Slab Scanning Sydney
Find what is inside a slab before you core, cut or drill
Slab scanning shows you what is cast into the concrete before anyone puts a core drill, saw or anchor bit into it. Locate & Map scans slabs across Sydney with ground penetrating radar, imaging reinforcement, post-tension cables, conduits and voids in real time and marking them straight onto the surface in front of your crew. The scan takes a fraction of the time a repair would, and it is the difference between a clean penetration and a very bad afternoon.
If you are penetrating a suspended slab, a post-tensioned deck or a structure with services cast into it, the scan is not optional in practice. It is the step that makes the penetration safe to sign off. Our concrete scanning service also covers walls, columns and decks; this page is about slabs.
What’s included in slab scanning?
Post-Tension Cable Detection
GPR detects post-tension and pre-tension cables ahead of the cut. We mark the tendon paths on the slab, along with the rebar and any services in the way.
Rebar and Mesh Mapping
For structural work we map the reinforcement across the area you nominate: bar spacing, cover depth and layer arrangement, to support strengthening design, condition assessment and remedial planning.
Conduits and Voids
The scan picks up pipes, conduits and electrical wiring cast into the slab, plus voids, cracks and deterioration that affect where you can penetrate.
Safe Penetration Zones
We mark the zones where a core or cut can be made without touching tendons, rebar or services, so the person holding the drill sees the same information as our operator.
Plans When You Need Them
Where the job needs documentation, our in-house drafting team issues the scan as a plan in 12d, DWG or PDF, the same formats we use for utility mapping.
Why one clear point is not a clear hole on a post-tensioned deck
Post-tension cables carry the load in a modern suspended slab. Cutting one is a life-safety event and a structural failure at the same time, and the remediation cost on a live site is severe.
Tendon paths curve through the slab, so a single clear reading does not mean the whole hole is clear. That is why, on post-tensioned decks, we scan the full penetration footprint rather than a single point, and mark the clear zones before anyone starts drilling.
GPR suits this work because it needs only one face of the slab, no exclusion zone, and gives the result on the spot. Many people search for concrete x-ray when what they need is a GPR scan; we explain the difference in concrete x-ray versus GPR scanning.
Book slab scanning across Sydney
Tell us the slab type, what you are penetrating and when you need it done. Our 24 hour service means scans can be done outside occupied hours in live buildings. Call (02) 8753 0049 or request a slab scan.
When do you need a slab scan?
Three jobs account for most of the scanning we do. Before coring: plumbing and electrical penetrations, riser holes and drainage, where the hole has to land where the reinforcement is not.
Before cutting: saw cuts through slabs and decks for openings, stairs and lift shafts, because a saw does not stop when it finds a cable. Before drilling: anchor bolts, hold-downs and fixings for balustrades and plant, because even shallow drilling reaches mesh and conduit.
What affects what a slab scan can see?
Our ground penetrating radar uses a higher frequency antenna for concrete, which resolves fine detail such as bar spacing but does not travel as far. Lower frequency antennas reach deeper with less detail, so our operators select the antenna against the target, which is why we ask what you are looking for before we quote. Heavy reinforcement, high moisture content and dense mesh all reduce what the radar can see through.
Where a slab is accessible from one face only, GPR can also indicate its thickness from the return off the back of the slab, but how well that works depends on the concrete. We confirm on site what is achievable rather than promising a result in advance. An anomaly on screen cannot always be identified on its own, so our operators record a confidence level against each target.
What you get after the scan
Our scans are read live on site. Marks go straight onto the concrete: tendon paths, rebar, services and the zones that are clear to penetrate. Where the project needs a record, the scan is issued as a plan through our in-house drafting team in 12d, DWG or PDF, ready to drop into the workflow of whoever needs it, whether that is an engineer, surveyor, architect or project manager.
You get more than the location of the steel. You also get an indication of the quality and integrity of what is there, which is what lets a structural engineer make a call on where the penetration can safely go.
Our locator surveyors are CertLoc accredited, with more than a decade of Sydney work from residential to major infrastructure, and the same crews handle GPR scanning in the ground and in the slab. If your project also has buried services around the structure, our utility locating service covers the ground outside the building envelope.