1. The house whose roof we see is my uncle's
2. The house the roof of which we see is my uncle's.
3. The house, roof of which we see is my uncle's.
I wonder which one is grammatical between 2 and 3.
If anyone is wondering, #1 is fine with a full stop.
I have no trouble using "whose" for an inanimate object. I certainly find #1 more natural than #2.
You could also say "The house we can see the roof of is..." but it's more awkward to me than the "whose" version.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.