In the tall apartment buildings, on the 2nd from the top floor, you are able to vault into the next floor up, into an inaccessible room. You can vault when standing on players, or other items such as tent or a platform. Once in the inaccessible room, players can leave items or other wise be located in an inaccessible location.

You should not be able to vault through the ceiling. This area is not intended to be accessed.

See video for example: https://www.youtube.com/watch?v=gmIkzkIKVuU