Int 3-6 and sapience.[]
"Elementals, although not bright, are in the human level of intelligence at all sizes except (arguably) Small and Medium elementals, which share an intelligence score with griffins, and those aren't usually played as sapient."
- I'm pretty sure I can find a section saying that int 3 is enough for sapience in the core rulebooks, and comletely sure i can find multiple elsewhere.