Dry-Stone Boundary Wall Encroaching on a Neighbour’s Land in Toulon: GNSS Survey

PROPERTY LAW — FRENCH RIVIERA

You have a dry-stone wall in the Var, in Toulon, and your neighbour says it encroaches on their land. You’ve measured with a ruler, checked Géoportail, but that’s not enough. Field experience regularly shows an 18 cm gap between the cadastral plan and the reality on the ground. The difference? A centimetre-accurate RTK GNSS survey.

What You See — And What It’s Really Hiding

The wall is there, visible, built of dry stone. You assume it sits on the boundary line. But the cadastre is not a survey document. And a simple ruler or laser tape doesn’t have the precision needed to settle a land dispute. What I see time and again: the owner measures from the wall to a nearby landmark, but the slope of the land or the absence of a boundary marker hides the real discrepancy.

In Toulon, with its karstic limestone terrain and steep hillside slopes, historical boundaries are often blurred. Dry-stone walls have sometimes been shifted over the decades. Without a contradictory topographic survey, you’re left with uncertainty.

The Calculations That Change Everything: GNSS Precision and Legal Tolerance

Standard NF ISO 17123-8 sets the tolerances for GNSS surveys. In fast-static mode, the standard deviation is ±1 cm horizontal. In practice, though, with multipath effects and vegetation cover in Toulon, it reaches ±2 cm. The root-mean-square error (RMSE) formula applies: RMSE = √(σ₁² + σ₂²). With two independent measurements (your survey and your neighbour’s), the total uncertainty is √(2² + 2²) = 2.8 cm — putting the tolerance for a significant discrepancy at around 5 cm.

Article 646 of the French Civil Code entitles any property owner to request a boundary survey (bornage). Article 647 states that fences and walls must respect property lines. If your wall encroaches by more than 5 cm (beyond tolerance), the neighbour can demand its demolition. In Toulon, the Tribunal Judiciaire applies these provisions strictly. In concrete terms: a measured gap of 18 cm constitutes a clear-cut encroachment.

What Happens If You Do Nothing: Deterioration and Litigation

An encroaching dry-stone wall isn’t just a land ownership problem. Rainwater runs down the wall and seeps onto the neighbour’s land. On the Var’s shrink-swell clay soils, this can trigger ground movement. Within 2 years, it’s not uncommon to see walls crack and neighbouring foundations destabilise. The cost of repairs can reach €15,000.

In Toulon, the local zoning plan (PLU) often prohibits modifications without a permit. If you wait, your neighbour can take the matter to court and obtain a penalty of €100 per day of delay — not counting the cost of a court-ordered expert assessment, roughly €3,000 payable by you if you lose.

Remedies and Guarantees: What You Can Demand

Under Article 646 of the Civil Code, you can demand a contradictory boundary survey. Article 647 states that any encroachment must be removed. Standard NF ISO 17123-8 (section 5.3) sets the measurement tolerances. The process: send your neighbour a registered letter with acknowledgment of receipt requesting an amicable boundary survey. If they refuse, take the matter to the Toulon Tribunal Judiciaire. A land-surveying expert will carry out a contradictory GNSS survey. The judge will order demolition of the encroaching section and restoration of the site. In Toulon, expect a decision within 6 to 12 months.

Further Reading

• Shared Pool Boundary in Antibes: Land Surveying and Encroachment — What to Do?
• Pool on the Property Line in Antibes: Boundary Dispute Remedies and Article 674 of the Civil Code
• Shared Pool Boundary in Antibes: Land Surveying and Encroachment — What Are Your Options?

📅 Updated on 26/08/2026 — By Cassini Expertise, independent building expert for the Alpes-Maritimes (06) & Var (83). Free quote: 04 22 46 06 04.

Frequently Asked Questions

What is the maximum height for a boundary wall without a building permit?

Generally, a boundary wall over 2 metres high requires a building permit. Below that height, a simple prior declaration of works may be sufficient, but you should check Toulon’s local zoning plan (PLU).

How can I find out if my boundary wall encroaches on my neighbour’s land?

To find out, you need to call in a chartered land surveyor to carry out a boundary survey. High-precision GNSS measurements can be used to determine the exact property lines and detect any encroachment.

What should I do if my boundary wall encroaches on my neighbour’s land?

In case of encroachment, you should negotiate with your neighbour to reach an agreement — for example, by moving the wall or paying compensation. If no agreement is reached, the neighbour can bring legal proceedings to have the site restored.

📅 Mis à jour le 25/09/2026 — Cassini Expertise, expert bâtiment indépendant (06·83·13·40).