Is it permissible for a man to reside on a rooftop adjacent to his divorced wife's house, after their irrevocable major divorce, in order to care for his children?

If the dwelling is separate with its facilities from the divorced woman's dwelling, then there is no harm for the divorcing man to reside in it. The irrevocably divorced woman may observe her iddah wherever she wishes in her country, in a safe place. She should not travel or spend the night except in her home. If the divorcing man's house is spacious enough for both of them, and she can reside in a separate place, such as an independent room with a lockable door, while the husband resides in the rest, then that is permissible.