本来なければ usage and meaning


> 屋敷を一回りしただけで設計図を思い描き、 **本来なければおかしい部屋がない事を指摘する。**

What does the last sentence mean?

> Just by going around the mansion once he was able to drew a blueprint, **If
> it were not normal it points out the fact that there are no strange rooms?**

本来ならば=Normally  
本来なければ=Not normally ?

I am really not understanding that.  
Thank you




You would parse it as:

> [(本来、なければおかしい)部屋がない]事を指摘する。

本来なければおかしい is a relative clause modifying the 部屋.

なければおかしい部屋 means なければならない部屋 / あるはずの部屋 / あるべき部屋, "a room which should exist,"
"a room which should be there."

So your sentence would be like:

> (lit.) He points out that [a room (which naturally should exist) doesn't
> exist].  
>  He points out that [a room (which naturally there should be) isn't there].  
>  He points out that [a room (which originally should be there) is missing].




You would parse it as:

> [(本来、なければおかしい)部屋がない]事を指摘する。

本来なければおかしい is a relative clause modifying the 部屋.

なければおかしい部屋 means なければならない部屋 / あるはずの部屋 / あるべき部屋, "a room which should exist,"
"a room which should be there."

So your sentence would be like:

> (lit.) He points out that [a room (which naturally should exist) doesn't
> exist].  
>  He points out that [a room (which naturally there should be) isn't there].  
>  He points out that [a room (which originally should be there) is missing].

