Who owns a structure built upon another person's wall?

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The structure, such as a built wall, supporting beam, or dome resting upon another's property, belongs to the builder. This view is held by Al-Shafi'i. The reasoning is that placing one's structure upon another's property establishes a form of possession by utilization, similar to loading goods onto an animal or sowing seeds in land. Furthermore, it is presumed that a person would not normally allow another to build upon their wall. If there is a beam originating within one person's property but extending under a wall exclusively belonging to the other, or if there is a beam resting on it, the disputed wall belongs to the person whose structure utilizes that beam, as it is presumed the structure built upon the beam also belongs to them.