PROPERTY — ENCROACHMENT
You have just received a registered letter. Your neighbor in Antibes claims that your new fence encroaches 15 centimeters onto his land. Astonishment. You take out your tape measure, measure from the corner of the party wall. Result: 0 cm encroachment, the fence is exactly on the boundary. Who is right? In 9 out of 10 cases, both tape measurements are wrong. The truth lies beneath your feet, buried in the official boundary marking, and only a contradictory tacheometer survey can reveal it.
What You See — and What It Really Hides
You see two owners, each with a tape measure, numbers that don’t match. The conflict seems simple. What you don’t see is the fundamental reason: a property boundary is not a line drawn on the ground. It is a series of georeferenced points in space, defined by coordinates (X, Y, Z) in the RGF93/Lambert 93 system (French geodetic system). Your corner wall? It may have moved over time. The ground? It is not perfectly flat. Measuring with a ruler from a supposedly fixed point is like navigating at sea with a faulty compass: errors accumulate.
What I often observe on site, especially in old Antibes or sloping neighborhoods, is the cumulative effect. A wall that is not perfectly straight (+2 cm), an uncompensated slope in the measurement (+5 cm), an approximate reading of the tape (+1 cm). The total error can easily reach 10 to 20 cm over a distance of 15 meters. Frankly, this is the norm, not the exception. You and your neighbor are probably both measuring from different starting points, or using methods that introduce bias. The true starting point is the geodetic marker or the notarial boundary point, not your wall corner.
The Equation of Truth: Root Mean Square Error
To settle the matter, we do not average the two measurements. We calculate the deviation between the actual fence position and the legal boundary position. The key is the Root Mean Square Error (RMSE). It quantifies the overall measurement precision by cumulating all uncertainties. The formula is: RMSE = √(σ₁² + σ₂² + … + σₙ²), where σ are the standard deviations of each error source.
Let’s take a concrete case in Antibes. Suppose the legal boundary is defined by two survey points 20 m apart. I perform a tacheometer survey with a Leica TS16 (angular accuracy: 1″, linear accuracy: ±2 mm + 2 ppm). Error sources: reference point setup (σ_ref = 0.005 m), sighting on the fence (σ_sight = 0.003 m), thermal deformation of the instrument (σ_temp = 0.001 m). The RMSE becomes: RMSE = √(0.005² + 0.003² + 0.001²) = √(0.000025 + 0.000009 + 0.000001) = √0.000035 ≈ 0.0059 m, about 6 mm.
Now, I measure the distance between the fence and the legal boundary. Result: Δ = 0.14 m (14 cm). The measurement uncertainty (RMSE) is 0.006 m. So the encroachment is 0.14 m ± 0.006 m. What this means concretely: the encroachment is clearly established, because 14 cm is far greater than the 6 mm margin of error. The accepted tolerance for this type of boundary survey is generally around 2 to 5 cm. Here, it is outside tolerance. Article 545 of the French Civil Code (Code civil) is clear: “No one may be compelled to yield his ownership, except for public utility…” An encroachment is an infringement on that ownership. Article 555 deals with constructions built by a third party on another’s land and the compensation due. Paragraph 1 applies directly: if the fence is built on the neighbor’s land, even in good faith, the neighbor may demand its demolition or claim ownership against compensation.
Letting It Slide: The Bill Doubles in 5 Years
If you do nothing, thinking “it will work out,” you expose yourself to a certain escalation. Within 6 months, the conflict will worsen. Neighborly discussions turn into lawyer letters. After 2 years, if the neighbor takes the case to the Grasse Judicial Court (competent for Antibes), costs accumulate: bailiff fees for constat, expert fees, legal fees. After 5 years, the total can easily double compared to an early resolution. A contradictory tacheometer survey, costing around €1,500 to €3,000, is a fraction of what you would pay in court. Moreover, the court will likely order such a survey anyway. So why wait?
📅 Mis à jour le 18/08/2026 — Par Cassini Expertise, expert bâtiment indépendant 06 & 83. Devis gratuit : 04 22 46 06 04.
Questions fréquentes
What is fence encroachment?
Fence encroachment occurs when a fence or structure extends beyond the legal property boundary onto a neighbor's land or public right-of-way. In Antibes, this often leads to disputes requiring precise land surveys to resolve.
Why did the tacheometer survey contradict in Antibes?
A tacheometer survey may contradict earlier measurements due to differences in equipment calibration, surveyor technique, or reference points. In the Antibes case, the contradiction highlighted the need for a more accurate total station or GPS survey to establish the true boundary.
How to resolve a fence encroachment dispute in Antibes?
To resolve a fence encroachment dispute in Antibes, first obtain an official land survey from a licensed surveyor. If the survey confirms encroachment, you may need to negotiate with the neighbor, seek mediation, or take legal action to have the fence moved or adjusted.