Concrete sand vs. stone dust for flagstone patio

Discussion in 'Hardscaping' started by TwoTinySprouts, Jun 19, 2013.

  1. TwoTinySprouts

    TwoTinySprouts LawnSite Member
    Posts: 33

    Hi guys,
    So I'm making a pretty big flagstone patio. 6" excavation, 3-4" fine gravel (probably should have used road base, but too late now). Now, do i put 2" of concrete sand or 1" stone dust under the pavers? There's a lot of discussion online about this. What do you use? We definitely have hard frost in the winter, and it gets wet beforehand. I'm concerned with the sand "washing out" over time, but will the stone dust cause buckling? The pavers are man made 2" colored concrete. Thanks!
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  2. alldayrj

    alldayrj LawnSite Gold Member
    Posts: 3,752

    Is it a flagstone patio or 2" colored concrete paver patio?
     
  3. TwoTinySprouts

    TwoTinySprouts LawnSite Member
    Posts: 33

    I'm sorry, that was confusing. Paver patio.
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  4. zedosix

    zedosix LawnSite Silver Member
    Posts: 2,628

    Either would work, sand or stone dust. Sand for the professionals and stonedust for the guys who don't give a darn.
     
  5. Stillwater

    Stillwater LawnSite Platinum Member
    Posts: 4,800


    I don't entirely agree we have been in business since 1975 and throughout the 70's all of the 80' early 90's stone dust is all we used. The walks paths, and patios that still exist today are fine, although I do agree about the water retention I totally disagree with the statement professionals only will use concrete sand. If all our work failed we wouldent be around today. Stone dust is hear its not going anywhere it will be used by some not by otbers.
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  6. zedosix

    zedosix LawnSite Silver Member
    Posts: 2,628

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  7. zedosix

    zedosix LawnSite Silver Member
    Posts: 2,628

    The word stone dust doesn't necessarily mean one type of dust is the same as the others, in our area stone dust refers to limestone screenings which contains many fine particles most of them being powder. I agree some people are still using it and I did use it my first 15 years in business and your right a lot of the work is still there fine but I have seen when doing repair work pulling up the brick in the bottom of the brick is completely disintegrated from the stone dust reaction to the brick it's not common but I have seen it a few times over the last few years
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  8. zedosix

    zedosix LawnSite Silver Member
    Posts: 2,628

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  9. dnamadkate

    dnamadkate LawnSite Member
    Posts: 1

    Use concrete sand under concrete pavers. Compressibility is more uniform during tamping. Also a better material interface for polysand. As far as washout, be sure to have your separation fabric run up to at least the sand height on your edges that approach step treads. Stone dust is good for real slate and flagstone as long as you use a depth that is flexible enough to accommodate variable thickness pieces of flagstone.i have pulled up many pavers laid on stone dust and replaced it with sand to homeowners satisfaction.
     

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