this is correct but we almost never say that. Because if you are asking about "which floor", you must have known "which building does he live in". In this case, we just say: 你住几楼。

你住几楼？ 你在哪层（住）？

You could say "你住几楼" 日本語では　あなたの家何階ですか？ 英文的话 就是"Which floor are you in?"

Too complicate, just say "你住几楼？" is enough.

I can totaly understand what you say, so I think you can say that. XD