One floor of concrete plus five floors of wood is a common pattern, but it isn't necessary. You can easily build a six story building wood frame building. Also

One floor of concrete plus five floors of wood is a common pattern, but it isn't necessary. You can easily build a six story building wood frame building. Also, a big focus of urbanists is the "missing middle"[1]. This is the idea that there is too much focus on single family houses and high-rises and too little focus on housing that is shorter, but still denser than single family houses. [1] https://en.wikipedia.org/wiki/Missing_Middle_Housing https://en.wikipedia.org/wiki/Missing_Middle_Housing