@daveL said:
My understanding is that the body corporate cannot install work like this in the airspace of the lot, given that it is the property of the lot. Am I correct?
I’d be interested to see where you have read that as I’m not sure it’s true. For instance, the automatic door closure on the inside of your front door is attached to common property by intrudes into lot air space.
in any case, if the balcony is common property then so is the air space above it.