On the advice of a structural engineer I work with was told to put concrete in the hole first.
That way water will not wick up the lumber making it last much longer.
I also asked a friend with builds decks for a living he said that is the correct way.
Because water will not run down the inside of a post and pool at the bottom.
Leaving the post exposed to the ground under it keeps it wet all the time, it never ever dries and rots very quickly…
It's bad if you have dogs that dig. Lol. They will dig it up and tear it up and possibly ingest it. Biggest mess ever. Took a shop vac outside to get as much foam pieces up as possible. Very easy to use though.
