3D laser scanning or a géomètre-expert — which one does your project need?
If you are commissioning work on a building in France, you will meet two very different trades, and they are not interchangeable. A laser scanning bureau measures the geometry of what is built. A géomètre-expert is a regulated profession holding a legal monopoly on land boundaries. Choosing wrongly costs either money or a rejected file, so it is worth being precise about which one your project actually needs.
The short version
- Laser scanning captures millions of points and produces a BIM model or dimensioned drawings of the building as it stands.
- A géomètre-expert produces documents with legal standing: boundary determination, land division, cadastral filings.
- For a refurbishment, an extension or a planning submission, scanning is what you need.
- For anything touching a property boundary, only a géomètre-expert may act, and no scan can substitute.
- Roughly 300–600 € excl. VAT for a 100 m² scanned survey with drawings, against 1 500–3 500 € for a traditional surveyed measure.
Side by side
| Criterion | 3D laser scanningMeasures the building. No legal standing on boundaries. | Géomètre-expertRegulated French profession. Sole authority on boundaries. |
|---|---|---|
| Instrument | 3D laser scanner, handheld or tripod-mounted | Total station, theodolite, RTK GPS |
| How it measures | Millions of 3D points per second, whole-volume coverage | Point by point, chosen individually by the surveyor |
| Typical accuracy | ±2 to ±5 mm indoors, across the whole cloud | ±1 mm on each individually measured point |
| Main output | Registered point cloud, BIM model, dimensioned DWG drawings | Topographic plan, boundary record, site plan with legal standing |
| Legal standing | None. It is a measurement, not a certified document. | Statutory. Required for boundaries, division and cadastral acts. |
| Typical brief | Refurbishment, extension, Scan to BIM, as-built records | Boundary determination, plot division, land registry |
| Indicative cost, 100 m² interior | 300–600 € excl. VAT with dimensioned drawings | 1 500–3 500 € excl. VAT |
| Time on site | Half a day for a flat, occupants in place | One to several days depending on the scope |
Choose laser scanning when
- You are refurbishing, extending or converting, and need the building as it actually stands
- Your design team works in Revit or ArchiCAD and needs a model rather than a drawing
- The planning submission requires a dimensioned existing-conditions set
- You need to record mouldings, profiles or fabric before work alters them
- Several trades need one shared geometric base to price against
Choose a géomètre-expert when
- A property boundary has to be determined or contested
- A plot is being divided, merged or sold in part
- A document has to be lodged with the land registry
- A co-ownership division needs certified floor areas under French law
- A dispute with a neighbour turns on where the boundary legally sits
What we would do
On most building projects the two do not compete, they follow each other. The géomètre-expert settles what you own; the laser survey settles what is built on it. On an extension, for instance, the surveyor confirms the boundary and the permissible footprint, and the scan produces the model of the existing structure that the design and the planning file are built on. Commission the survey you need for the question you are actually asking.
Common questions
Does a 3D scan replace a géomètre-expert?
No, and it cannot. They answer different questions. Scanning captures the geometry of a building to produce a BIM model or dimensioned drawings. A géomètre-expert issues documents with statutory standing under French law — boundaries, division, cadastral filings. For a refurbishment, scanning is enough. For anything touching a boundary, only the géomètre-expert may act.
Which one is more accurate?
On a single point measured with a total station, a surveyor reaches ±1 mm. A laser scan sits between ±2 and ±5 mm. But the scan measures millions of points at once, giving complete coverage of the fabric, which a total station cannot do. The right question is not which is more accurate but which kind of accuracy your project needs: one precise point, or the whole building.
What does each cost?
For a 100 m² interior survey delivered with dimensioned DWG drawings: 300 to 600 € excl. VAT scanned, against 1 500 to 3 500 € excl. VAT through a traditional surveyed measure. For boundary work the comparison does not arise — only a géomètre-expert is competent, and a scan has no legal standing whatever it costs.
Can I build a BIM model from a surveyor's measure?
Rarely, and not well. A traditional measure produces 2D drawings from points measured one at a time. Those drawings do not carry the 3D geometry a workable BIM model needs. Scan to BIM requires a complete point cloud, which means a laser scanner.
For a roof extension in France, which do I need?
Both, in that order. The géomètre-expert confirms the boundary and the permissible ground coverage. The scan then captures the real geometry of the existing structure — roof, facades, structure — to produce the model the design and the planning submission rest on.
Can a scan produce the site plan for a planning file?
Yes. An exterior scan produces an accurate 2D site plan from the point cloud, and that is accepted in a French planning submission. What it cannot do is serve as a boundary record: for a deed of division, a géomètre-expert is required.