Fence post in problem ground

[Ali]

I had a fence installed a while back, I weirdly enjoy fencing jobs but had a time constraint (neighbour putting house on market, wanted to increase the height in case the new one wasn’t as friendly - they turned out to be lovely). A couple of the posts leaned and the company came back and rectified the same day I called them which I thought was great service, they were a great bunch of guys and re-set the problem posts, even 3 or 4 months later.

Anyway, one of the posts is leaning again. The weather isn’t entirely blameless and I think the guys did the best they could with the conditions and materials at hand.

This sort of thing drives me mad and is probably why I never get anything done, but I’m going to fix it as I’m replacing another post anyway.

I think it’s probably gone because the ground is hard clay on one side and cultivated rose border on the other, probably with sand in it to ‘help drainage’.

Should I do anything more complex than extra concrete and stuffing as much rubble down the soft side as I can get away with?

Edit: to add, concrete posts

 

[Mark 5]

To clarifi, the existing posts, timber or concrete?

 

[Memmeddu]

To clarifi, the existing posts, timber or concrete?

Deeper in the ground would be my solution anyways

 

[roofman]

See this all the time when bags of ready mixed postcrete has been used, the posts start rocking in the wind and turn it back into powder...cant beat real mixed concrete for posts...rough sand,cement and 12mm stone.

 

[frank horton]

just an idea....
here the ground either solid rock or compressed sandy gravel that's like concrete.....
for fence posts or small conc foundations.
I use my Hilti to get 20mm rebar down in the ground by at least ,5m....sometime if I get thru the bedrock sheet the bar will go a full meter...
My drill is a worn 20mm but I still have to pound the rebar the last 30cm....
For ur job I'd weld a couple of heavy plates to the rebar to secure the post....

 

[Ali]

To clarifi, the existing posts, timber or concrete?

Concrete

Deeper in the ground would be my solution anyways

That would be the obvious thing to do, I will try to get 2.7m posts if available.

See this all the time when bags of ready mixed postcrete has been used, the posts start rocking in the wind and turn it back into powder...cant beat real mixed concrete for posts...rough sand,cement and 12mm stone.

I’ll definitely be using proper concrete, I’m sure that stuff can work for low fences in the right ground conditions but I’ve never trusted it either.

 

[Keithmac]

I sank mine in 3 foot+ holes filled with gravel and it has worked surprisingly well.

Not had any movement in the posts even in the worst winds.

 

[Welderpaul]

Yep, longer posts and 'real' concrete to get down to harder ground.

I hate getting jobs done by companies, there are a few that are 90% with what they do, but I have high expectations so try to do everything myself. Their desire to get to the next job/get finished as quickly as possible/get to the pub that day means I end up with a permanently substandard job.
Probably the reason I have a job list which stretches across two continents

 

[magnet]

Nail a foot on the bottom of the post. That will help to anchor it better in a deeper hole.

 

[tom2207]

drive aa few bits of bar / steel down in the botton too , gets you an extra few feet of purchase for very little cost and effort

 

[Porkypine]

drive aa few bits of bar / steel down in the botton too , gets you an extra few feet of purchase for very little cost and effort

That's the kind of thing I've done numerous times, banging the steel, bar, angle whatever, in at various angles in the ground below and to the side of the hole, making a 'hedgehog' of spikes the ends of which which are incorporated into the concrete and gives more purchase into the ground.
Handy way to get rid of unwanted scrap metal too

 

[Mark 5]

Concrete

That would be the obvious thing to do, I will try to get 2.7m posts if available.

2.7m concrete posts are widely available.

Remove/breakout the affected post and all its bedding concrete.

Redig post hole, this time 16in + diameter, 40in deep, fill with pea gravel, 4-5 inches, set and square your post burying about a 1/3rd of it then use Postcrete or some such to set post.

1 hour and postcrete should be set but leave for a day, then fix the fence.

 

[dave h 2]

You have to remember the postcrete is to take up all the space between the post and soil and 9 times out of 10 that's fine. The strength of the mix is irrelevant till you need to get it out.
If the soil is not compacted or very wet it will be squidged out of the way. Obviously the wider the hole the larger the amount of soil the post needs to move, so if they used an auger for the holes there's a lot of force on a small area.

Dig deeper, wider and if it's very soft soil at that spot try a 600mm slab on edge.

 

[Migmac]

You’ve got it, longer post further into the ground. The only time I’ve used postcrete was when I was putting in poles for the washing line. If I’m digging posts in, everything that comes out the hole, goes back in the hole - solid

 

[magnet]

You’ve got it, longer post further into the ground. The only time I’ve used postcrete was when I was putting in poles for the washing line. If I’m digging posts in, everything that comes out the hole, goes back in the hole - solid

Aye i never use concrete. Deep hole and tamp the soil back in tight around it.

 

[Blobber]

Were on clay around here and it doesnt matter what you do after 12 months of seasons wet/dry/wet/dry the posts end up flopping about, some of the ground shrinkage we had this year you'd loose a small child down the cracks!

 

[Pigeon_Droppings2]

Problem with post create is people assume 1 post=1bag which isn't always appropriate!

The trick is to have enough mass...just like the way a skyscraper is built!

 

[chunkytfg]

Problem with post create is people assume 1 post=1bag which isn't always appropriate!

The trick is to have enough mass...just like the way a skyscraper is built!

That was my first thought. I've recently re done some fences and I was using 2.5 bags of post Crete minimum for the 8' posts and even the 6' posts were getting 2 bags each.

 

[Kram]

An 8" auger hole and 60cm deep will need around 2.5 bags of postcrete a d I'd normally add any big rubble or half bricks found whilst digging, back in the hole.

A common problem is people just pour it in, they dont tamp the postcrete down, which is always going to be weak. Once you add the postcrete you only get a couple minutes to ensure its square and to tamp it down hard.

 

[Pigeon_Droppings2]

I usually use 2-3 bags and never had an issue.

We're on clay here...my gravel board is resisting a 0.5m height differential but there's a lot of mass under those posts!