Sleeve Fence Posts at the Ground Line Before Setting Them

The Problem

Fence posts almost never rot at the bottom of the hole. They fail in the band a few inches above and below grade, where the wood gets the full wet-dry cycle plus the oxygen fungus needs. Concrete doesn't prevent it — water tracks down the post-concrete joint and sits right in that zone.

The Technique

Ground-line barrier sleeves (Postsaver is the common brand) attack exactly that band:

1. Slide the sleeve onto the post before setting it.
2. Position it to span the ground line — part of the sleeve ends up buried, part sits proud of grade, covering the whole decay zone.
3. Heat the sleeve with a torch or heat gun until it shrinks tight and the bitumen liner melts and bonds to the wood, sealing out water and soil contact.
4. Set the post as usual, sleeve and all.

The rest of the post survives fine on its own: fully buried wood is too oxygen-starved to rot quickly, and the exposed section above dries after every rain. Sealing the transition zone is what adds years.