Maybe that helps too, as there are more edges close to the borders the more you subdivide it.
But as you said it is not a solution cause you need to subdivide a lot, and still have some angles (small but noticable). Chamfer worked for me the best, just mind the corners not to have something huge displaced, like in your case balconies if I'm not wrong. It may seem weird results, but again I can not say how it should be and don't know how a better solution would be.