To level the sloping alcove floor, the Ancestral Puebloans filled in behind retaining walls. The altered floor not only supported rooms but also provided working space and a safe play area for children. Oak Tree House appears to utilize every inch of alcove space. Some apartments rose 4 stories to the roof of the inner alcove. There are additional storage rooms along an upper ledge. The dwelling contains about 50 rooms and 6 kivas.