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I have a 6 foot wooden privacy fence I am looking to replace. Several of the posts are rotting right at ground level so their concrete footings are going to have to go.

A company sells a metal fencepost that is meant to be hidden and present the appearance of a wooden fence, which is desirable to me. I am thinking of using them as the metal should outlast any wood.

Rather than installing new concrete footings, I see a popular and cost effective method of installing fenceposts nowadays is with a vibratory driver that hammers the fenceposts right into the ground. Since I'll likely use a skid-steer to rip the old footings out, I can get an attachment that can drive in replacement posts. Put 4+ feet of post in the ground and 6' above and the fence should be solid.

The only question is how to prepare the soil. Ripping out the footings is going to leave holes that need to be filled. What steps should I take to compact or stabilize the soil, so that it can properly hold the posts? Would a plate compactor or jumping jack compactor be a good idea, or something else?

Or, should I just abandon this idea altogether and pour new footings for the new posts?

I live in Minnesota, with serious winters, and pretty loamy easily drained soil, so whatever I do it needs to withstand frost heave. Some of the current posts are not doing well at that.

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  • Wow! Four feet in the ground! Maybe that is what is needed in MN. What is this fence going to hold, a 2000-lb Holstein bull? (What company sells these posts and how much are they?)
    – Jim Stewart
    May 1, 2018 at 22:07
  • @JimStewart: I don't know if that's totally necessary, but I've always seen the 2:1 rule, so going 4 feet to be on the safe side seems like "might as well" to me, especially if I use a machine to install them. Build once ache once. This is for a city yard so no crazy bulls :) The posts are Master Halco postmasters, I've seen them in 10' lengths. I don't remember how much they cost but it was less than double a comparable PT 4x4.
    – whatsisname
    May 1, 2018 at 22:13
  • I second what Jim said - 4 feet is a good bit excessive. I would personally do something like 16-24 inches for a home fence.
    – cutrightjm
    May 2, 2018 at 2:12
  • @cutrightjm: ok, well, regardless what the ideal depth is, that's not the point of the question, how to prepare the soil is.
    – whatsisname
    May 2, 2018 at 3:41
  • In Dallas TX 8 ft long 4 x 4" pressure treated posts are adequate for a 6 ft fence. Thirty-five years ago when I replaced some of the original 4 x 4" cedar posts (termite eaten, rotted) with pressure treated I used a heavy digging bar and a standard hand post hole digger to clean out the holes, put soil in and tamped manually with the tamping pad of a heavy metal bar. That is, no concrete. But here we have soft limestone 18" below grade in some places. This is the so called Austin Chalk. I would be interested in seeing if this vibratory pile driver could drive fence posts through that.
    – Jim Stewart
    May 2, 2018 at 7:57

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Cut off old posts slightly below grade.

Leave concrete footing in place. Drive in new posts 4feet deep into ground at a short distance to the left or right of old post. Driving in that deep would mean no footing necessary. Leaving the old post base and concrete would eliminate need to compact. Enjoy your new fence. Thanks for asking here because now I know about these posts and will use them on my fence redo.

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