Author Topic: Replacing a timber fence post  (Read 42015 times)

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  • The Plantsman
Replacing a timber fence post
« on: July 15, 2013, 08:58:19 am »
Even after buying a brand new home, the chances are that after a few years you will have to replace a broken fence post. This is not as difficult as it seems; the hardest part is removing the old post and concrete. Thankfully fencing contractors use a weak dry mix concrete that can be broken out by hand using a 25mm cold chisel and 1lb club hammer.

It is a good idea to paint two coats of bitumen paint on the new fence post starting around 400mm below ground level (leaving the bottom 200mm unpainted) and extending to 150mm above ground level.  This helps prevent the post prematurely rotting just above ground level in much the same way as the more expensive alternative 'Postsaver' sleeves do.

Posts should be set 600mm into the ground.  With an 1800mm high fence you will need a 2400mm long post.  Timber fence posts should always be treated timber. The concrete mix for fence posts can be weak around 1 part cement to 5 parts 20mm ballast.  Usually, you will need a bag of ballast per post. Mix the concrete up when dry and add just enough water to bind it together – about a half a pint per bucket of mix.

The bottom of the post should be in contact with the bottom of the hole. Or if you have gone too deep, back fill the hole to the right level with ballast or shingle. This allows water in the post to drain away rather than accumulate at the bottom causing the post to rot. Never concrete under the fence post!

Fix the post to one panel keeping it parallel with the panel (use a piece of timber as a spacer). Then make sure the post is in line with the fence line using a stringline just above ground level along the fence and then ensure the post is vertical/plumb using a spirit level.  When you are happy you can add the concrete mix a little at a time, firming down around the post in layers. Keeping checking for line and plumb after adding each section of concrete. Concrete up to 150 below ground level. This allows for 150mm of topsoil over for plants or grass. It is a good practice to slope the surface of the concrete away from the post so water can drain away.

Fix the other panel to the post and