Im going to make a bit of a punt on this one, mostly as I am keenly aware if things go before NCAT it “can” end up as an interpretation of the act made of the member of the day.
s108 I believe is intended for more substantial changes to common property, such as a retaining wall etc, whereas s110 is for minor changes as Jimmy has indicated. A screen that cannot be seen and presumably isn’t a more substantial modification would likely be covered by s110. I would therefore lean toward Jimmy’s argument because.
s110..
(8) Section 108 does not apply to minor renovations carried out in accordance with this section.