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Uneven concrete slab problems

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  1. #1
    Apprentice (new member)
    Join Date
    May 2021

    Default Uneven concrete slab problems

    Hi guys, I have a old shed that has a VERY uneven concrete slab. The fall from the highest point to the lowest is at least 70mm, on top of that there a rises and falls, the slab is about 42m2. I'm having a bit of trouble figuring out how best to fix this. I've thought of a couple of options and would love to hear some feed back and/or suggestions.

    Option 1:
    Put down level battens and put flooring on top of that. This will be tricky as the fall is so severe, the floor would be slightly higher then the door, so I'm thinking of maybe grinding down some of the high points and then doing this.

    Option 2:
    Poor fresh concrete over the whole slab. This would be the easiest option but I've been quoted $3500 which in not keen to spend.

    I've attached a few photos showing how un even it is, the pine battens are level. I'd love to hear any other suggestions. Thanks guys.
    Last edited by phild01; 2nd May 2021 at 11:34 PM. Reason: pic links

  2. #2
    3K Club Member johnc's Avatar
    Join Date
    Jul 2004


    perhaps do a screed, although if it is to thin it will break up.

  3. #3
    Community Moderator phild01's Avatar
    Join Date
    Aug 2009
    Sydney, north


    Hi Joey, please use this site's image uploader for your pics.

  4. #4
    Senior Member
    Join Date
    Oct 2017
    Melbourne - Yarra Ranges


    ...how were they going to do the pour? - lay and additional 75 to 100mm on top of the old slab?
    Would be good to see the photo's.
    Is it an option to jack hammer the old stuff up....it might may have been so poorly layed there may no even be reo installed??

    For reference, if they were to do a proper job, it would be
    -...need to determine of the old stuff is structurally sound, if yes then:
    - 3 to 4 sheets of reo F72 (depending on your floor dimensions and how the reo needs to be cut and over layed 200mm to 300mm)
    - bar chairs (25/40's) to ensure the reo is sitting in the middle of the slab
    - forms
    - possibly a coat of concrete bonding agent applied over the old stuff
    - 3 to 4 cubes of concrete

    Approx - $1500 in materials (listed) + others as required
    + labour - setup, barrow in concrete, concrete finish, packup

    all said and done, price sounds about right depending on the amount of setup/prep work required.

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