I have an old fence with round metal post that are concreted in and in good condition but I want to replace them with timber posts. To avoid digging everything up I would like to cut the metal post down to about 150mm and drill out the post to slide over it and bolt through.

My question is, if I need to drill 50mm hole 150mm vertically into the middle of the post is a 100x100mm post big enough to still maintain enough strength? - I can go 150x150mm it just might look a too over sized for the area the fence is in.

  • How tall are the fence posts? If they are 1.5m then a fixing of 150mm will mean they wobble and with wood v metal that will just get worse over time.
    – Solar Mike
    Commented Sep 4, 2019 at 4:47
  • 3
    I would STRONGLY suggest "wrapping them with boards" ( not cutting them down at all) for a "timber look" rather than what you propose.
    – Ecnerwal
    Commented Sep 4, 2019 at 12:40
  • 1
    Agreed wrapping will provide strength and not split out at bottom when the wind blows it over +
    – Ed Beal
    Commented Sep 4, 2019 at 14:08

1 Answer 1


(Sorry I'm not Metric, we use 2x material) Dado out a wooden Post for the pole, then add a 2x to the side you dadoed out to cover it and screw it to the dadoed post and bolt the whole thing together

Depending on the Diameter of the post, you can also wrap it in 2x. We have also done 2x6 Left to right (So you see the 2x6 face on the fence, I like 4x6 Fence Posts. Then between them, also flush against the post, cut a 2x to fit between the 2x6 and bolt though the side 2x4s.

Sizing might be off, but I think you can get what I'm describing? We use Carriage bolts on the side you see and counter sink the nuts.

Pipe Wrapped in wood

  • 2
    You should consider doing a diagram for clarity...
    – Solar Mike
    Commented Sep 4, 2019 at 9:16
  • Much better than op idea of cutting off. I understand but agree with mike, some may need a drawing and that would definitely get my up vote.
    – Ed Beal
    Commented Sep 4, 2019 at 14:07

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