No wood deck posts when I built mine. Everywhere a post would go I put in a concrete footing and used the cardboard round sleeve to have it above ground. Nothing in ground to rot. Used 8" by 4' sleeve but cut them into 1 foot pieces since it only takes a few inches above ground. I think I ended up with around 20 footings. There are under every joist under deck. The biggest pain is you have to take time to adjust them to the same level. The posts for railing are above ground and carriage bolted to the double 2' X 10' header, This deck is 25 years old.

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