All of the structural components of the building: It includes every component insuring the strength and stability of the building, more particularly, the foundations, load bearing walls, floors, posts, beams, etc. These components are all together part of a system; thus the alteration of one or many of them may alter the whole structure. The Civil Code of Québec creates a presumption to the effect that they are a common portion of the immovable.This is generally the case in vertical co-ownerships. The situation is different in horizontal co-ownerships were the foundations and main walls are generally situated in private portions.
The characteristic of divided co-ownership is to divide the building into various lots that will be the exclusive property of the co-owners (private portions), and for others that will be the property of all the co-owners (common portions). These lots are identified by an individual number, which was assigned during the cadastral operation. Each of the private lots of the co-ownership thus constituted becomes a unique property. The distinction between the common and private portions is essential, particularly from the point of view of maintenance, which is the responsibility of the syndicate of co-owners for the common portions and of the co-owners for the private portions.