Indeed, some jumping required, but you can get to the rooftop well enough.  Opening the door is easy, and thankfully you catch it and slow it down before it creaks.  Inside it's a short stairwell down to the second floor, which is bare and shoddy as anything else.  There's another starewell nearby leading down - you remember it from before and it lets out near the door you entered.  You can hear voices in conversation, both of which you recognize, though it's hard to tell what they're saying.  If you look down the stairway, you can see the door is shut, and you don't see anybody yet...