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  1. #1
    Join Date
    Dec 2008
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    4

    Default Concrete Slab driveway rising

    We have several large trees around our car port. One or more roots is pushing up our concrete slab leading into the car port, leaving a 3 inch and growing drop off onto the car port slab. We can see one root squeezing between the two slabs. What is the best way to get the slabs even and prevent the roots from continuing their push upward? We have seen how to raise but never lower a slab.

  2. #2
    Join Date
    Aug 2007
    Location
    Maryland
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    1,667

    Default Re: Concrete Slab driveway rising

    The only thing you can do is cut the tree down and as the root rots the slab will come down.
    You could also sever the offending root from the tree, but that may kill the tree eventually or it may grow back.

  3. #3
    Join Date
    Aug 2008
    Location
    San Diego, CA
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    367

    Default Re: Concrete Slab driveway rising

    Sounds like Ed just pronounced the death sentence for a tree...

    But he's absolutely right. The tree's a goner if you want to save your slab.

    Good Luck with that chain saw. :-)

  4. #4
    Join Date
    Dec 2008
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    4

    Default Re: Concrete Slab driveway rising

    Okay...so we cut down WHICH TREE? There are two, one on each side. One is live oak and the other a sycamore. We suspect it is the root to the sycamore (and we hate it anyway so having it gone won't be a hardship) but the oak is growing massive and would cost thousands to remove and we would truly miss it since it is the centerpiece of the front yard with deck built around it. This could be a very emotional experience for us! And if we cut it, how long would it take to see that driveway sink back down? The roots could take years to disintegrate.

  5. #5
    Join Date
    Aug 2008
    Location
    Eden, NC
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    285

    Wink Re: Concrete Slab driveway rising

    How big is the concrete slab? If it is a reasonable size a good cement contractor could raise it and get rid of the roots underneath it. Then they could set the slab back down. If the slab is cracked or too large to do this, they can cut it get rid of the roots and smaller piece of slab and pour a new piece of concrete. This could kill the tree, depending if it is a main root you cut out. If you take the tree down and wait for the roots to rot it would make watching paint dry seem like a speedy process!!
    Calcats

  6. #6
    Join Date
    Dec 2008
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    4

    Default Re: Concrete Slab driveway rising

    Two cars can set on the slab side by side and that's about it. Not super big. At the time there are no cracks of any kind...it is raising up uniformly at one edge, next to the car port slab only. I don't know what you consider a "reasonable size". Seems reasonable to me but raising it might crack it. We have discussed the possibility of cutting the slab midway, braking apart the part closest to the carport and digging out the roots one way or another (we suspect this is all going to COST DEARLY!) Then instead of pouring more concrete, setting sizable (perhaps 4x4 or 5x5 squares of concrete like pavers in the place with grass between the squares. This would allow future access at a lesser cost when other roots decide to invade. We just worry about the unevenness this will cause over time. And the dirt and the mowing. And the breaking of the squares...yada yada. If the trees dies, which we suspect it will if we take out several bigger roots, then we still have the expense of the tree removal which for a tree that size may be several thousand dollars! Our income is linked to the housing industry in FL and need I say more! Income is slow these days so expenses like this are not welcome.

  7. #7
    Join Date
    Aug 2007
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    Maryland
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    Default Re: Concrete Slab driveway rising

    I had an experience with a black locust tree lifting a parking pad. I don't remember the exact timeline, but within a year or two the slab came down. The adjacent stump was ground out, so that might have hastened the root rotting. Black locusts are often used for fenceposts and are faily rot resistant too.
    Unfortunately trees that grow very large like oak and sycamore trees are often planted too close to structures. I have a big red maple that I planted too near the house & deck that needs to be removed soon, even though I will miss the shade it provides.

  8. #8
    Join Date
    Aug 2008
    Location
    Eden, NC
    Posts
    285

    Wink Re: Concrete Slab driveway rising

    Lakeside, the reasonable size is approximately 10'x 20', so you can prop it up to get to the roots. Since money is a problem (and believe me I know it always is, at least in my case),if you think the roots go completely across the width of the slab maybe you should remove the entire slab. You would be able to get to all the roots, using a stump grinder that you can rent from an equipment rental. Then, instead of pavers, I would put 2B size stone in the driveway and wait about 1 year. If no more root problems occur, you can pour concrete or put pavers down, whichever you like. But, it would be at your convenience and not because the roots are causing it to be addressed.

    Calcats

  9. #9
    Join Date
    Dec 2008
    Posts
    4

    Default Re: Concrete Slab driveway rising

    Well, it appears that the size of the slab is within the rhelm of "reasonable". Good idea about just yanking the whole thing out, renting a machine to get rid of the roots and then usuing gravel TEMPORARILY. We already have a crushed concrete drive that is a bugger for dust and dirt in the house. Gravel will be the death of our wood floors! Maybe we will just plant grass there for the time being. Good ideas. Now...where to get the money AND the desire to tackle the job?

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