Is boundary marking (bornage) mandatory for a building permit?

An owner planning to extend a house, build a garage or build on the edge of a plot almost always asks the same question when putting the application together: should a surveyor be brought in to mark the boundary before the application is filed at the town hall? The answer is often surprising, because in the vast majority of cases the authorities grant the permit without requiring a boundary survey plan. Even so, the absence of boundary marking can turn a perfectly authorised project into a legal nightmare, where the wall or foundation encroaches by a few centimetres on the neighbouring land. This article sets out the situations in which boundary marking is actually required before a permit, those in which it remains optional but strongly advisable, and the concrete risks of a building permit without prior boundary marking.

Boundary marking and building permits: two distinct legal logics

Before turning to the obligation, it must be understood that boundary marking and the permit belong to two different areas of law, pursuing objectives that do not overlap.

What boundary marking involves

Boundary marking (bornage) is the operation that definitively fixes, on an adversarial basis, the dividing line between two adjoining private properties, and then marks it with reference points (the boundary markers). It belongs to private property law. Article 646 of the French Civil Code sets out the founding principle:

Every owner may oblige his neighbour to have the boundaries of their adjoining properties marked. Boundary marking is done at common expense.

Boundary marking makes sense only between adjoining private plots that have not already been delimited. It does not apply to the boundary with public land (a road, a pavement), which falls under an alignment order issued by the local authority. In concrete terms, boundary marking answers the question: where exactly does my land end and where does my neighbour's begin?

What the building permit involves

The building permit is an administrative planning authorisation, governed by the French Town Planning Code. The town hall (or the competent authority) checks that the project complies with the applicable planning rules: local urban plan (plan local d'urbanisme, PLU), siting, height, footprint, external appearance, parking, distances from boundaries. It checks the project's compliance with public development rules, not ownership of the land.

This distinction is essential: the authority that examines the permit never rules on whether the applicant is in fact the owner of the land, nor on the exact location of the boundaries. The permit is always granted without prejudice to the rights of third parties. This wording, set out in the decision, means that the authorisation does not prejudge the neighbours' property rights in any way and does not protect against a civil action.

The principle: no mandatory boundary marking to obtain a building permit

There is, in the French Town Planning Code, no general obligation to produce a boundary survey report in support of a building permit application. The documents to be attached to the file are exhaustively listed by the French Town Planning Code (the regulatory part on the content of authorisation applications), and the boundary plan is not among them.

The file rests on a location plan, a site plan and an elevations plan, which the applicant may draw up personally or have drawn up by an architect or a surveyor. The site plan must of course locate the building in relation to the boundaries of the plot, but nothing requires those boundaries to result from adversarial boundary marking. They may come from the land register (cadastre), which it must be remembered is a tax document and not a title to property: the cadastral line has no legal value for fixing a boundary.

The principle is therefore clear: a building permit without boundary marking is perfectly regular under planning law. The town hall cannot refuse a permit solely on the ground that the land has not been marked. It examines the file as presented to it, relying on the boundaries declared by the applicant.

This principle explains why so many buildings are authorised and then built without any surveyor having defined the boundary: obtaining the permit did not trigger any land check. The problem, as will be seen, arises afterwards, when the neighbour challenges the actual siting.

Cases where boundary marking becomes unavoidable before building

Although the principle is one of freedom, several situations make boundary marking either legally mandatory or indispensable in practice. This is precisely the angle that should guide any project owner.

Land arising from a subdivision or a division

This is the clearest case of obligation. Where land comes from a subdivision (lotissement), the boundary of the lots was necessarily defined by a chartered land surveyor (géomètre-expert) at the time of the division into plots, and the boundary marking appears in the development permit file. Article L. 115-4 of the French Town Planning Code moreover requires, for the sale of land arising from a subdivision (or from a land consolidation, or from a joint development zone) and intended to receive a dwelling, that the description of the land result from boundary marking.

In other words, in this scenario, mandatory boundary marking for a building permit is not a constraint of planning law at the time of filing, but a consequence of the regulated division of the land upstream. The purchaser of a lot therefore knows the marked boundaries, which secures the siting of the future house. Conversely, a simple division into two of a family plot by notarial deed, outside the subdivision procedure, does not always guarantee prior boundary marking, hence the caution required.

Building on the boundary or at a short distance from it

The PLU frequently authorises building on the dividing boundary (party wall, garage abutting the fence) or imposes a precise setback, for example three metres. Yet one cannot comply with a distance of three metres from a boundary whose exact location is unknown. Where these setback rules constrain the project, the shared courtyard easement (servitude de cour commune), which makes it possible to acquire the neighbour's building rights before the permit is filed, is examined in a separate article.

