He—may Allah have mercy on him—was asked:

What is the ruling concerning a man who owns a house, with a road separating the neighbours’ properties, and has an overhead structure spanning the road and resting on one of their properties, without harming either the neighbour or passers-by, when another neighbour wishes to project out equally far and extend beyond his neighbours [into] (1) the road, causing harm to his neighbour?

He answered:

An overhead structure of this kind, or anything similar, is impermissible if it causes harm, by agreement of the scholars. Likewise, no one may extend any part of a building into a road used by Muslims. Indeed, even plastering the outside of a wall is prohibited unless the wall is set back by the thickness of the plaster.

If, however, such an overhead structure or the like does not interfere with the use of the road, there is a well-known disagreement among the scholars. Some hold that it is permissible, as al-Shāfiʿī maintains. Others hold that it is impermissible, as in one of the two views within the schools of Ahmad and Mālik. Others hold that it is permissible with the ruler’s permission, according to the latter view. Still others hold that if any member of the public objects, it must not be built; this is the position of Abū Hanīfa. And Allah knows best.