Questions & Answers about Pihalla on vanha vaja.
If we changed this to "There is an old shed in his yard", could we drop the pronoun hänen and just say Pihallaan on vanha vaja?
No, you would have to say Hänen pihallaan on vanha vaja. The rule for omitting hänen or heidän only applies when the owner is the grammatical subject of the sentence (e.g., Hän rakentaa vajan pihalleen - "He builds a shed in his own yard"). In our existential sentence, the subject is vaja (the shed), not the owner, so the pronoun hänen is mandatory.
Why does the sentence start with the location (pihalla) instead of the subject (vanha vaja)?
This is an existential sentence, which introduces something new to a location (equivalent to "There is..." in English). In Finnish, starting with the location and putting the subject at the end signals that the subject is indefinite ("an old shed"). If we swapped the order to Vanha vaja on pihalla, the meaning changes to "The old shed is in the yard."
English says "in the yard", so why does Finnish use the adessive case pihalla (on the yard) instead of the inessive pihassa?
In Finnish, outdoor spaces that act as open surfaces or areas attached to a building (like yards, market squares, or streets) typically take the adessive case (-lla/-llä). While the inessive pihassa is sometimes heard in dialects or specific contexts (like being deep inside a bushy garden), pihalla is the standard, natural way to express being in a yard.