How to commission a concrete scanning survey

Commissioning a concrete scanning survey is straightforward when you know what to ask for. Done well, you get a same-day quote, a surveyor on site within days, and a defensible report the morning after. Done badly, you get a vague deliverable that nobody can act on. The difference is in the brief and the conversation that produces it.

Here is how to commission well.

Start with the question

A concrete scan is a tool. The tool is only useful if it is answering a clear question. Before you call a surveyor, write down what you actually need to know:

• “We need to drill 15 holes through this slab and we need to know where it is safe to drill.”
• “The structural engineer needs the reinforcement layout in this column to inform a strengthening design.”
• “We suspect a void in the slab and we need to confirm or rule it out.”
• “We are altering this slab to form a new opening and need to know what is in the path of the proposed cuts.”

The clearer the question, the better the deliverable. A surveyor with a clear question will scope the survey appropriately and will deliver a report that answers the question directly. A surveyor with a vague question will either over-scope (producing more than you need) or under-scope (producing less than you need).

Provide the right information

When you call or email for a quote, include:

• The site address.
• The element to be scanned (slab, wall, column, beam) with reference to drawings or a sketch.
• The dimensions, even approximate.
• The structural type if known — RC slab, post-tension floor, masonry, or “we don’t know”.
• The history — age of the structure, any major works, any known defects.
• The brief — what question is the scan answering?
• The access — site induction, working hours, any restrictions.
• The programme — when do you need the work done by?

A surveyor who has these in hand can quote precisely and accurately. A surveyor without them is quoting blind.

Specify the deliverable

Be explicit about what you want:

• An on-slab markup, in chalk or paint, of every target.
• A PDF report with depths, layout, and photographs.
• A CAD-ready DXF/DWG plan in the project coordinate system.
• A narrative interpretation, signed off by the surveyor.
• Calibration record and method statement.

Most reputable surveyors deliver all of this as standard. Asking for it explicitly removes any ambiguity and gives you a defensible reference point if anything is missing.

Ask the right questions about qualifications

Before signing the quote, confirm:

• The surveyor’s GPR competency. EuroGPR Certified Surveyor is the European standard; ask whether the person doing the work holds it.
• The equipment to be used and its calibration record.
• The insurance position — professional indemnity, public liability, employer’s liability.
• Site-induction and PPE compliance.
• Any specific competencies for the kind of work (PT scanning, large-scale GPR, etc.).

Reputable surveyors volunteer this information. Surveyors who are evasive about it should be questioned.

Match the cost to the brief

Concrete scanning is reasonably priced for what it delivers, but the cost varies with scope:

• A small pre-drill scan of a discrete area can be a half-day job.
• A reinforcement-mapping survey of a large slab might be a full day.
• A complex PT or void investigation may need a multi-day campaign.

If the quote seems unusually low, ask why. Reputable surveyors are not the cheapest in the market because they invest in calibrated kit, qualified people, and proper reporting. A cut-price quote often reflects under-scoping that will produce an under-spec deliverable.

What to do on the day

When the surveyor arrives:

• Have someone available who can answer questions about the structure.
• Make sure the surface is clean and accessible.
• Mark up the proposed drilling/coring/cutting positions before they arrive.
• Keep an eye on the live markup — surveyors mark up on the slab as they find targets, and you can review the markup before they leave site.

The half-hour at the end of the survey, where the surveyor walks you through what they have found, is the most valuable part of the engagement. Use it.

After the report

Read the report critically:

• Does it answer the original question?
• Are the depths and positions clear?
• Are the limitations acknowledged?
• Is the deliverable in a format your downstream users can use?

If anything is unclear, query it with the surveyor before any drilling, coring, or cutting takes place. Reputable surveyors are happy to clarify.

A short checklist

Before signing the quote:

• The brief is clear.
• The information has been provided.
• The deliverable is specified.
• The surveyor’s qualifications are verified.
• The price is consistent with the scope.

Before signing off the report:

• It answers the original question.
• The deliverables are present and complete.
• The recommendation is clear.
• The surveyor has signed off.

A well-commissioned concrete scanning survey is one of the highest-value pieces of work on any reinforced-concrete project. Spending fifteen minutes getting the brief right is the best investment of project time you can make.