Yes — Islam legislates privacy inside the home, not only at its front door. Allah commands that servants and children who have not yet reached puberty seek permission at three times of privacy: before Fajr, at midday when garments are laid aside, and after ʿIshā'; and once children reach puberty they must seek permission at all times, just as adults do. The broader command not to enter houses until you have sought permission and greeted the people establishes the principle, and the Prophet ﷺ taught that permission is sought three times and if there is no reply you leave. Practically, this means knocking before entering a parent's, sibling's or grown child's room, and not reading their private correspondence — modesty and trust within the family are commanded, not optional courtesy.
Q&A · Family
Do family members need permission before entering each other's rooms?
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.