is its key advantage. The antenna and receiver sit together on a single accessible face, so a suspended slab or a wall can be surveyed without access to the opposite side, which radiography cannot do.

How accurate is GPR depth measurement?

Depth is derived from signal velocity through the concrete, which we calibrate on site. Typical depth accuracy is within about ten to fifteen per cent. Where a critical dimension is needed we verify it against a known reference such as a slab edge or a single core.

GPR Scanning

GPR scanning uses ground penetrating radar to image the inside of concrete from a single accessible face. RebarScan provides GPR surveys across Oxfordshire to locate reinforcement, conduits, voids and post-tension cables quickly and without ionising radiation. All scanning is carried out to UKCSS-compliant standards.

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What GPR scanning is

Ground penetrating radar sends a short pulse of low-power radio energy into the concrete and listens for the reflections that bounce back from buried interfaces. Steel, conduit, voids and the far face of a slab all reflect the pulse differently, and the equipment builds those reflections into a real-time image of what lies beneath the antenna.

Unlike a cover meter, which only senses metal, GPR responds to a much wider range of targets. That makes it the method of choice where the concern is not just reinforcement but the whole build-up, plastic services, drainage, construction joints and unexpected voids.

Because the antenna and receiver work from one surface, GPR can survey suspended slabs, walls and columns where there is no access to the opposite side, and it does so without the exclusion zones that radiography demands.

When it is required

GPR is required when intrusive work is planned through a slab or wall of unknown construction, when services are suspected but undocumented, and when a structure must be surveyed without disrupting the surrounding area. On occupied or live sites its lack of a radiation exclusion zone is decisive, the work continues around it.

It supports CDM risk control by giving a fast, safe picture of the structure before cutting, and it is often the first survey on a refurbishment where the existing build-up is poorly recorded. GPR is also the core method for specialist work such as RAAC plank location, runway and bridge-deck scanning, and silo and culvert surveys.

What is detected

Reinforcement, mesh and structural steel
Metallic and non-metallic conduit and pipework
Post-tension cable ducts
Voids, honeycombing and construction joints
Slab thickness and the position of the far face

How it works

The engineer moves the antenna across the surface in a planned grid, watching the radar profile build up in real time. Targets of interest are marked on the concrete as they appear, and depths are calibrated against a known reference where accuracy matters. Data can be saved and reprocessed afterwards to produce annotated outputs. No power supply, water or surface preparation is required.

Who commissions it

GPR scanning is commissioned by contractors and M&E teams clearing penetrations, structural engineers investigating unknown build-ups, facilities and refurbishment managers working in occupied buildings, and demolition teams checking structures before breaking out.

Frequently asked questions

What can GPR detect that a cover meter cannot?: Ground penetrating radar detects non-metallic targets, plastic conduit, drainage, voids and slab edges, as well as steel. A cover meter only responds to metal, so GPR is the tool when the concern is hidden services or build-up rather than reinforcement alone.
Does GPR work on all concrete surfaces?: It works on most slabs, walls, columns and beams accessible from one face. Performance falls where concrete is very wet, salt-contaminated or heavily congested with steel, because these conditions attenuate the radar signal. We assess suitability on arrival.
Is ground penetrating radar safe to use indoors?: Yes. GPR emits very low-power radio waves and uses no ionising radiation, so there are no exclusion zones or dosimetry requirements. The area does not need to be cleared of people, unlike radiographic methods.
Can GPR scan from only one side of a slab?: Yes, and that is its key advantage. The antenna and receiver sit together on a single accessible face, so a suspended slab or a wall can be surveyed without access to the opposite side, which radiography cannot do.
How accurate is GPR depth measurement?: Depth is derived from signal velocity through the concrete, which we calibrate on site. Typical depth accuracy is within about ten to fifteen per cent. Where a critical dimension is needed we verify it against a known reference such as a slab edge or a single core.

Related services and coverage

Need a GPR survey?

Describe the structure and the works planned, and we will scope the survey for you.

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