I think there is a fairly simple answer to this question: it all depends on the complexity of the project and the condition of the property.

For a complete interior design project, construction site supervision is generally essential. The more customised the solutions, the more questions tend to arise during the works.

This is particularly true in older apartments. In Paris especially, buildings often reveal surprises once work begins: uneven walls, outdated services, structural constraints or technical elements that were invisible during the first visits.

Even the most detailed drawings cannot anticipate every situation discovered after demolition or during construction.

But construction site supervision is not about being permanently present on site. Its purpose is to check that the project is being interpreted correctly, answer technical questions, adapt certain solutions when necessary and coordinate decisions that affect several trades.

For simpler renovations, close supervision by a reliable contractor may be enough. For more complex projects, however, regular involvement from the designer helps preserve the overall logic of the project and avoid a succession of improvised decisions.