Can GPR detect rebar in all concrete?

GPR detects rebar in most concrete types and thicknesses. Signal penetration is typically 300–500 mm in normal-density concrete. Very dense or heavily reinforced concrete can reduce penetration depth. In practice, GPR reliably detects reinforcement in the vast majority of slabs, walls and columns encountered on construction and refurbishment projects.

How accurate is cover depth measurement?

The Proceq Profometer electromagnetic covermeter measures cover depth to an accuracy of ±1–2 mm in typical conditions. GPR cover depth is accurate to within ±5–10 mm depending on the dielectric properties of the concrete.

Can you detect plastic or non-metallic conduits?

GPR detects non-metallic features including plastic conduits, ducts and pipes, provided there is sufficient contrast between the conduit material and the surrounding concrete. Electromagnetic covermeters only detect metallic objects.

GPR rebar scanning survey — locating reinforcement in a concrete slab before drilling

GPR & Covermeter Surveys

Rebar Scanning and Reinforcement Detection

Locate reinforcement, measure cover depth and estimate bar size — non-destructively, before you drill, fix or alter the structure.

Call 07340 549892 Get a Quote

What we do

Rebar Scanning and Reinforcement Detection

Reinforcement detection is one of the most common pre-works surveys on construction and refurbishment projects. Before any drilling, coring, fixing or structural alteration, you need to know where the steel is — its location, spacing and depth below the surface.

ACUO uses ground-penetrating radar (GPR) and electromagnetic covermeter surveys to locate reinforcement in concrete slabs, walls, columns and beams. We provide on-slab mark-up, annotated photographs and a written report, typically within 24–48 hours of the survey.

All surveys are carried out by Gary Stringer, a GPR NDT Civil Engineer with over 20 years of experience. We are Constructionline Gold and SSIP accredited.

Full concrete scanning service Concrete scanning in London

Get a rebar detection quote

Tell us the element to be scanned, the location and what works are planned. We'll provide a fixed-price quotation, typically within 24 hours.

07340 549892 [email protected]

Send an enquiry

Detection capabilities

What We Detect

Rebar scanning and reinforcement detection surveys can identify and measure the following:

Rebar location — plan position of individual bars in slabs, walls and columns
Bar spacing — centre-to-centre spacing of the reinforcement grid
Cover depth — depth of concrete cover over the nearest bar
Bar diameter estimation — approximate bar size using the Proceq Profometer
Reinforcement orientation — direction of top and bottom mat layers
Embedded conduits and services — electrical, data and plastic pipes within the slab
Post-tension tendons — location and spacing of PT cables in post-tensioned slabs

3D GPR depth-slice image showing reinforcement layout in a concrete slab

GPR scan data showing rebar and embedded features in concrete

Method selection

GPR vs Covermeter — Which Method and When

GPR (ground-penetrating radar) and electromagnetic covermeters are complementary tools. Each has strengths, and the right choice depends on what you need to know.

GPR images the full depth of a slab in a single pass. It detects rebar, post-tension cables, conduits, voids and slab thickness simultaneously. It is the method of choice when you need a complete picture of the slab interior, when post-tension cables may be present, or when the reinforcement layout is unknown.

The Proceq Profometer electromagnetic covermeter measures the depth of the nearest steel bar quickly and accurately. It also estimates bar diameter. It is ideal when you need precise cover depth data at many points — for example, a cover survey across a large floor plate or a series of columns — and when the reinforcement is known to be conventional steel without post-tension tendons.

On most projects we use both: GPR to map the full reinforcement layout and confirm no post-tension cables are present, then the Profometer to measure cover depths at the specific locations where fixings or cores are proposed.

Proceq GP8000 GPR

Full slab imaging — rebar, PT cables, conduits, voids, slab thickness

Best for: Unknown layouts, post-tension slabs, pre-coring surveys

Proceq GS8000 GPR Array

Multi-channel 3D scanning — rapid coverage of large floor plates

Best for: Large commercial floors, car parks, complex reinforcement layouts

Proceq Profometer

Cover depth measurement and bar diameter estimation

Best for: Cover surveys, fixing locations, structural assessment data

Applications

When You Need Rebar Detection

Before coring or drilling — confirm safe zones and avoid reinforcement
Before structural fixings — anchors, bolts, brackets and hangers
Before cutting or chasing — M&E routes, service penetrations, openings
Structural assessment — cover depth data for corrosion risk and load calculations
Refurbishment and fit-out — understanding the existing structure before alteration
Dispute and insurance — independent evidence of reinforcement layout

Survey deliverables

What You Receive

On-slab mark-up of all detected reinforcement using spray paint or chalk
Annotated site photographs showing the marked-up findings
Written survey report with scan images, cover depth data and interpretation
Safe zone recommendations for proposed drill or core locations
Bar spacing and orientation data where required
Cover depth tables for Profometer surveys

Reports issued within 24–48 hours of survey as standard.

Common questions

Frequently Asked Questions

Can GPR detect rebar in all concrete?: GPR detects rebar in most concrete types and thicknesses. Signal penetration is typically 300–500 mm in normal-density concrete. Very dense or heavily reinforced concrete can reduce penetration depth. In practice, GPR reliably detects reinforcement in the vast majority of slabs, walls and columns encountered on construction and refurbishment projects.
How accurate is cover depth measurement?: The Proceq Profometer electromagnetic covermeter measures cover depth to an accuracy of ±1–2 mm in typical conditions. GPR cover depth is accurate to within ±5–10 mm depending on the dielectric properties of the concrete. For structural assessment purposes, Profometer measurements are used where precise cover data is required.
Can you detect plastic or non-metallic conduits?: GPR detects non-metallic features including plastic conduits, ducts and pipes, provided there is sufficient contrast between the conduit material and the surrounding concrete. Electromagnetic covermeters only detect metallic objects. For surveys where plastic conduits may be present, GPR is the appropriate method.
Do you mark up on the slab surface?: Yes. On-slab mark-up is included as standard with every rebar detection survey. We use spray paint or chalk to mark the position of detected features directly on the concrete surface, so your drilling or coring team can see exactly where the reinforcement is before they start.
How quickly can you mobilise in London?: For most London surveys we can mobilise within 24–48 hours of instruction. For urgent requirements, call us directly on 07340 549892 and we will do our best to accommodate you.

Related services