To be given exclusive use of common property a bylaw has to be passed with 75% of votes cast in favor of the motion and then this bylaw has to be registered with the state gov.
It might be an idea to have a word with the guy to advise him that he is altering common property and so far what he has done maintains the look of the property but if he does something out of keeping the EC is able to restore it to it’s original condition and bill him the cost and so it might be an idea to run any changes past the EC before doing them.
Because he is maintaining it he is saying the EC money and so you have to be careful otherwise he might stop doing it and leave it to the EC to maintain.