That is a hard situation, poor baby! Have you tried using a live trap? If not, maybe feeding him closer and closer to where you get up on the roof to the point where he can find the exit? Maybe a Half a Benadryl will make him sleepy, but I don't want to recommend doing it until you check with a vet, he might have a reaction to it. It is tough, but thank you for taking cate of him. Any neighbors that may take over while you are gone to feed him? I time the little thing will probably trust you enough to be picked up and taken safely off the roof, but you may need to work on that after you get back from vacation.