Short answer. Yes, unless you agreed otherwise. Article 669 allows you to make small, grated light openings in a wall you own solely, but if your neighbor later acquires part-ownership of that wall, he may close those openings — provided there is no stipulation to the contrary and you have not acquired a formal easement of light.
What the law says
the owner of the tenement or property adjoining the wall in which the openings are made can close them should he acquire part-ownership thereof, if there be no stipulation to the contrary. He can also obstruct them by constructing a building on his land or by raising a wall thereon contiguous to that having such openings, unless an easement of light has been acquired.
Civil Code, Article 669 — Restricted Openings For Light. Read the full provision →
When restricted light openings are allowed
Article 669 permits the owner of a wall that is not a party wall to make small openings for light — up to thirty centimeters square, set at ceiling height, fitted with iron grating and wire screen. These are restricted openings, not windows. They are allowed precisely because they are at the distance violations described in Article 670 — the minimum distances for direct views over a neighbor's land are not observed. The restrictions on size and placement are meant to limit how much light passes without giving a real view into adjacent property.
What happens if your neighbor acquires the wall
The right to keep those openings is fragile. Article 669 makes clear: the owner of the tenement or property adjoining the wall in which the openings are made can close them should he acquire part-ownership thereof, if there be no stipulation to the contrary. Once your neighbor becomes a co-owner of the wall, his ownership interest gives him the right to eliminate the openings, unless you and he agreed in writing that they would remain. The burden is on you to have protected the openings contractually before co-ownership arose.
He can also block them without acquiring the wall
Even if your neighbor never becomes a co-owner of the wall, the law gives him another route: he can construct a building on his own land or raise a wall along his boundary that blocks your light openings entirely — unless an easement of light has been acquired. This means the openings give you no permanent right to light. They are tolerance, not title.
How to protect your access to light
The only protection that survives a neighbor acquiring the wall or building against it is a formal easement of light. This is a voluntary easement that must be agreed upon and — to bind third parties — registered. A written stipulation at the time the openings are made, agreed to by your neighbor and noted in the title records, gives your openings legal standing against future co-owners and builders. Without that, the openings are a privilege the neighbor can extinguish when the legal conditions arise.