Who can give approval for major internal lot renovations?

Our Strata Plan has 12 apartments and the Plan of Subdivision states “Interior Face: All Boundaries”.

One lot owner has started a major renovation which involves demolishing interior walls, demolishing the kitchen and bathroom and removing fixed wall and floor coverings (tiles and hardwood). So a fair bit of Common Property is involved (eg the floor coverings and fixtures on perimeter walls) and the lot is now almost an empty shell.   We also have a common fire sprinkler system in all the lots installed to AS2118 specifications.   The lot owner asked for permission by email to our OC Manager, who replied saying “Your lot is yours and you can do anything as long as it complies with Building Regulations”.

Does the OC Manager have authority to give such approval?  Or should the Manager have referred it to the Committee or to a general meeting?  I would imagine that the OC would want to ensure that the building’s structural integrity is maintained and that with any new room layout, the fire sprinklers are re-installed in accordance with AS2118 (as the safety of the whole building is affected).

At our AGM both the Manager and the Committee were delegated all OC powers and functions under Section 11 of the OC Act 2006 (Victoria).  This means everything other than a power or function that requires a Unanimous Resolution or a Special Resolution.

So is it the case that either the Manager or the Committee can give approval and that one need not inform the other of their decision (the Manager did not inform the Committee)?  And is an email exchange considered written approval?