Concrete Fence Post Replacement

[odgeuk]

I need to reinstate my rear garden fence. The original appears to have been done with concrete posts, six feet apart, and then a couple of courses of bricks between them, acting like a gravel board. It was probably a nice job back in the day but the concrete posts have blown and mostly collapsed, from the rusting-out of the steels inside them.

In an ideal world, I’d somehow dig out the remnants of the posts and slip in some new ones, without destroying the wall in the process, however I’m concerned that I won’t be able to get enough new concrete around the new posts, if they are replaced in-situ. What's the approach here? (other than just building a new fence on the other side of the brick coarse!

 

[odgeuk]

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[JohnD]

It's difficult to dig out the concrete round old posts. Because it has been underground in damp soil for many years, it will be thoroughly cured and stronger and harder than usual, and very heavy. The typical workaround is to dig between the old posts and set new. If you can lay your hands on a breaker or heavy SDS+ drill you can break it into manageable pieces.

Consider yourself lucky if you are able to save any of the brickwork.

BTW the failure of your old posts, unless they were cracked, is probably due to excessive wetness causing the steel to rust. You can keep the rain out by treating your new posts all over with masonry paint, preferably before setting, but yours seem to be in wet ground. Is there a drain or gutterpipe nearby?

 

[JohnD]

It is possible to set the posts further forward, if you put concrete spurs in the ground, and bolt wooden posts (not touching the ground ) to the face of them. You can gain a bit more by putting a short spacer post between the spur and the post. You can gain a bit more by running horizontal boards (I use decking boards) to the face of the posts, or fixing beams to the posts and hanging fence panels on the front of the beams. Ready-made fence panels are very flimsy.

 

[aveatry]

The typical workaround is to dig between the old posts and set new. If you can lay your hands on a breaker or heavy SDS+ drill you can break it into manageable pieces.

Its taken me years as I have found them to remove old post concrete were the past two owners have done exactly that and just moved along which has resulted in the planted border being almost all concrete when ever i need to dig down to plant something. So you may well try along a littl bit and hit an old one again. I would take it out.

 

[JohnD]

It's bit easier to get them out if the post is still attached. Once you have dug round the concrete, the post gives you a lever to loosen it and possibly lift it out.

Now I have an SDS+ chisel I use that.

I have also resolved never to put wooden posts in the ground.

 

[odgeuk]

It is possible to set the posts further forward, if you put concrete spurs in the ground, and bolt wooden posts (not touching the ground ) to the face of them. You can gain a bit more by putting a short spacer post between the spur and the post. You can gain a bit more by running horizontal boards (I use decking boards) to the face of the posts, or fixing beams to the posts and hanging fence panels on the front of the beams. Ready-made fence panels are very flimsy.

I did consider this but figured I’d still have some issues with digging in the spurs, with the wall footings causing a bit of obstruction.

Not sure why the original posts decomposed so badly. I’ve no way of knowing how old they are, I moved here 8yrs ago and they were already like this. I don’t believe there is any source of water, but it’s a shaded area and north facing so the soil there can remain damp after rainfall, for a long time I guess. It’s interesting that the only two of the five posts that haven’t totally collapsed are the end ones.

 

[odgeuk]

The typical workaround is to dig between the old posts and set new.

Not sure that could work here. Not least because there is the wall section in situ, but also because it would mean the end posts would now be further away from the boundary ends, leaving an odd gap to fill (especially if planning to slot standard size fence panels in the concrete post grooves).

 

[aveatry]

I am wondering if those posts are so old that when they were installed that concrete gravel broads were not a thing so the owner used bricks. Maybe investigate what foundations the brick are on.

 

[odgeuk]

I am wondering if those posts are so old that when they were installed that concrete gravel broads were not a thing so the owner used bricks. Maybe investigate what foundations the brick are on.

The bricks do see to be on some solid footings. The footings are very neat on one side, being the same width as the brick work. But on the other side, they extend out a bit further than the brick coarse, which means potentially damaging the footings in order to dig in any spurs or alternative posts back from the wall.

I think I’m going to get hold of a mini Kango (the concrete will almost definitely be too solid for an SDS drill + breaker attachment IMO) and try to carefully break out the old posts. I am concerned though that it’s going to be near impossible to dig out a good enough hole for the replacement posts, to be able to fill with enough postcrete. The Wall and wall footings are going to make this very difficult.

 

[aveatry]

Have you thought about leverage them out.

 

[WalksWithTurkeys]

Can’t you remove a brick length each side of the post, remove and replace the post, then repair the wall? Mixing mortar is easy enough. The tools you will need don’t cost much.

 

[odgeuk]

Have you thought about leverage them out.

Unfortunately, only two still remain. The other three have broken off at wall level.

 

[odgeuk]

Can’t you remove a brick length each side of the post, remove and replace the post, then repair the wall? Mixing mortar is easy enough. The tools you will need don’t cost much.

I think this will be how it goes. I’m happy to mix up some mortar, just don’t want to destroy the wall footings.

 

[aveatry]

I think this will be how it goes. I’m happy to mix up some mortar, just don’t want to destroy the wall footings.

hopefully the wall footings were not poured the same time as the post concrete