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.