Ask the Redland City Council
Addition to my answer above. at the end of the day you can try to get away with what you want, but you may just build it and either someone dobs you in (probably not) or RCC are watching google earth and see your build from space, they could come along and ask you to knock it down or ask you to get it certified and if not done properly you may not get approval and have to pull it down anyway. There are all sorts of council worker who come over to the islands to read meters, mow public spaces etc, you never know who may dob you in? Some have taken the risk!