I’m hoping to extend the height of my current 4x4x6 fence post on four corners of my yard so that I can attach triangular sail shades to them. I cannot remove the current posts with longer ones nor can I attach attach additional timber to them i.e. cutting and notching a 4x6 and bolting them to the existing 4x4. The additional height I need is about 6’. I thought about attaching a metal rebar type with holes in it and nailing it to the 4x4 post along with c clamps but worry about the wind and stress on the metal rod. What options do I have? Thank you.

  • how much overlap were you planning
    – Traveler
    Aug 9, 2022 at 8:03
  • You can buy post extenders in most garden centres. Wouldn't they do?
    – Chenmunka
    Aug 9, 2022 at 8:04
  • 7
    If you'd like to have the posts survive wind events, you probably don't extend the present posts and then attach a device that will increase wind pressure to them. So if you can't remove, dig a deeper hole, replace with a much longer post set much deeper in the ground - fuggedaboudit.
    – Ecnerwal
    Aug 9, 2022 at 11:17
  • 7
    The post foundations need to be designed for the forces that sails will place on them. They really need to be "sail posts" that for some reason only had fence attached to them initially. If not, you should leave the fence alone, and plan a different way to support the sails. Just plant new posts alongside the existing ones, just for the sails.
    – jay613
    Aug 9, 2022 at 12:36

1 Answer 1


Get some 8' sections of unistrut channel and bolt them to the sides of your posts with a few 1/2" bolts, washers and nuts.

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Picture from Granger

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