Definition : Building envelope

All the walls of a building that separates the interior volume of a building from its external environment and whose function is to protect the interior from bad weather.  Generally, the building envelope consists of the roof, walls, windows and doors, that is, everything that separates the interior of the building from the outside. In a vertical co-ownership,  the building envelope constitutes a common portion of the building. However, the situation differs  in horizontal co-ownerships, where the building envelope is generally located in the private portions.