oooo. i'm jumping as well & personally wouldn't be comfy w just a 5 story fall, esp onto an uneven & not completely clear surface. ppl have def died from that height & less, i just wouldn't want to risk any chance of survival w a method like jumping, & the higher the better.
i unfortunately had to settle for a 10 story parking garage :p but that should be more than enough to get the job done. i'm 5'5 & 100lb w a brittle bone disease on top of it, 100% gonna explode into viscera on impact, lol.