chai – If this matter went to Adjudication the Adjudicator would look to see if other by-laws were in place to restrict what an owner or occupier was permitted to do to change the external appearance of a lot.
You have listed another by-law that relates to the external appearance of a lot therefore this could be construed as indicating that the uniformity of the external appearance of a lot is something that the OC has a particular interest in preserving.
The word “external” is not to be taken in isolation, instead it forms part of the phrase “external appearance of a lot”.
The OC has a duty to enforce the by-laws. If there has been a breach in a by-law then the OC can request that the owner remedy the breach.
You have three options: remedy the breach as requested by the OC; take this matter to a General Meeting and have the OC decide to allow the flooring change; or take this to VCAT.