Any renovation rules for older buildings?

For those living in older buildings (~50 yrs), generally the walls are non-load bearing and can be more easily moved, although there are structural beams that must stay in place, obviously.


Can anyone advise what (if any) rules apply for:

1) balconies? I have seen many that have been bricked up and rooms enlarged: is this legal or will someone one day ask you to restore this?


2) windows? Since these will be replaced, and I have seen some bldgs with windows that have been enlarged quite a bit, again, are there rules governing this?


Anyone with experience in this area? When I ask the agent, they tell me that anything is possible, but I'd like to know if I need to seek the advice of a qualified engineer or contractor beforehand.


thanks in advance for advice

I'm especially curious about the older bldgs that have probably been like this for decades. If the agent asks for such acknowledgement, is it also correct then that I can also ask for proof whether these changes are legal? (of course if there is none, there probably isn't much that can be done..)

I'm thinking of a ~50 yr old bldg, not sure if that is pre-war or not.... If there are no records, what's the procedure in that case? thanks for your input, really appreciate it