Guidance on the ATC separation of other aircraft from the wake of the A-380 can be as little as 5 miles to as much as 10 miles according to multiple variable factors. It appears that the required separation for aircraft flying behind "Super" heavies averages 30-40 percent greater than for "Heavy" aircraft. It won't surprise me a bit if 748s are declared to be "Super" or "J" class as well.