1. Lotus root means "Passepartout" because it has long strips outside and air traffic control inside. It means good luck. Generally speaking, take the meaning and the meaning of shun.
As for planting lotus roots on the roof, "clearing the way at the top" means reaching the sky. Unless this family is mainly involved in the central government or the cultivation of immortals and buddhas, I really don't know what the significance is.
As far as I know, there is only one exception, that is, in some areas in the south of the Yangtze River, people set up "roof farms" on the roofs, which is out of the need of diet.
Conclusion: There is no well-founded theory for planting lotus root on the roof.