After working really hard to remove old concrete in far too many fencepost holes, I’ve concluded that setting fence posts in concrete might be a bad idea for urban fences. Unless you do the concrete right (extending above ground and sloping away from the wood-concrete contact), it doesn’t prevent/delay rot and makes replacement a real bear. For this application, we certainly don’t need the extra strength (no livestock!) and if we don’t stick around long enough for it to be an issue for us at replacement time, it’s very likely to be an issue for the next owners. Since we might still be around when these posts rot out, it perhaps would have been better to do the concrete, it would be in the way in our flower beds and some other places where space is tight. I’ve experimented with an old-time approach of charring the ends of (some) posts where there’s ground contact. I’m guessing that more than a surface char (I did it with a propane torch) is best, but even that might help keep rot at bay. The fact that I’m using redwood (mostly reclaimed) should help somewhat.

The one place I’m definitely using concrete is for our arbor column bases. Fence posts will be easier to replace than arbor columns with grape vines wrapped around them.

Why the replacement? Rot, rot and more rot.

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