I had most of my side fence go down in a storm last summer, and finally had it replaced in December. The work was done by a local company that has an excellent reputation and I am very pleased with the new fence. The fence was not inexpensive, but it is stronger and better built I think, than the old one, so it should hold up for many many years. I will be replacing other old fencing in my yard, in the coming year or so, and was considering using this same person. But one thing this guy does, insists on, is to NOT pull up the old post concrete. He says that to do so leaves the ground unstable for the new post. But plenty of other people do this, don't they?? I mean, you just pour new concrete in the same hole. That is what I and the BF did when replacing posts last year. This guy cuts the post off level, and places the new post next to it. This was fine on the section that he replaced, but one of the sections I want to redo next year has the existing gate post right next to my side garage door. And that is where I want it. He is saying that he would have to put the new post behind the old one since he does not pull up the old concrete.

Is there any logic in this or is this just a guy that doesn't like the extra work involved?

 

I think it depends. Yes, you really can not remove the old concrete without disturbing the surrounding soil. If you were to dig out all the loose soil so the new concrete had firm, virgin soil to bear against it would be good. But I think most people leave the loose soil in place which will make any new pour less stable.

 

All fence guys do that. If you want to try to pull up that concrete for him, I'm sure he would say be my guest. Its not as easy as you think and after you work on it for a day or two I think you will come around to his line of thinking. There may be a few situations where the old concrete would NEED to come out but unless you want a backhoe digging up your yard and possibly a large section of your driveway, its usually best to find a work around if possible.

Pretty sure you wouldn't like the extra cost involved.

 

Oh I have dug up the concrete before. It is certainly more work, but I was questioning whether or not it was the norm to NOT do it. I had never heard of this before. Thanks for your response!

 

Basically, TIME = MONEY
Cutting the post saves the fence installer the extra work of removing the posts and disposing of all that concrete.

Nah, all you really need is some water, a towing chain, and an old fashioned bumper jack, and some scrap 2x4s.
Pour water around the post. Rock the post back and forth to loosen it up. Wrap the tow chain around the base of the post. Put the hook over the 'pin' of the bumper jack.
Lay 2x4s on the ground so they're NOT on top of the concrete and set the base of the bumper jack on the 2x4s.
Jack the post out of the ground. Repeat.
"so easy a child can do it" https://youtu.be/fS0TD4GaEvM

 

How about when there is no post or the post has either rotted off or breaks when you pull it? Or when the concrete is 12" in diameter and 3 feet deep.

 

That is a different story, for sure. But none of mine are rotted or broken off, or have that much concrete so that would not be the case. When the time comes, I will probably pull up the one by the garage - I want my fence to end at that same place - behind that concrete would mean a foot back. I'll do it myself.

 

Use a T-post. Drive the T-post into the old wood, that gives you enough leverage to wiggle the concreate back and fort, widen the cylindrical hole into a cone, and then you lift the concrete out.
With a 12" concrete pour, a 4x4 post is about 3" thick at the corners. About 5 good whacks at the base from a two handed sledge hammer will break the concrete corners, repeat for the OTHER 3 corners and you have 1 fence post and 4 shards of concrete. Remove the post, and then use a pry bar to pop the concrete segments into the center void to remove them. With a bit of practice, you get a hole that allows you to drop in a new post and just pour in new concrete.

 

Not to hijack this post but I've thought of renting a concrete chainsaw ($150/day) and doing some cuts to remove the old concrete. Hitting the old (aged/solid) concrete with a sledge will definitely do very little to the fence posts I've encountered. Just worried that the chain/blade hitting the dirt might be bad.

 

As long as you something to grab on to you can use the old tire trick and maybe a lawn tractor or even the car if you can maneuver it close enough.
But to answer your original question, removing the old concrete is not typical. It's best not add concrete at all if possible. But soil conditions and how far you can sink the post will determine that.

 

Diamond chainsaws are awesome. Just wear rain gear and irrigation boots since you are supposed to connect a hose to it as you cut.