Replacing Corner Fence Post (8ft) 4"x4"

Joined
4 Sep 2009
Messages
47
Reaction score
0
Location
London
Country
United Kingdom
i had to replace corner post and having spent quite some time removing old post and concrete base and am now left with a 'L' shaped hole, about 12" by 12". also the earth around the top of hole is sandy and not clay like or hard. has anyone any ideas as to how to proceed! the hole is around 30" deep and was thinking of using postcrete. i have heard of shuttering but no experience but thought maybe of tamping down earth to reduce size of hole might be worth a try
 
Sponsored Links
Joined
26 Feb 2005
Messages
2,772
Reaction score
143
Location
Gwynedd
Country
United Kingdom
Trying to get away with using just part of the hole is not going to work. So, shuttering is out of the question, from the conditions you describe.

I would be tempted to see if you could go deeper still, digging a narrower hole in the middle of your now huge hole. Will need a longer post though.
Or, just bite the bullet and fill the big hole with concrete.

Postcrete is more expensive than buying ballast and cement, and it sounds like you'll need a lot!
 
Joined
4 Sep 2009
Messages
47
Reaction score
0
Location
London
Country
United Kingdom
Hi Wabbitpoo, apologies but the hole is approx 20"x17" which is much larger than the 12"x12" i want. as the images show i had just started thinking about shuttering before your reply. i do not really want to place post in the middle of the hole as this would affect one of the boundaries which cannot really be changed due to a very large tree nearby. also i'd rather not go any deeper. i agree with you though that i think a lot of concrete is going to be needed if the only solution is to fill this crater!



 
Joined
21 Oct 2004
Messages
9,979
Reaction score
188
Location
Sussex
Country
United Kingdom
only solution that will provide a solid post is to fill the hole around teh post with concrete. its not that big a hole. anything else will simply allow the post and concrete to move over time.
 
Sponsored Links
Joined
4 Sep 2009
Messages
47
Reaction score
0
Location
London
Country
United Kingdom
Hi Thermo. would that be 1 part cement 5 parts aggregate? in terms of the finish could i leave the concrete 2" or 3" below ground level and backfill with soil and slope concrete away from post. what would be best for stability? thanks for your reply :D
 
Joined
21 Oct 2004
Messages
9,979
Reaction score
188
Location
Sussex
Country
United Kingdom
pretty much spot on. put the mix in dry into the hole and ram it well in, then when its all lined up and your happy add the water and let it soak through.
 
Joined
15 Nov 2005
Messages
77,987
Reaction score
4,936
Location
Goodwood
Country
Cook Islands
now that you have found it such a job to dig out the old post (did it rot?) you might be in the frame of mind to use a concrete post next time. At least it will not rot so you may not need to do the job again.

That's what led me to resolve to use only concrete posts.
 
Joined
23 Feb 2005
Messages
6,871
Reaction score
402
Location
Surrey
Country
United Kingdom
Much better to leave the concrete a few inches higher than the surrounding ground, sloping away from the post. A handful of pea shingle 'pebbledashed' into the exposed concrete will soften the visual impact of exposed concrete.
That way no part of the post will be in contact with soil and will be able to air dry after it's been rained on.
 
Joined
4 Sep 2009
Messages
47
Reaction score
0
Location
London
Country
United Kingdom
opinion appears to be divided as to whether the concrete ends above,at or below ground level so probably not that significant (but agreed to slope away from post so no moisture remains)
 
Joined
15 Nov 2005
Messages
77,987
Reaction score
4,936
Location
Goodwood
Country
Cook Islands
above is certainly better if you have wooden posts, as it can help reduce water ingress. But it will get down the crack in time and the post will rot, near the junction between "in the ground" and "in the air" where there is an ideal mix of air and water to support rot.

If using concrete posts, which do not rot, you can have the concrete just below the surface so it doesn't show.

A handy tip for making post concrete look neater, is to finish the great mass of it below ground, then put a small frame round the post a few inches high and put the last mix into it, so the concrete showing above ground is a small neat piece. A square frame can be made with scraps of wood, for a round one you can cut the bottom off an old bucket or large plastic tub or flowerpot
 
Joined
4 Sep 2009
Messages
47
Reaction score
0
Location
London
Country
United Kingdom
Hi Thermo,
i am still thinking about your suggestion to resolve my problem.

the top of the hole from corner of the L shape to the other corner at ground level is about 3' (36"!!) and the position of the post is off centre (towards the corner of the 'L'). Would i need to widen the hole to make the post the centre? (more concrete) would you advise on making the hole square. Or is it a case of filling with concrete and hoping for the best

As things stand, just adding concrete would create 'V' shaped (top heavy) concrete base,

i could perhaps dig a bit deeper and create a pyramid shaped/bottom heavy concrete base and finish the concrete 6" or so below ground level...this would mean the base of the post completely surrounded by concrete..

can anyone advise if shuttering is not a very good idea generally for post holes, or just in my situation.
 
Joined
15 Nov 2005
Messages
77,987
Reaction score
4,936
Location
Goodwood
Country
Cook Islands
shuttering between the concrete and the sides of the hole is not a good idea. The concrete should be surrounded by firm, well-compacted soil that has not been dug up. Hence you have to dig out all the disturbed soil and replace it with concrete. If you use shuttering, and then backfill afterwards, the concrete will only be supported by loose soil.

digging out the bottom of the hole will be good so that the base is surrounded by concrete and can't move towards the softer ground

if the hole is very big you can, for economy, pack round the post with large pieces of clean brick or broken concrete, so long as the mix packs tightly around then all and they set into a single solid mass
 
Joined
4 Sep 2009
Messages
47
Reaction score
0
Location
London
Country
United Kingdom
can anyone help regarding
put the mix in dry into the hole and ram it well in
do i add water initially to the proportions to create a dry/firm mix and then add water at the end of the day. thanks
 
Joined
23 Feb 2005
Messages
6,871
Reaction score
402
Location
Surrey
Country
United Kingdom
If using postcrete then water can be added later, you could water the hole first, to moisten it but let any excess drain away before adding the mix.
 
Joined
4 Sep 2009
Messages
47
Reaction score
0
Location
London
Country
United Kingdom
Hi Deluks, due to amount of concrete required i have decided not to use postcrete on this corner hole but to mix my on concrete can you advise re my question regarding when to add the water to the mix
 

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
Top