It depends. In accordance with article 8, para. 1 of Law No. 65-557 of July 10, 1965, the co-ownership regulations determine the destination of the private and common sections, as well as the conditions of their enjoyment. Each co-owner can freely enjoy his private partitions, subject to not infringing the rights of other co-owners and the destination of the building (art. 9 law n°65-557 of July 10, 1965).
The regulation may contain a bourgeois housing clause which requires the co-owners to use their lots only for residential purposes, thus opposing the exercise of a professional activity.
However, a tolerance is allowed when the bourgeois housing clause is “ordinary”. In this case, the latter is allowed to exercise a liberal professional activity subject to any nuisances which has been generated (Cass. Civ. 3rd, July 8, 1980). However, it excludes any commercial or artisan activity.
On the other hand, exercising a professional activity, including a liberal one, is incompatible in the presence of an “exclusive” or “absolute” bourgeois housing clause.