If the owner of the upper floor refuses to rebuild the lower walls demanded by the lower floor owner, is the upper owner compelled or assisted?

Primary text

There are two narrations concerning the obligation when the owner of the lower floor demands reconstruction, and the upper floor owner refuses. According to one narration, he is neither compelled to build nor to assist in the building. This is the position of Al-Shafi'i, as the wall is the exclusive property of the lower owner, and thus no one else can be compelled to build or assist, just as if there were no upper structure.