When buying land in France there are a number of situations when it is advisable or even obligatory to commission a 'géomètre expert' to measure and mark the boundaries of the property.
When buying a parcel of land in a 'lotissement' (housing estate) from a developer, this will have been done already and the boundaries clearly marked and expressed in square metres when setting the selling price of the parcel of land.
The seller of an isolated plot of land has no obligation to have the boundaries marked but must inform the purchaser whether this has been done or not. Without precise marking, it is impossible to define the exact boundaries of the land - something that is important if you plan to construct a building close to the boundaries as this will be subject to strict norms regarding distances from a neighbour's property. In some cases, a contravention can result in an order for the building to be demolished.
The boundaries marked on the local 'cadastral plan' can sometimes be out of date and inaccurate, and cannot be used in evidence in the case of a legal dispute. The purchaser is therefore advised to have an accurate survey done by a 'géomètre' in order to establish the precise boundaries of the property.
In a recent case, a litigious neighbour insisted that a brick garage be 'moved' as it was a few centimetres too close to his property. And in another, mains services that were described as 'on the boundary of the property' were found in fact to be 30 metres away, leaving the owner with a considerable bill to have then connected to his property. In this case, all parties were relying on an out of date 'cadastral' plan provided by the Mairie! It may require a court case to establish who was responsible for the mistake, should the new owner wish to recover his costs.