How deep to set a concrete fence post?

2 Feb 2008
Reaction score
United Kingdom

How deep should you set a concrete fence post?

I'll shortly be erecting a fence using 7ft 9" posts, my initial plan was to use 1ft gravel boards and 5ft fence panels leaving 1ft 9" to set into the ground. Is this sufficient enough to leave me with a sturdy post?

All help and guidance appreciated.

Sponsored Links
Thanks Thermo.

So if I want a 6ft fence, I'll need to use 9ft posts sunk 3ft into the ground?

Would you strongly advise against a 7ft 9 post only being 1ft 9 underground? A third would be 2ft 6 so that's 9 inches short of a third - would that make a big difference to the strength? Are there any other conditions that affect the strength of a fence?

Thanks again.
no 1/3rd of 6 feet is 2 feet. if youre going into firm ground, you will prbably be ok with the depth you have
Sponsored Links
Hi Thermo,

The posts I was thinking of using are 7 ft 9, a third if that is roughly 2 ft 6. with a 1 ft gravel board and 5ft fence panel that only leaves 1 ft 9 which is 9 inch short of the third you suggested (unless my maths is wrong).

The ground is pretty firm. Do you think I'll be ok?

I've read that the hole should be a spade width square, is this correct? I can't see how you'd squeeze much concrete around the post with such a narrow hole. How big do you normally dig the holes?

k rod, stop confusing yourself! its 1/3 rd of the post height above ground. in this instance its 6 feet above the ground so you want about 2 feet below ground. If the post is 7 feet 9 inches (id be surprised as they are normally 7 feet 8 feet 9 feet etc) that means you will have 1 feet 9 inches below ground, or only 3 inches less than 2 feet. That will be fine.

you want to keep the hole as smalla s possible. this keeps the ground around it firm. the concrete just needs to be rammed in around it with a steel rod/wooden stick etc to get it nice and firm.

hope it makes sense
Right I think we're good now! This website is where I was thinking of getting the posts by the way ( - all seem to be +9".

Thanks for the help!
IMO it also helps, if you are using concrete gravel boards, to sink them slightly into the ground (discourages animals too)

in my case I made a bit of a trough and filled it with concrete mix for the gravel boards to settle into while I was setting the posts. this gives a bit of lateral support to the fence, which is where it is most needed
and don't forget to paint them brown so they will look like wood ;) honest, they will.
Oh god if i see that picture one more time, im going to take my kango to it. now go and paint your bloody gnomes!
Slightly off topic but.....

Where the fence will end and meet the path next to my house, presumably I use an "end" concrete post. Can you drill into these in order to attached a gate? Does it matter which side of the gate is attached to the end post, the hinged side or the handle side?

the best option is normally to bolt a wooden plate to the concrete post. You wont be able to drill it for hinges otherwise.

if you can hang the gate off a plate on a wall rather than the post.
How do you guys usually hold a concrete post in place whilst the concrete is setting to ensure it stays vertical?


DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links