Not only are the Brazzaville houses different from the Niamey one (cf. comments details of Niamey photos), they also differ from each other.
The smaller house (14 X 10 m) designed for offices originally had a wraparound balustrade in tubes later replaced by modern railing.
The bigger house (18 X 10 m) designed for dwelling was originally equipped with aluminum sheet railings, still in place, to preserve the privacy of the occupants. These superb aluminum shells with cutout ventilation grooves are reminiscent of the hoods of racecars from the 60s. The inner side is painted in the same blue as the pillars; the external side is in untreated aluminum.
Curiously, the railings are mounted on hinges allowing them to swing forward. This dangerous function, four meters above the ground, had been disabled. There has been lots of speculation over the utility of this system, was it to facilitate the cleaning of the verandas?