Does the roof or the 20 percent of the land become the property of the heirs and its price must be paid, or does it belong to the inquirer, religiously speaking, due to the father's consent to building on it with his full satisfaction?

The ruling depends on what transpired between the questioner and his father: Was it a gift (hiba) or a loan (ariya)? A mere permission from the father to build, without explicitly stating it as a gift, does not make it a valid gift. Rather, it would be a loan (ariya) that terminates upon the father's death, and the son would be entitled to the standing value of his building costs.

Unless the gift (hiba) actually occurred, ownership of the roof and the land remains with the father, and the right of inheritance is established therein for all heirs. Registering the house officially in the son's name does not constitute an explicit gift of part of the land.

It is recommended to revoke a gift if the father singled out one of his children with it and did not give the others similar, and some scholars deem it obligatory.