From my understanding too, there is no grandfather law, and I would purchase a place on it’s legal size and don’t include any furniture that is to be left behind too. One thing to look out for in rooftop or top floor apartments is the quality of the roof itself. In many typical five floor, old apartments, the cement and roof itself is of poor quality and will leak water or grow mould on the inner ceiling, shedding the paint from the roof and causing an annoying site. The addition of a rooftop apartment may hide some of these irregularities from the apartment below, so be on your guard. The rooftop law is something about there being no solid walls over about three feet tall, which is why our rooftop has been legally put up and even has gas mains and such. The problem is that the roof is iron and supporting the roof above the 3 feet high limited wall is nothing but windows…Bring on that 42 degree summer heat, which costs us 20,000nt in electricity in the summer to cool and almost as much to heat in the winter, though to no avail. Also windows don’t block out much sound at all, which is fine if you want to know every one’s gossip and hear about who is fighting with who in the dead of night. Rooftops are great for BBQs and parties though, and as long as you keep the noise down, the neighbors shouldn’t complain. They are noisy enough where I live to notice, so I am lucky.
I am told by a construction ‘expert’, a term to use loosely around these parts, that the best rooftops will last up to seven years of weathering before they start to leak and fall apart, after which time they almost always need replacing to be without faults, but don’t take my word for it. We have been in ours for about four years now, and although I love the space and balconies, it has to be the worst apartment I have ever lived in, with mould and faults galore, including flooding in typhoons, plus the expense and noise. Did I mention that it sounds like being in a base drum when it rains? You can turn our massive amp and stereo system up half volume, before you can hear the TV, and that’s loud, believe me. Oh, and this was a brand new, well built rooftop, so be warned.
Buy the place for the legal space and consider the quality of it. Forget about the additional rooftop, as it may not be worth the investment at all, and may even be torn down in the future, who knows?! Oh, and top floor apartments (not the rooftop, but the one below)are frequently on average about three degrees warmer than any lower apartment, which you should factor in to you electricity budget if you have one, as it will make a significant difference if you like the cool of your air con in the summer.