Short answer. An ordinary repair is one required by the wear and tear from the thing's natural use, and that is indispensable for its preservation — the everyday upkeep a usufructuary personally must shoulder, distinct from major structural work that falls entirely outside this narrower legal definition.
What the law says
By ordinary repairs are understood such as are required by the wear and tear due to the natural use of the thing and are indispensable for its preservation.
Civil Code, Article 592 — Ordinary Repairs Are the Usufructuary's. Read the full provision →
The two-part test Article 592 sets
Article 592 does not leave "ordinary repair" undefined — it gives a specific test with two elements that both need to be present. First, the repair must be needed because of wear and tear due to the natural use of the thing — the ordinary deterioration that comes from using the property the way it is meant to be used, not from an unusual event or a defect that existed from the start. Second, the repair must be indispensable for the thing's preservation — meaning skipping it would let the property actually deteriorate further, not merely make it less convenient or attractive.
Why this is a narrower category than repairs in general
Because both elements of the test have to be satisfied, "ordinary repair" is a narrower category than every repair the property might ever need. A repair caused by an extraordinary event, a structural defect unrelated to normal use, or a repair that is merely desirable rather than indispensable for preservation does not fit this definition, even if it is still, in a general sense, a "repair." The article is specifically distinguishing the everyday maintenance a usufructuary is expected to absorb from the article does not describe major structural work.
What happens if the usufructuary does not make the repair
The article also sets out a consequence for failing to act. If the usufructuary does not make the ordinary repairs the property needs, the owner may, after demand, make them instead — but at the usufructuary's expense. This demand requirement matters: the owner cannot simply step in and do the repair and then bill the usufructuary without first having asked the usufructuary to handle it. Once that demand has been made and ignored, though, the owner is entitled to recover the cost from the usufructuary.
What the article leaves to the owner
Article 592 binds the usufructuary specifically to ordinary repairs — it does not, by its own terms, say who bears the cost of extraordinary or structural repairs that fall outside this two-part test. Where a repair does not fit the wear-and-tear-plus-indispensable-for-preservation definition, this article simply has nothing to say about it, leaving that separate cost question to whatever other rule governs extraordinary repairs. That gap is itself useful to a usufructuary trying to figure out whether a particular expense is theirs to bear under this specific provision, or someone else's responsibility instead.