a 2.0 m high block capped rendered wall can be built without permission bounding any garden of a house, the max height you can build to the front is 1.2 m..... a metal palisade fence or security fence is not exempt.....the problem as i see it is the definition of 'house'... is an apartment block a 'house'.???.... i would argue that it is not... therefore, in my opinion, any new wall would require permission.....but to be sure, to be sure, contact your local authority and ask them....