so i was on top of simons turret, and i tossed 2 sticky nades down using secondary fire (roll) and they bounced off, so then i threw one instead and it stuck to the turret, it hit the exact same spot as the ones i rolled (I was throwing straight down) i havent tested this on bigger buildings yet, but i cant see why it would make any sense for sticky nades not to stick because you use secondary fire? ;o and also here's a big rant unrelated to everything above: stickies irl usually have a covering, i dont think this should be added yet but in the future i think stickies should work differently, before you throw stickies you'd have to take off the cover, and after the cover is taken off the stickies could accidentally stick to yourself, teammates, tanks, etc if you touch the object with the sticky. to arm the sticky after taking off the cover you'd have to pull a pin that makes the sticky blow after 5 s, and then of course u could throw it : o woot woot (big rant end)
i would imagine that rolling represents not activating the adhesive. after all you dont want the nade to stick to the blade of grass by your foot.
