Question re concrete curb for fence

Discussion in 'Misc DIY' started by David Todtman, Apr 9, 2006.

  1. I am taking down my 3' white picket fence to replace it with an 'iron' fence
    of the same height. (I can weld so I'll make the new steel fence.)

    I want pour a continuous curb that will go under the fence. The fence posts
    (steel) will bolt onto the curb. I think I need to make the curb between 6
    to 8 inches wide--haven't figured this out yet. I reckon 6" would be okay
    in the sense that there is no substantial weight bearing downward onto the
    concrete. However, the fence posts will have base plates welded to them and
    I might need a wider curb so the bolts do not get too close to the edge (to
    prevent cracking the edge of the concrete out where the bolts go in).
    Comments on this hoped for and welcomed.

    Also, I am not sure how deep to go with the curb. We live on southern
    Vancouver Island with a climate like Seattle. We don't get much in the way
    of frost and it never goes deep. So, I thought I probably could go down
    around 16" below the ground surface and not have to worry about frost
    problems. (I think I'd like the curb to come about 2" above ground.) I
    don't know if this is right thinking or not so I'd be happy to get comments.

    Finally, I think I need to also be concerned about going deep enough so the
    fence could not be pushed over if somebody leans on it. Is 16" deep enough
    for that?

    Thank you in advance,
    David Todtman
    David Todtman, Apr 9, 2006
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  2. David Todtman


    my concerns wopuld be the posts rusting causing thew curb to crack.
    that happened to my and all my neighbors homes all the concrete porces
    had to be replaced or another work around found
    , Apr 9, 2006
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  3. I don't think the posts will rust. If they were set into the concrete, then
    there is that risk. I've seen what you are referring to--the metal just
    'melts' away from rust where it enters the concrete. My posts will not be
    set into the concrete but rather they will be fastened to the top of the
    concrete by base plates. The base plates will be welded to the bottom of
    the fence post. The posts will be painted which will protect the surface
    from rust.
    David Todtman, Apr 9, 2006
  4. David Todtman


    _Something_ will be going into the concrete: just make sure that it's rust
    free and you're good to go: concrete won't keep out water on it's own for
    the most part: so steel in it can rust and destroy the concrete work.

    As to the curb, the issue isn't the amount of weight yo're going to be
    putting on it, but how big and deep it needs to be to keep from moving
    about. This is non trivial. But are you planning on putting these in
    yourself? I have vague recollections of concrete guys with reasonably
    automated curb making devices offering ther services for lawn/garden
    edging who would both have a good idea what you need and be able to give
    it to you fairly cheap.

    , Apr 10, 2006
  5. David Todtman

    Ken Guest

    Hi David. Ken from Maple Ridge here. I'm a concrete contractor and here is
    my 2 cents. You have asked how high, wide and deep, right?

    #1 Height
    Here's something to ponder: Is there going to be grass next to the new
    fence? I'm asking because you could actually set the elevation of the
    concrete curb to your desired lawn height. Then mowing is much easier.
    (you'll be able to drive or push your mower on the curb.)
    Personally, if you don't mind weedwacking, it will be more visually pleasing
    if you do pour the
    curb slightly higher than the lawn or any other landscaping.

    #2 Width
    Since you DO know how to weld, why not make up some small steel plates with
    anchors on the bottom and actually pour them into the new concrete at the
    required spacing? After the forms are stripped, you'll be able to weld your
    fence posts to these. Not very nice if you ever have to remove a section,
    but it may work better if you will never have to remove them. With the
    plates installed in the curb, you'll be able to go with a 8 or maybe even 6"

    #3 Depth

    DO NOT get a curbing company to do this for you. They do not pour the
    curbing deep enough for adequete frost protection and you'll probably be
    able to just push over the fence after you mount it on the curbing. IF you
    want a permanent fixture, I highly recommend a small (but necessary) footing
    under your curb. You can easily get away with 16" wide and 4-6" thick. Pour
    the curb on top of this to whatever finished height you decide on.

    #4 One More Thing
    A couple rows of 10mm steel in the footing and a couple more in the curb
    will reduce movement in the curb after it cracks. IT WILL CRACK! You didn't
    mention the length of the fence, but it will have to crack to release stress
    due to freeze/thaw and shrinkage.
    Ken, Apr 17, 2006
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