Take the case of an owner who wishes to build a garage against his neighbour's boundary. If the real boundary is in fact sixty centimetres inside what he believes to be his land, the garage wall will encroach to that extent on the neighbouring land, even though the permit was properly issued. Here, boundary marking is not legally mandatory to obtain the permit, but it becomes a precaution that any legal professional will describe as indispensable. Building as close as possible to the boundary without boundary marking amounts to building blind.

Uncertain or already disputed boundaries

Where the boundary has never been fixed and the physical clues are blurred (an old hedge, a ditch, a low wall whose exact position relative to the dividing line nobody knows), prior boundary marking is in effect necessary. The same is true if a neighbourhood dispute already exists, or if the neighbour has expressed disagreement over the location of a fence.

In these cases, filing a building permit without boundary marking amounts to building on a disputed boundary, with the risk that the land dispute attaches itself to the project and blocks the site. Boundary marking then allows the question of the boundary to be cleared up before any work begins.

The concrete risks of a building permit without prior boundary marking

This is the heart of the matter: what does a person who builds after obtaining a permit, but without having had the boundary marked, really risk? The consequences can be serious, because the right of property is protected with great rigour.

Encroachment: the risk of demolition

Encroachment means that a building extends, even slightly, onto the neighbour's land. French law treats encroachment with particular severity, because it infringes the right of property, defined by Article 544 of the French Civil Code as the right to enjoy and dispose of things in the most absolute manner, and because Article 545 recalls that no one may be compelled to give up his property, except for reasons of public utility.

The case law of the Cour de cassation is consistent and particularly strict: encroachment, even of a few centimetres, justifies demolition of the structure. The judge need not assess the builder's good faith, nor the minor nature of the overhang, nor the disproportion between the cost of demolition and the harm suffered. The victim owner may demand restoration, that is, the removal of the part that encroaches.

A regular building permit offers no protection here. Since the authorisation is issued without prejudice to the rights of third parties, it does not prevent the neighbour from bringing an action before the civil court. An owner may therefore have built in complete administrative legality and nevertheless be ordered to demolish a load-bearing wall because it overhangs the adjoining land by a few centimetres. Prior boundary marking is the only way to rule out this risk, since it fixes the boundary in a manner binding on others.

Disputes with the neighbour and blocking of the site

Even where no encroachment is established, the absence of a defined boundary opens the door to litigation. The neighbour who challenges the siting may apply to the court, request a court-ordered expert appraisal, and seek a stop to the works in summary proceedings (référé). A site suspended for several months while an expert determines the boundary disrupts the operation, increases its cost and durably weakens neighbourly relations.

Judicial boundary marking then takes place in the worst conditions: after the works, under the pressure of a dispute, with the risk that the boundary defined by the expert does not match the one the builder had assumed. It is always better to mark the boundary calmly, upstream, than in the heat of a lawsuit.

Legal distances and easements to be observed

Boundary marking also conditions compliance with neighbourhood rules that have nothing to do with planning but are equally binding. The planting distances laid down by Article 671 of the French Civil Code, or the rules on views over the neighbouring land, are calculated from the dividing boundary. Article 678 of the French Civil Code requires a distance of one metre ninety between a direct view (window, balcony) and the boundary, and Article 679 a distance of sixty centimetres for an oblique view.

These distances are measured from the dividing line. Without boundary marking, an owner may believe he is complying with the legal distance for a window or a terrace, and then be ordered to block up the opening because the real boundary was closer than he thought. Here again, the building permit does not protect: it does not examine easements under private law. The distances applicable to windows and balconies and the remedies available against the neighbour are set out in our article on the easement of view (servitude de vue).

Amicable or judicial boundary marking: how to secure your boundary

In the face of these risks, boundary marking follows two routes, which it is useful to know before launching a project.

Amicable boundary marking is the normal route. The two owners call on a chartered land surveyor, the only professional authorised to fix property boundaries. The surveyor studies the titles, the land register and the physical clues, hears the parties, and then draws up a boundary marking report signed by both sides. Once signed, this document has strong legal value: it fixes the boundary definitively between the signatories and their successors in title. Boundary marking is done at common expense, as provided by Article 646 of the French Civil Code, each owner bearing half the surveyor's cost.

Judicial boundary marking takes place where one of the neighbours refuses to take part, disputes the proposed boundary or refuses to sign the report. The diligent owner then applies to the judicial court (tribunal judiciaire), which most often orders an expert appraisal. The appointed expert proposes a boundary, and the judge decides by a boundary marking judgment. This route is longer and more costly, which argues, once again, for boundary marking in advance, before the project crystallises tensions. The choice between the amicable route and court action in the face of a neighbour who disputes the boundary is analysed in our article on boundary disputes between neighbours.

