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Something to dissolve wood?

DougR | Posted in General Discussion on August 31, 2006 08:05am

I have some rotted fence posts that need replacement. I thought it might be a real time saver if I could remove the old wood down in the existing concrete footing and just slip a new post down into the existing square hole.

The first 3-4 inches below grade are so soft that it’s easy to dig out the rotted wood. But below that the wood is still solid so it’s very tough to get the rest of the old post out. Does anybody know of a technique or product that would soften up the bottom portion of the old posts enough to make it easy to dig out the old wood?

The alternative is to dig out the old concrete plug only to pour new concrete in the same hole to set the new post. Lots of time and sweat.

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  1. piko | Aug 31, 2006 08:16am | #1

    Some people bore several holes into the bottom, pour in kerosene, and light it. Probably one of the dafter replies you'll get, tho.

    All the best...

    To those who know - this may be obvious. To those who don't - I hope I've helped.

     

    1. User avater
      CapnMac | Aug 31, 2006 08:27am | #2

      pour in kerosene, and light it. Probably one of the dafter replies you'll get

      Not really.  Putting kerosene into augered holes into tree stumps certainly seems to make them "rot" faster (but no lighting the kerosene).

      Now, whether what rots a live to dead tree stump and what rots a PT fence post . . .

      I once used a double-ended screw (half lag screw thread, half machine thread) attached that to soem all-thread with a union, and used another union with a pad-eye on top, to be able to reach into rotted posts and still have the eye above ground.Occupational hazard of my occupation not being around (sorry Bubba)

      1. User avater
        IMERC | Aug 31, 2006 01:01pm | #6

         and what rots a PT fence post .

        concrete.. 

         

        Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->

        WOW!!! What a Ride!<!----><!---->

        Forget the primal scream, just ROAR!!!

    2. DanH | Aug 31, 2006 12:49pm | #5

      Daft is setting the posts in concrete to begin with.
      If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

      1. user-197115 | Aug 31, 2006 07:56pm | #13

        Unless you're using concrete fence posts!

  2. restorationday | Aug 31, 2006 09:16am | #3

    A 3/4" auger bit on an extension will remove enough wood that you should be able to loosen and remove the remaining chunk of wood. If you hit each corner with a hole there won't be a lot of the post to hold itself in the hole. I said 3/4" but the bigger bit you have the better and use an auger as a paddle bit will not work very well into endgrain.

    This is not the quickest method but it is a lot quicker than rotting pt.

    -day

  3. Piffin | Aug 31, 2006 12:37pm | #4

    The reason the posts are rotted is because they are set in cement.

    Use gravel to seat the new posts and they will last a lot longer and be easier to do.

     

     

    Welcome to the
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  4. User avater
    IMERC | Aug 31, 2006 01:03pm | #7

    dig it all out and use gravel instead of concrete...

    the concrete rotted the post to start with...

     

     

    Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming

    WOW!!! What a Ride!

    Forget the primal scream, just ROAR!!!

  5. bigfootnampa | Aug 31, 2006 02:44pm | #8

    It's lots easier to dig the old plugs out.  I'd like to know why the part of the post that is still in the concrete is the solid part if the concrete is what rotted the posts???  And the answer is that the concrete had no effect except to insulate the bottoms of the post against the bacterial attack that did in the post where it was in ground contact.  Get an electric jack hammer and break up the cement so that it comes out in reasonable sized pieces.  A good digging bar is very helpful for prying up the pieces.

    1. User avater
      BillHartmann | Aug 31, 2006 03:04pm | #9

      "I'd like to know why the part of the post that is still in the concrete is the solid part if the concrete is what rotted the posts???"That is true at the BOTTOM of the concrete. But as he said the first several inched IN THE CONCRETE is very soft. That is where it failed.And it failed there because there is a gap between the concrete and the wood and water gets in there and soaks the wood and keeps it wet.

    2. User avater
      IMERC | Aug 31, 2006 03:04pm | #10

      the CC holds the water to the post and won't let it drain...

      more reasons for rot... 

       

      Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->

      WOW!!! What a Ride!<!----><!---->

      Forget the primal scream, just ROAR!!!

    3. MikeSmith | Aug 31, 2006 03:06pm | #11

      the concrete did have an effect... it kept the rot zone wet / dry

      the part encased in concrete was permanently wet so it didn't rot

      the part above the concrete was kept wet but also had oxygen to encourage rot

      setting posts in drainable material like crushed rock or gravel will prevent this

      a PT post set in material that allows drainage will not rot..

       but one set in concrete ( or anything that will trap water ) willMike Smith Rhode Island : Design / Build / Repair / Restore

      1. DougR | Aug 31, 2006 05:29pm | #12

        Thanks everybody for your comments. Using an auger bit to hog out some of the old post sounds feasible to me. The kerosene doesn't sound very practical.I understand that the lack of drainage with the concrete is the ultimate culprit, however, the posts lasted almost 10 years. The gradual buildup of earth eventually covered the top of the concrete and left the wood sitting in moist dirt. For these repairs I will replace the post, scrape back the dirt, and form a little drainage collar at the base of the post out of patching cement.I inherited this particular fence, but the next time I install a new fence from scratch, I will definitely set the posts in crushed rock and not concrete.

  6. SBerruezo | Sep 01, 2006 08:08am | #14

    Of course, you can always hook them up to the truck and rip them out ;)  It usually works like a dream.

     

    Young, poor, and eager to learn

    1. gb93433 | Sep 01, 2006 08:49am | #15

      If you use conmcrete then you must have gravel in the bottom otherwise the concrete traps the water and the wood rots. Whenever I use wood and concrete I use long metal straps and use the straps to hold the post. If you put the straps so that the one strap is on the front and one at the rear it is stronger than if you put them on the side because if the wind blowws or someone pushes on the fence then it must pull one strap and compress the other. If you do not then all that needs to happen is for the strap to be flexible for the post to move. If put the right way then the straps do not have to be very big. If put the wrong way then they must be thick and wide and most likely the concrete will not hold them either.

  7. RyanBrant | Sep 01, 2006 09:59am | #16

    The wood about 8-12" down (around here) starts to get solid again and is difficult to remove.  We've done by putting a large lag screw into the good wood and lifting with jack - the type of jack that pulls up rather than pushes up.  Like a hoist without the cable.

    Best bet is to get a breaker bar - about 5ft long, steel, with a (wood type) chisel point.  Hit the corners of the concrete, bisecting them with the point.  Hit hard.  Do this 5-15 times and the concrete will break.  Voila, 4 pieces of concrete and a post in the middle that can be pried up and/or broken into maneuverable and removable pieces.   Try to maintain the soil integrity around the footing.  That means your new footing won't be huge.

    Bar's around $30-40 I think, and a versatile tool to have around.

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