Ok, currently this is not possible since the rop to climb onto it is hollow, but hopefully it will be made solid in a patch or something idn. Here it is:
1. Get to here.
2. Jump up to here.
3. Jump off to the other building here.
4. Run up the wooden beam and jump onto the higher ledge, ( may take a few attempts) then jump on the roof.
Final Pic
There you go may be hard at first.