Balconies are usually the property of the lot owner (on the strata plan there is a little “s” symbol that links the balcony with the rest of the lot). But the lot is basically the volume inside the lot boundaries. So the floor slab, the roof slab and the boundary walls are common property. The boundary wall between the balcony and the rest of the lot is also common property (except with older strata plans), because it is shown as a thick line on the strata plan. The boundary walls of the balcony are common property, which includes the balustrade.
Also, strata law protects the “look” of the building from outside, so an awning may not be allowed because of that principle. An owner will affix an awning to the common property exterior walls, so they will need to owners corporations approval to install the awning, even if the OC allows awnings to be added to the building, because they do not detract from the building’s appearance.