an architect does not necessarily design buildings or houses from bare ground. He can intervene on the existing whether we are dealing with renovation or rehabilitation issues. Renovation includes all finishing work on a building already in operation or left unfinished. This involves rethinking the appearance of the building by bringing the style sought by the client through shapes, types of materials and colors of which the architect has the secret. This renovation operation also makes it possible to resolve any latent functional problems. These could be windows that are too exposed to afternoon sun or rain. It could also be a room that is poorly lit or poorly positioned in relation to the overall functioning of the building, etc.

Rehabilitation has a historical and even cultural connotation. The aim here is to restore the building to its former glory while respecting the original project almost to the letter. This process is a science which involves, in addition to the architect, several other experts, notably in historiography, in ancient or specific construction techniques and is very often intended for buildings which are part of the historical and cultural heritage of a community.