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Pavers over existing concrete slab

Discussion in 'Hardscaping' started by LB1234, Nov 1, 2007.

  1. LB1234

    LB1234 LawnSite Gold Member
    Messages: 3,208

    We have a possible job where there is an existing concrete slab where another contractor would like pavers installed over the top of it. I explained that I like to rip the concrete out and basically start over since I know that my base won't settle, crack, etc. He said he would rather not do it since he wants the job done this year...I figure I only have a few weeks left before having mother nature take over.

    The facts I know so far...there is an inground pool with cement pads going all the way around it. It is in very good shape...no settling, no cracking, etc. However, 'behind' the poured concrete around the pool is another concrete slab that has settled really bad. The homeowner years ago decided to install a deck over it so the pitch wouldn't be a problem. At least from an aestetic point of view.

    So, can I place pavers over an existing slab? I beleive I could install weep holes through an existing slab and then lay fabric down to keep the sand from filtering through and settling the pavers.

    However, my problem is what about a slab that has real bad pitch? Lets say it drops 12" over a 8 foot span. I'll no more moday since I'll be taking a look at the job then. I just would like some ideas on what to look for when I go there. I might just turn around and just not accept the job. Again, thats why I'm writing.

    thanks :waving:
  2. hoskm01

    hoskm01 LawnSite Fanatic
    Messages: 5,690

    If the concrete is not a sufficient base (level and true to your pavers) then I wouldnt go for it. 12" off is quite a bit. If the general doesnt care about quality and integrity of the bazse/product, you dont want to work for him.
  3. Team-Green L&L

    Team-Green L&L LawnSite Bronze Member
    Messages: 1,775

    You can special order an overlay paver that's 1.5" thick from Pavestone, but I would only do that if there isn't a 3" clearance for a full-sized paver. As long as the concrete is good you can overlay, but I wouldn't put a guarantee on it because of the unstable base. I would only move forward on level concrete !!!

    Simply use concrete adhesive around your border and fill in the middle. I strongly advise customers against this, which I see you've done, but my Pavestone rep has been adamant that it's done a lot in municipality projects and I have to assume he knows. We've done 10-15 of them and I haven't gotten a call-back yet. The first one was in 2004, so I'd say go for it.
  4. ChampionLS

    ChampionLS LawnSite Bronze Member
    Messages: 1,066

    12" drop over 8'? omg thats a ski slope. We've laid pavers over broken/cracked concrete slabs with no problems. I would make sure the reason for cracking isn't a big tree root and/or the slab is somewhat stable. As long as it hasn't settled enough to throw your final grade off, then all you really need to do is cover it with geotextile and screed a new sand layer. Tamping is the only issue, as the pavers pack down quickly with a dead solid base. It goes rather quickly.
  5. Team-Green L&L

    Team-Green L&L LawnSite Bronze Member
    Messages: 1,775

    Hey ChampionLS,

    I have to inquire as how your using sand atop the geogrid. I would like to use sand, but haven't found a way to use adhesive (on the soldier course) with sand. Seems that you would have a grade change from the border with sand. Maybe I'm just not seeing something???
  6. RockSet N' Grade

    RockSet N' Grade LawnSite Silver Member
    Messages: 2,454

    LB........I would look at the slab and see if there are cracks in it and how wide. I would also see if you can determine where the sprinkler system is and if this area gets alot of drainage. I would also look under the concrete edges and see if the slab is hanging in the air or has some base left. Maybe "tap" the concrete slab with a hammer to hear if there are hollows under the slab. I think that is what I would do, if I had to..........BUT, my gut tells me "run!". It doesn't take that much to rip up concrete and start with a solid base. All you really have at the end of the day is your reputation and integrity and if the job starts failing no one will remember you told them so, all they will perceive is that you did a crappy job. I try my best to do it the best I can every time, or pass........

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