correct relative pronoun

What is the correct relative pronoun (I believe this is the correct term) for a sentence like: The house _____roof is on fire is my best friend’s. If the subject of the sentence were a person I know it would be “whose”, but it seems strange to use this word with “house”

thanks in advance for your help

Hi Jenniesue

The word ‘whose’ is used to refer to both animate and inanimate nouns.
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