Concrete fence post

Stevieh · 6 Feb 2007

Hi ( I'm really sorry about the length of this question it's a bit tricky to explain)
I need to replace some old concrete fence posts which have recently broken off. If they were straight into the ground i'd be ok but they sit on a raised level of concrete which acts as a retaining wall for the elevated tarmac carpark the other side.The existing post would have been 5ft above the retaining wall ( which is 8 inches wide 2 feet deep 40 ft long) and passes through the 2 foot concrete and appears to go into the ground.Obviously this would be a major job to get this post out of the ground, disturbing my driveway,a large chunk of the wall and the possibility of collapsing the carpark.
If I cut the old post out at my driveway level is there any reason why I couldn't use a 7ft concrete post placed in the cut out section of the concrete wall above ground level secured with fixings and then the remainder of the wall re-concreted ?
My concerns are it will be in 2 foot of concrete and totally supported the carpark side but only by 4" of concrete at the front (driveway side)
Thanks for your patience and I would appreciate any ideas.

ModernMaterials · 7 Feb 2007

can you provide any photographs or try and make your explanation a bit more simple for us?

i would like to try and help but i cant really understand the problem

Stevieh · 8 Feb 2007

Hi
thanks for taking a look. I have photos but I have little chance of successfully posting them on here so i'll try to explain a bit better.
the ground is at 2 levels with the fence border on the high level, looking from the carpark side the fence is 5ft high.
Looking from my driveway side the 5ft fence sits on a 2ft high concrete edging.
with the old post out a u-shaped section of concrete is left and I would like to place the new post into this section of concrete (not into the ground at driveway level) shutter the front and refill with concrete.I know the post will not move in 3 directions but i'm worried that in time the new section of concrete will break out allowing the post to fall onto my driveway.
I hope this is a bit clearer and I appreciate your ideas.

libby lou lou · 8 Feb 2007

no clearer to me

Deluks · 8 Feb 2007

I understand completely, my garden fence is the same. Alleyway on the other side sits higher than my garden. I also have the same problem, with a couple of my concrete spurs snapped off and hanging on the rebar. I'll get round to fixing it one day but at the moment haven't really worked out how to. I'll post some pics of mine tomorrow so peeps can get a better idea of your problem.

Stevieh · 8 Feb 2007

Thanks deluks I was beginning to think that I was the only person in the world with a fence like this! similar pics would be great .... cheers

Thermo · 8 Feb 2007

i think im with you. you effectivly see concrete wall, then the post then concrete wall as you look along it? It is a difficult one, as the ideal would be to re concrete them in but that will mea a hell of a lot of making good. is using some small steel plate an option. If they are longer than the width of the post and drilled out at each end, they can be rawlbolted into the face of the concrete wall either side of the post. If you use three on each post that should be more than sufficent to hold it.

hope that makes sense!

got my thinking head on now. Whats behind the post when you take it out of th hole? presumably there is some concnrete from the car park construction? Again you could drill through the posts and into the concrete behind, then use rawl bolts or chimcally fix threaded rod into the concrete and bolt the post to it..

Hope that makes sense as well!!

JohnD · 8 Feb 2007

Can you bolt into the raised concrete bank?

Stevieh · 8 Feb 2007

I'm thinking of bolting plates across the post into the existing concrete edging belt and braces and all that!
I'm not sure what's behind the post yet ....more concrete hopefully!
I'm guessing galvanised plates would be useful and steel plates would just rust or am I being too careful here?

Deluks · 9 Feb 2007

Steel plates will be ok, you can get galvanising spray, to keep rust at bay. Or hammerite 'em.
As you can get at 2ft of post below the top of the concrete, fixing one big plate, or 2 at top and bottom, should give a firm fixing.

For now, remove the post, see whats behind and take it from there.

Stevieh · 9 Feb 2007

Tomorrow is post removing day!!
Actually a chap at work had a good idea. He suggested that when I cut out the section of concrete to cut it like a dovetail, smallest length at the opening this would alay my fear of the concrete section working loose over time, obviously it wouldn't fall out as the back would be wider than the front.
Thanks for the plate suggestions.

Deluks · 9 Feb 2007

Not a bad idea, but will be tricky though, how can you remove the back part of the post deeper down than the front, without damaging the rest?

You've just given me another idea though, use metal rebar to join the old and new post. Drill holes in each and insert pin with resin. and I'd still go for the steel plate too.
At this rate your fence posts gonna look like Barry Sheene's leg.

Thermo · 10 Feb 2007

not tried cutting the concrete posts yet then! they tend to spall and fall apart quite easily onc you start playing around with them. Drilling it for the new rebar will not be easy due to its size and the aggreagte they use in them. As for cutting it like a dovetail youll probably have enough problems getting to it to cut it off at your ground level on your side.

Stevieh · 11 Feb 2007

Post not out yet but the concrete is out, dove tail looks good. Looks like there is enough there to bolt plates to. Very hard concrete/ flint mix 9" diamond wheel and kango made mincemeat of it.
I've had to leave it for now due to weather/ screaming toddlers and I can't get back to it for 3 weeks due to other commitments (really annoying)
Thanks everyone for your input I really appreciate it.

ModernMaterials · 13 Feb 2007

I reckon you should get the guy who came up with that dovetail idea to start posting on here....

Like you said, belt and braces. So if you can fix a plate to the front or back of that post inside the dovetail aperture, im pretty sure it aint gonna fall forwards.

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Concrete fence post

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