Which is the correct level?

[mineko]

Once a building is above a certain level, we use the largest opening in the house.

What level should it be. I have read some saying above 7th storey. And some saying above 9th storey. Which is the accurate one?

[Vonduos]

Once a building is above a certain level, we use the largest opening in the house.

What level should it be. I have read some saying above 7th storey. And some saying above 9th storey. Which is the accurate one?

Nope it will stay depend on your qi mouth is.
Even if you stay in 99th storey, if your house have no balcony or other opening, your qi mouth will still be determine by your main door.

not neccesary the largest opening in the house.