LAND BOUNDARIES — CÔTE D’AZUR
You bought a house in Toulon, in the La Garde district. The dry-stone wall bordering your garden has always looked a little crooked to you. One day, your neighbour shows you a cadastral map on their phone: according to them, your wall encroaches 12 centimetres onto their land. You’ve measured with a tape measure, checked Géoportail, but nothing is clear. 12 cm sounds trivial, but in property law, it’s a chasm.
What You See — and What It’s Really Hiding
The wall is old, built from dry stone, with no concrete foundation. It follows a line you assumed was the boundary. But the cadastral map has no legal value as a boundary survey. What you’re looking at may be a wall that has shifted over time, or one that was built askew 50 years ago. Frankly, without a precise topographic survey, you can’t state anything for certain.
What nobody tells you: a tape measure or a phone’s GPS gives an uncertainty of 5 to 10 metres. Not good enough. Resolving a boundary dispute requires centimetre-level precision. Field experience regularly reveals encroachments of around 8 cm once measured with RTK GNSS — one owner had lost 3 m² of land without ever knowing it. Here, 12 cm along 20 metres of wall works out to 2.4 m². Not negligible.
The Calculations That Change Everything
To measure the encroachment, we use RTK GNSS equipment with centimetre-level precision. Standard NF ISO 17123-8 defines the procedure: you set up over a known point (an IGN benchmark or a calibration point), then measure the ends of the wall. The measurement uncertainty (RMSE) is calculated as follows:
RMSE = √(σ₁² + σ₂²), where σ₁ = 1 cm (RTK planimetric precision) and σ₂ = 0.5 cm (centring error). This gives RMSE = √(1² + 0.5²) = 1.12 cm.
The tolerance for a court-ordered boundary survey is 2 cm under the French decree of 16 September 2003. Here, the measured encroachment is 12 cm — well beyond that tolerance. In practical terms, the wall must either be moved, or a right-of-way easement negotiated. Article 646 of the French Civil Code entitles any property owner to demand a formal boundary survey (bornage). Article 647 states that boundary fences and walls must respect property lines. In Toulon, these disputes fall under the jurisdiction of the local civil court.
What Happens If You Do Nothing
Time is working against you. Across the Alpes-Maritimes, clay-rich soil swells with rain and shrinks over summer. Your dry-stone wall, with no foundation, could shift even further. Within 2 years, the encroachment could grow to 20 cm. And your neighbour can bring a court-ordered boundary action: you’d then have to cover the expert’s fees (€2,000 to €5,000) — and demolish the wall on top of that.
It’s not uncommon to see cases in Toulon where an owner waited 5 years: the wall had tilted a further 15 cm, vegetation had grown between the stones, and the repair bill reached €8,000 — not counting legal fees. Acting now saves you both time and money.
Remedies and Guarantees: What You’re Entitled to Demand
You can request an amicable boundary survey. Send your neighbour a registered letter with acknowledgement of receipt, proposing to bring in a planning expert. If they refuse, take the matter to the Toulon court. Article 646 of the Civil Code gives you this right, and standard NF ISO 17123-8 guarantees the reliability of the GNSS measurements. An independent expert such as Cassini Expertise can carry out a joint survey and produce a report usable in court. Don’t delay: the thirty-year limitation period is running, but the longer you wait, the more complicated the situation becomes.
Further Reading
📅 Updated 07/08/2026 — By Cassini Expertise, independent building expert serving the 06 & 83 departments. Free quote: 04 22 46 06 04.
Further reading:
Frequently Asked Questions
Dry-stone boundary wall encroaching on your neighbour: what should you do?
If your wall encroaches on the neighbouring property, you should first check the cadastral boundaries and pursue an amicable boundary survey. If a dispute arises, take the matter to the civil court. A GNSS survey in Toulon can help establish the exact boundary line.
How much does a GNSS boundary survey cost in Toulon?
The cost of a GNSS boundary survey in Toulon generally ranges from €800 to €2,000 depending on complexity. This covers the topographic survey, coordinate calculations and the boundary report. Get quotes from several chartered surveyors (géomètres-experts) before deciding.
What is the legal setback distance for a boundary wall?
In urban areas, a boundary wall can be built right on the property line provided it complies with the local zoning plan (PLU). In rural areas, it must sit at least 50 cm back from the boundary. For a dry-stone wall, also check local regulations and any easements that may apply.
Cassini Expertise
Expert du bâtiment indépendant — Antibes (06·83·13·40)
📅 Mis à jour le 25/09/2026 — Cassini Expertise, expert bâtiment indépendant (06·83·13·40).