Not just underwear, anything thing such as cloth or any other laundry items are not allowed to hang in Balcony of your apartment. I received notice not long ago after I move in. :)
Why I say only underwear? Because I've been told before only underwear is not allowed. So it is not just underwear, you basically can't hang "anything" in balcony. You're supposed to use dryer to make your cloth dry!
I look into the the strata title law in detail and this is what it says:
This should be applicable to all apartment in Australia. Yes, you're not allowed to do that unless you get the formal approval. The last sentence is confusing but I guess it only applies to apartment that have common property clothes lines but "reasonable time' is a funny statement. Maybe not more than 24 hours?
So one of the drawbacks of living in strata title property in Australia is you can't simply hung stuff in your balcony! :)
P/S: Weird thing is I still see most my neighbors are hanging their clothes in balcony. Is this rule not really enforced here?