Fence posts and underground cables/pipes

s7ryf3925pivug

Going to put up a fence using fence post spikes. Seems to be a better option than concrete for us because we will change it in about a year. How do you make sure there are no cables or pipes undergroubd before driving a steel spike into them though? I saw a cable avoidance tool but it is several hundred euro which is too much for a one-off job.

_Brian

Cables and pipes should be 600mm+ down, I doubt you will be going that deep.

s7ryf3925pivug

_Brian wrote: »

Cables and pipes should be 600mm+ down, I doubt you will be going that deep.

They do go that deep.

foxy farmer

You can hire out the cable avoidance tool from tool hire shops

s7ryf3925pivug

Hm it doesn't work with plastic pipes. No idea if there might be plastic pipes.

policarp

dig away, the chances of meeting live unprotected wires are slim.
If you do Trip switch will save you.

s7ryf3925pivug

policarp wrote: »

dig away, the chances of meeting live unprotected wires are slim.
If you do Trip switch will save you.

I'm concerned about damaging a pipe or cable, not hurting myself. The planned location of the fence is somewhere that I think could have cables or pipes, based on the layout of buildings there.

s7ryf3925pivug

Maybe I should just go with concrete. I don't think that needs the same depth. How difficult is it to remove a concrete base for a fence post though? It sounds difficult... Maybe I need to ask that on a different forum actually.

s7ryf3925pivug

Checking with the council is advised elsewhere, however one of the structures has no planning permission and therefore presumably the council will not have details of cables and pipes connected to it.

Melodeon

_Brian wrote: »

Cables and pipes should be 600mm+ down, I doubt you will be going that deep.

"Should be" and actual reality may be entirely different things, given the variability of building practices over the years.

In an unknown situation like this, but where you know there have to be various pipes and cables 'somewhere' about the place, you're probably unfortunately looking at manually digging the postholes. Carefully!

I came across a situation a good few years ago where a homeowner got a wet spot in the middle of the front lawn.
With a bit of digging, they discovered about 20 meters of 1/2" black hydrodare pipe coming in under the fence from the neighbours and coiled around a few times on top of the builder's rubble, and thinly (6" or so) covered over with topsoil to make the lawn. :rolleyes:
The leak was from the bit of corroded copper pipe and pair of jubilee clips that 'joined' the pipe to where it dived into the foundations of the house, to emerge inside at the back kitchen sink.

Who knows what evils are buried out of sight around houses these days.

jack of all

Melodeon wrote: »

"Should be" and actual reality may be entirely different things, given the variability of building practices over the years.

In an unknown situation like this, but where you know there have to be various pipes and cables 'somewhere' about the place, you're probably unfortunately looking at manually digging the postholes. Carefully!

I came across a situation a good few years ago where a homeowner got a wet spot in the middle of the front lawn.
With a bit of digging, they discovered about 20 meters of 1/2" black hydrodare pipe coming in under the fence from the neighbours and coiled around a few times on top of the builder's rubble, and thinly (6" or so) covered over with topsoil to make the lawn. :rolleyes:
The leak was from the bit of corroded copper pipe and pair of jubilee clips that 'joined' the pipe to where it dived into the foundations of the house, to emerge inside at the back kitchen sink.

Who knows what evils are buried out of sight around houses these days.

Sorry to quote a long post, but sad reality is you can't assume anything where building and services are concerned- unless you assume the worst! If there's a corner to be cut, time or money to be saved,you must assume this may be the case- caveat emptor I suppose!

Lumen

Alfred Petite Racer wrote: »

Maybe I should just go with concrete. I don't think that needs the same depth. How difficult is it to remove a concrete base for a fence post though? It sounds difficult... Maybe I need to ask that on a different forum actually.

IMO the best approach for fence posts is treated wood directly into the soil as deep as you can with as little soil disturbance as possible, driven in with a post basher. This is completely routine.

Concrete and wood don't mix, and a short post in shallow concrete will not be stable.

Don't dig, you'll loosen the soil.

If you're concerned about hitiing something, do it on a Monday so people are available to fix it, but the odds are that you won't.

Why do you think spikes are better?

Calahonda52

Treated timber, unless with banned substances like creosote, when permanently wet in soil, will only last 5 years or so

Lumen

Calahonda52 wrote: »

Treated timber, unless with banned substances like creosote, when permanently wet in soil, will only last 5 years or so

I have a post and rail fence along my driveway with not a trace of creosote that was put in in the late 1980s, and while it's falling to bits now I reckon it was fine for the first 20 years or so.

There's also a 6ft high hit and miss fence running along another boundary that has sections still just about upright, again put in in the 1980s, and that would have significant wind load. But that's mostly kept up by hedging.

seamus

Whether concrete works, depends on the height of the fence. I've had no issue with wooden fence posts + postcrete for a 600mm fence, it's rock solid. I went down about 300mm, as far as I could get with minimum effort.
That said, there's zero load on it, not even wind. The boundary fence is wooden posts set in concrete, which my neighbour put up, and is sagging badly.