An important nuance must be stressed: boundary marking fixes the boundary, it does not transfer any property. If an encroachment is found, boundary marking reveals it but does not regularise it. Regularisation then requires either demolition or an amicable agreement to transfer a strip of land, formalised by notarial deed, which the neighbour remains free to refuse under Article 545 of the French Civil Code.

Practical advice before filing a permit application

The analysis leads to a clear position: legally, boundary marking is not a condition for the grant of the building permit, but it should be regarded as a common-sense prerequisite as soon as the building comes close to the boundaries of the plot.

A few reflexes make it possible to secure a project:

• check the origin of the land in the title deed, to find out whether it comes from a subdivision (in which case it is already marked) or from a simple division that has not been marked
• never rely on the cadastral line alone to site a building close to a boundary, as that line has no legal value
• have amicable boundary marking carried out by a chartered land surveyor before any project on the dividing boundary or at a short setback, and before any wall, fence or terrace
• keep the signed boundary marking report, which will constitute evidence binding on others in the event of later dispute
• consult a surveyor as soon as there is any doubt about the location of a hedge, a ditch or an old wall supposed to mark the boundary

The cost of prior boundary marking is out of all proportion to that of a demolition ordered by the judge or of a site blocked by summary proceedings. It is a preventive expense, not a luxury.

Conclusion

The building permit and boundary marking answer two different questions: one says whether one may build under the public planning rules, the other says how far ownership extends. No general obligation requires boundary marking to obtain a permit, and a building permit without boundary marking is perfectly regular. But this administrative regularity masks a major land risk: since the permit is issued without prejudice to the rights of third parties, it offers no protection against the neighbour's action, and encroachment, however minor, exposes the owner to demolition. Boundary marking is truly unavoidable upstream only for land arising from a subdivision, but it becomes a decisive precaution as soon as one builds close to a boundary.

The recommendation is simple and firm: before any project on a boundary or at a short distance from it, have amicable boundary marking carried out by a chartered land surveyor and keep the signed report. Never let a cadastral plan stand in for a legal boundary. Faced with a neighbour who disputes the boundary, or with an uncertain boundary, have your title to property analysed by a lawyer before filing your permit application, rather than after the foundations have been poured.

Frequently asked questions

Is boundary marking mandatory to obtain a building permit?

No. No provision of the French Town Planning Code makes the grant of a building permit conditional on production of a boundary marking report. The town hall examines the file on the basis of the plans supplied and the boundaries declared by the applicant. The only case of upstream obligation concerns land arising from a subdivision, already marked at the time of the division, Article L. 115-4 of the French Town Planning Code requiring a description resulting from boundary marking for their sale.

Can one build on land that has not been marked?

Yes, nothing legally prohibits it. But building on unmarked land, in particular close to a boundary, carries a risk of encroachment on the neighbouring land. The Cour de cassation requires demolition of any structure that encroaches, even by a few centimetres, regardless of good faith. Prior boundary marking is therefore strongly advisable as soon as the building comes close to the dividing boundaries.

Does a building permit protect against an action by the neighbour?

No. The permit is always issued without prejudice to the rights of third parties, which means that it does not rule on ownership of the land or on the location of the boundaries. A perfectly lawful permit does not prevent the neighbour from applying to the civil court for encroachment and obtaining demolition. Protection against this risk comes not from the permit but from boundary marking.

Is the cadastral plan enough to define the property boundary?

No. The cadastre is a tax document intended to form the basis of the property tax, and it has no legal value for fixing a property boundary. Only boundary marking, carried out by a chartered land surveyor and recorded in an adversarial report, establishes a boundary binding between neighbours. Relying on the cadastral line alone to site a building on the boundary exposes the owner to encroachment.

Who pays for boundary marking between neighbours?

Boundary marking is done at common expense, as provided by Article 646 of the French Civil Code. The cost of the chartered land surveyor is in principle shared equally between the two owners concerned. If one of the neighbours refuses to take part, the other may bring judicial boundary marking proceedings before the judicial court, the apportionment of costs then being decided in the course of the proceedings.

What is the risk if the building encroaches on the neighbouring land?

The neighbour may ask the court to order demolition of the part that encroaches, and the judge orders it even for a minor overhang. The right of property, protected by Articles 544 and 545 of the French Civil Code, cannot be forced: the neighbour is never required to give up a strip of land, even against compensation. Amicable regularisation by notarial deed remains possible, but requires the neighbour's agreement, which he may freely refuse.

Should the boundary be marked before buying building land?

It is strongly recommended, and sometimes mandatory. For land arising from a subdivision, a land consolidation or a joint development zone and intended for housing, Article L. 115-4 of the French Town Planning Code requires that the description result from boundary marking. For other land, boundary marking is not legally required on sale, but it allows the purchaser to know the exact area and boundaries before designing the project and to avoid later disputes.