Every concrete demolition project carries the same hidden risk: what is inside the concrete you are about to cut. Rebar is the easy part. Post-tension cables, live electrical conduit, pressurized water lines, and abandoned services that never made it onto record drawings are the dangerous part. Ground-penetrating radar removes the guesswork before demolition begins.
CDS offers pre-demolition GPR scanning as a standalone service and as the first step of our own concrete demolition scopes. Either way, the output is the same: a clear map of what is inside the concrete, marked on the slab or wall before the first saw cuts.
Why Scan Before Concrete Demolition
- Prevent post-tension strand hits. Cutting a PT cable under tension is a life-safety event. Scanning eliminates the risk.
- Keep live services live. Conduit, data, gas, and water lines hidden in walls and slabs can be routed around — but only if you know they are there.
- Protect structural reinforcement. Cutting through a critical rebar mat can compromise the structure you are trying to modify. GPR lets you plan the cut line around reinforcement patterns.
- Speed the demolition. A scanned site is a confident site. Crews work faster when they know what they are cutting into.
What GPR Maps on a Pre-Demolition Scan
- Rebar size, spacing, cover depth, and mat orientation
- Post-tension cables and anchor heads
- Electrical conduit, data lines, and low-voltage cabling
- Plumbing — supply, drain, and hydronic heating
- Embedded steel, inserts, and historical repair patches
- Voids, delaminations, and slab-thickness transitions
- Buried utilities beneath slabs and footings
Our GPR services page covers the full scope of concrete imaging beyond demolition planning.
Our Pre-Demolition Scanning Workflow
1. Review demolition drawings
Before we scan, we review the cut lines and demolition scope. That tells us where we need high-confidence data and where a quick pass is sufficient.
2. Grid and scan
A cart or hand-held GPR unit runs orthogonal passes across the demolition area. Rebar shows first; PT strands register deeper and tighter; conduit and plumbing appear at their own characteristic depths and spacings.
3. Mark on the slab
Findings are marked in crayon or paint directly on the concrete. Each line type gets its own colour; depths are written alongside. Demolition crews work from the concrete, not from a plan they have to re-consult every cut.
4. Report where scope requires
Engineering, municipal, and insurance scopes get an annotated PDF report with scan images, depths, and site photographs.
When Pre-Demolition Scanning Is Mandatory
On post-tensioned structures, scanning is non-negotiable. Most engineers, general contractors, and insurers now require GPR scans before any penetration on:
- Elevated parking garage decks
- Bridge decks and abutments
- Post-tensioned slabs in commercial buildings
- Hospital, lab, and data centre floors over live services
- Any concrete older than 30 years where record drawings are incomplete or missing
GPR as the First Step in Integrated Concrete Demolition
Most CDS projects package the scan with the concrete demolition or removal scope so one crew handles the entire sequence: scan, cut, lift, haul. That single-source approach is faster than splitting the scan across a separate locator firm — the crew that cut the scan is the crew that respects the marks.
Utility Locating Combined With GPR
For buried utilities below a slab to be demolished, GPR alone is not the full picture. We pair GPR with electromagnetic utility locating so both metallic and non-metallic services get found. This matters on demolition projects that go below grade — pad removal, foundation demolition, underground vault decommissioning.
Why CDS for Pre-Demolition GPR
Scan quality depends on operator experience more than equipment brand. CDS operators scan concrete every week across the full range of Ontario projects — shopping mall slabs, hospital floors, bridge decks, industrial foundations. That pattern recognition is what separates a useful mark on the slab from a best-guess flag. Fifty-eight years of concrete work under one roof.
Serving Hamilton and All of Ontario
From our Hamilton shop at 276 Ferrie St E, crews reach Burlington, Oakville, Mississauga, Toronto, Brampton, Kitchener-Waterloo, Guelph, Cambridge, St. Catharines, Niagara, London, and every point between. Same-day GPR scanning is routine across the GTA and Golden Horseshoe.
Pre-Demolition GPR FAQ
How long does a pre-demolition scan take?
A single cut location takes minutes; a full wall or slab area can take hours depending on size and complexity. Most projects are scanned in a single mobilization.
Can you scan right before the demolition begins?
Yes. Same-crew scheduling means the scan can happen an hour before the first cut — marks are fresh, the layout is still on the slab, and the demolition team has context from the scanning operator.
What if the scan finds something that was not in the drawings?
That is exactly why we scan. Demolition pauses, the condition is reported to the engineer of record, and the scope adjusts — a re-routed conduit, a relocated cut line, or a change order for abatement if the find is hazardous.
Do you provide scan reports for insurance?
Yes. Annotated PDF reports with scan imagery, depth measurements, and methodology are available where the project scope requires documented output.
How much does a pre-demolition GPR scan cost?
Depends on area, complexity, and whether a written report is needed. Most commercial scans are flat-rate; large facility surveys are quoted by area. Call (905) 529-6029 for a same-day quote.
Scan before you demolish — book a pre-demolition GPR survey
Concrete Drilling & Sawing Ltd. (CDS) has served Hamilton and all of Ontario since 1967. Licensed, insured, and ready to mobilize on short notice — residential, commercial, and industrial.
Phone: (905) 529-6029 | Toll-Free: 1-800-241-5708
Shop: 276 Ferrie St E, Hamilton, ON L8L 3T7 · View on Google Maps
This service falls under our scanning services. Below are the most directly related services from the same team — and a couple from our other practice area when the work overlaps.
Related Services
If the scope of your project also touches the areas below, this is where to start:
- our full-scope demolition
- Ontario demolition contractor
- our utility-locating service
- concrete X-ray imaging
Sometimes a project also calls for:
Quotes by phone: (905) 529-6029 (Hamilton) or 1-800-241-5708 (toll-free across Ontario).
Based in Hamilton, CDS serves projects across Ontario — see our areas we serve across Ontario, including concrete contractor service in Peel Region, Waterloo Region and Hamilton.