Laying concrete garage floor - advice please

Discussion in 'Builders' Talk' started by Chris Berry, Jul 13, 2018.

  1. Chris Berry

    Chris Berry New Member

    I have laid a bit of concrete in my time, but this job is a bit different.

    I have just re-roofed an old garage/outbuilding. It is about 6.5m by 6m internally and has an old concrete floor that is sloping by about 2 inches over the width. The concrete is about 6 inches thick and in reasonable condition. I want to pour a new concrete floor slab on top of the old one to raise the floor level by 4inches at the highest point and 6 inches at the lowest.

    Should I use a DPC on the existing floor and pour on that or should I bond directly to the old floor and what preparation would I need. Do I need reinforcing in the slab? Would you try and pour in one go or divide floor into sections?

    Any other advice appreciated too.

    Thanks in advance.
  2. jonathanc

    jonathanc Active Member

    Dig out a bit of your existing floor to see if a doc is present. If yes then pour on top. Just make sure you don’t bridge the dpc in the walls.

    Don’t think you need reinforcement unless u putting a two post lift in.....
  3. Isitreally

    Isitreally Well-Known Member

    Is the existing floor dry ???

    If so theres no reason why putting another layer on top will suddenly make it wet.

    Weirdly enough though you should wet it before you pour the new concrete, this will help it bond by not drying out to quickly.

    I would split it into section to pour it if it was mine making it easier to do.
  4. Chris Berry

    Chris Berry New Member

    There is no existing dpc and while it doesn't get wet, there is some moisture in it over Winter e.g. you can't leave paper or the likes on the floor for too long. I think doing it in sections makes sense and will make it more manageable.

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