The property has today only one floor (ground floor). It seem to be possible (based on decision and conditions from the town hall that the Buyer is responsible for) to extend the building with another two floors (same as the neighbours have done) and have a roof terrace.
By looking at the neigbourhood you can see what could be possible. Of course it's the town hall that decide and give permissions, but with contacts taken 2019/2020 it only seem to be a formality and how the extension will look like, to get it approved.
Just around the corner (Calle Extramadura) you can find a project with a similar plot, and how they have develop the property (no roof terrace though). 3 floors of living area. See photos below.
In 2019 the present owner made a presentation of the different options, in order to either keep the property as it is, OR to develop with more floor. See the presentation below.