How to remove posts from concrete

[phy6bjh]

Hello
I wonder if someone can help. I have a shed that is supported by large oak posts (9 inch square) that have been set into a mix of concrete and rubble below ground level. The lower end of the posts are rotting and I want to cut them off and set them either on staddle stones or metal posts that will rest on concrete pads. This will ensure that the remaining good wood will not rot any further I hope. The area around the posts is paved with slabs and quarry tiles. The problem is how do I remove the lower end of the posts from the concrete so I can backfill it to make a concrete pad. I've looked at post pullers but there is a problem getting them into place, attaching them to the stubs and they may also pull up the tiles etc. I was thinking that maybe I could drill holes in the stub until the structure is weak enough to break apart and remove the bits. Typical stub length is about 2 and a half feet. I'm not sure what sort of drill bit to use - is a wood auger appropriate? Parts of the post ends are still sound and rock hard. Any advice greatly appreciated.
Cheers
Bryan

 

[Guggs]

I remember a bloke telling me this .
Try burning it out . Pour a drop of petrol down the hole , let it soak in then set fire to it . Once it's all burnt out just remove the ashes - debris .
Obviously with great care !

 

[Alex H]

I remember a bloke telling me this .
Try burning it out . Pour a drop of petrol down the hole , let it soak in then set fire to it . Once it's all burnt out just remove the ashes - debris .
Obviously with great care !

Having just tried to remove a large (1m across) walnut stump, which was / is hollow, by this method, although using wood and NO petrol, I have to say your 'bloke' was telling fibs

I still have the stump intact, but now it has a hole in the bottom :lol: :lol:

 

[midnightlunchbox]

Could you not just bore out the stump with a decent sized drill bit? It might take a while but all you'd need to do then is give it a clean out with a chisel or cold chisel? That's probably what I'd try.

 

[Deejay]

Morning Bryan

If you've left the top on the stumps try to lever them out.

Tie something strong, like a scaffold pole , to the bottom of the post with say a foot sticking out on one side and six foot on the other side of the post.

Put a bit of wood down under the short end of the pole to protect the flooring and heave up on the long end. Pack up on top of the protective wood as the post comes out .

Good luck

Dave

 

[blackrodd]

I've been in this situation. What worked for me was to drill down with a long masonry bit and note when
cement dust comes up, this tells you the depth so you don't ruin the auger which is next to use, knock off an inch or so
just to be on the safe side,for the depth.
Drill out the middle of the post right across, to weaken it.
As the post is wet, being in the concrete, it will have swollen and jammed, this is why you set fire to the stump, to dry and hopefully shrink the remains, which after a bit of chiseling and cross drilling should all come out.
I replaced a length of fencing posts like this that would have meant digging up slabs etc that were laid several years after.
I did measure each post carefully and made a note of the exact size each time, and belted in the replacements.
Although a bit long in doing, I did save a load of work and disruption as the slabs were discontinued marshals.
HTH, Regards Rodders

 

[Setch]

I've had success levering them out, using a 6" coachbolt to screw into the stump, and a 6' fence post as a lever. IIRC of 3 stumps I tackled this way 1 failed, the post wouldn't hold a screw well enough. The other two worked perfectly, and slid out with a noise like a cork popping.

 

[andersonec]

I remember a bloke telling me this .
Try burning it out . Pour a drop of petrol down the hole , let it soak in then set fire to it . Once it's all burnt out just remove the ashes - debris .
Obviously with great care !

It's the fumes which burn, not the petrol.

Andy

 

[ACF]

Sounds like you haven't cut the posts off yet. So if you can cut off the posts on "good" wood then "plan A" would be to get hold of a steel pole or stout wood and attach to the top of the post with chain or webbing. Put one end of the pole or wood on a block and a car jack under the other. Raise the jack and the stump should come out if the lever and jack are strong enough! "Plan B" would be the drill, petrol and patience method which has worked for me in the past.

 

[phy6bjh]

Dear Everyone
Thanks very much for your prompt and very helpful replies - I use other fora and haven't had such good relies before. I'm now going to discuss these ideas with the others. Hopefully if there are a few questions I can ask them here. It will be a couple of weeks before we have a go so I'll return then and let you know the outcome. Thanks again.
cheers
Bryan

 

[rafezetter]

Am I right in thinking you are intending to cut off the post flush with the ground so that you can use the rest of the post in situ? Is the post going to be moveable after the cut or is it going to still be structurally tied into the shed somewhere at the roof, because if it is there will be very little give at the ground for you to move it out of the way enough to try the lever trick.

If the support post is still going to be tied in then what you'll have to do will be to put accro props either side and jack up the shed at that point only a few inches at the most - and possibly less depending on how much "give" the structure has - taking all the weight, then cut through the beam flush at ground level.

This will only leave you with minimal clearance to move the post aside then you'll have to drill down, probably diagonally to clear out the remaining wood.

If close to the bottom it seems as though the wood is still hard (which could be the case) then a possible alternative solution to drilling out all of it would be to drill holes and hammer rebar into them and create a piling, preferably at an angle to create a larger footprint, as it's probable the concrete does not go all the way to the bottom of the post stump, and the stump bottom is actually below the concrete level, so any remaining stump can happily rot away as the new pour concrete in the hole is being supported by rebar once all the wood rots out. If you are a belt and braces sort of guy you could also drill a few holes into the sides of the concrete hole and slot some cut lengths of rebar / threaded rod to create a sort of web effect in the hole, that way the weight will be distributed over a wider area and the new concrete poured into the hole will be mechanically joined to the existing surround thus making that section structurally part of the whole.

For the new post base, don't just plonk it on top of a slab, as the post will wick moisture up from the slab which will in turn be wicking moisture from the concrete - use a DPC to cover the base of the post / slab contact at the very least, and preferably try to soak it in preservative as well; get a baking try with very low sides and slide it under the post, then fill the tray with preservative and let it sit - longer the better - you might be able to do this while you are working on the hole.

Hope all that was clear enough and sorry if I'm teaching you to suck eggs

 

[Alex H]

Thought I might add another suggestion, that I've just seen in practice by one of my neighbours.

He has wooden gateposts, one of which has rotted at the base, which are set in concrete. After much swearing, cursing and failing to remove it by first trying to break the concrete, then trying to dig the wood out with a great big lump of steel, he found the ideal solution - a chainsaw :shock:

By the end of the day both post stumps had been removed in this fashion. Although he is English, the traditional French method of use was used - no gloves, eye or ear protection :roll:

 

[dickm]

........... with, presumably, a concrete proof chain!!

 

[wellywood]

Once you've cut off the posts you could try using post holders (see pic) set into your new concrete base. Cut the posts back to good wood then fit the holders before pouring the concrete (having temporarily supported the structure). This means you don't have to worry if the bottoms of your newly cut posts are all flush with each other as any difference will be taken up by how much of the saddle 'spike' is in the concrete. The saddles keep the post bases clear of the ground and stop them rotting.

 

[adrspach]

What about (if you have about a foot or more post left above the ground) to drill it through horizontally, put through thick steel rod and use two jacks or lever on oposit side to pull it out?