Root seems to work fine for what I wanted to accomplish and I didn't have to create a new unit or anything. All i had to do was add height, speed, turn rate and change the movemnet mode to flying for a building (town hall in this case), and then give the building the root ability and it flew around and landed just like i wanted. There were only two problems.
1) Buildings that flew around after being "uprooted" would merge together in the air if ordered to move to the same spot.
2) The flying buildings are still targeted as ground units and are attacked by units that only have ground attacks.
I was wondering if there was a way to change what a unit is targeted as using triggers but I'm kinda a noob with triggers and stuff. I'll have to check it out but if anyone would know how to make a flying building targetable as air when its flying and then change it back to targetable as structure when it lands again, I would appreciate it if you would let me know.
Vgsatomi, as far as I can tell, the root\uproot ability doesn't leave you any option to replace the ground unit with another like the bear form ability does for example (normal form u8nit-alternate form unit), so I don't think the tergeting problem can be solved in that way. Thanks for suggesting that I use the root ability however. Despite the two minor flaws I think I'm still gonna use it.