Is it permissible for the muezzin's son to use the mosque's rooftop to build shacks for raising pigeons?

The mosque's roof has two scenarios:

1. If it is an endowment (waqf) like the mosque itself: It is not permissible to use it for anyone's benefit unless the endower explicitly stipulated that; because the endowment is designated for the purpose specified by the endower, and using it for purposes other than its designated ones, such as weddings or mourning ceremonies, is prohibited.

2. If the mosque's foundation is endowed but its roof is not: In this case, whoever wishes to use the roof must seek permission from its owner. If permission is granted, it is permissible; otherwise, it is considered trespassing on another's property.