Between France, Belgium, and Luxembourg, laws relating to installing smoke detectors differ greatly.
In Belgium, these systems are required throughout the country, but the conditions differ depending on the region:
In the Brussels region, installing smoke detectors has been compulsory since July 1, 2005. But this does not include housing for rent, for which installation is the owner or lessor's responsibility. One condition specifies that a detector needs to be installed in every room that needs to be walked through to get to a bedroom from the door leading outside.
In Wallonia, the obligation to install detectors dates back to July 1, 2006. Residences under 80 m² need to have 1, and for larger residences, at least 2 are required. If the residence has multiple floors, the same rule applies to each floor in terms of surface area and the number of devices. If the residence has more than 4 detectors, they need to be interconnected via a centralized detection tool.
In Flanders, not all types of homes are yet affected by the obligation. The law only applies to new residences, renovated residences, residences purchased with a social loan as of January 1, 2013, and most rented homes (namely social housing, student dorms, and private rented homes built before 1945). Like in Wallonia, a detector needs to be installed on each floor of the home. And for buildings that have student dorms, a detector needs to be installed in each one. In Flanders, private rented homes that are rented as the main residence and that have been built after 1945 must be equipped starting January 1, 2019. And starting in 2020, smoke detectors will be required in every residence.
In France, putting in smoke detectors has been compulsory since January 1, 2016. All residences are affected, whether they are the main or secondary residence, a jointly or individually owned building, or whether or not the home is occupied. At least 1 detector is required per residence, but 1 is required per floor if it is a house or duplex. For rentals, installation costs are the responsibility of the owner.
Finally, in Luxembourg, equipping smoke detectors will be compulsory starting January 1, 2019. They'll need to be installed in every new home. But an additional 5-year grace period will be granted for existing residences.