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patio falls and layers

Discussion in 'In the Garden' started by zuber ali, 20 Aug 2021.

  1. zuber ali

    zuber ali

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    Hi All,

    laying some porcelain slabs in my garden. I have read its best to first allow for the fall when I'm laying my hardcore, rather than doing this only when i lay the bed as this reduces the amount of material you need to use to make a fall, but this doesn't seem to make sense to me as if the soil layer beneath the hardcore has not been dug out to the correct fall you would end up having thinner layers of hardcore on one end?

    am i correct to assume i should actually get the soil layer first to the correct fall, rather than leaving this flat and adding a fall only to the hardcore/slab layers

    thanks
     
  2. Bonni

    Bonni

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    First step, dig out. Then you need to whack in 3 to 4 inch of hardcore. Then lay down 3 to 4 inch of weak mix concrete. Then full bed porcelain tiles on 3:1 mortar 25mm to 40mm thick. Pick a fall from the house and as long as it falls away, place a string line and bed the tiles.

    So, you need to take the tile thickness, bed thickness, concrete thickness and hardcore thickness into to account to dig out. Even if the fall is 5mm over the entire patio, the water will flow away from the house.
     
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  4. JohnD

    JohnD

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    And I'd add, before you start digging, find the DPC.

    your finished height should be two bricks below (or more)

    very often you will find some numbskull has already laid paving that raises the ground above the correct level, so you need to reduce it, to reduce damp problems.

    Have a good look at any drains or gullies while you are digging. If they are in brown-glazed fired clay, they are likely to be cracked and leaking.
     
  5. John D v2.0

    John D v2.0

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    as long as you don't exceed the maximum thickness per layer of hardcore when compacting, you can put in as much as you like within reason to make up the correct levels. You should also dig out any weak spots. e.g. In our drive there were roots from the street tree snaking around underneath, we dug them out and filled in those areas with extra hardcore, so the thicknesses were all over the place 100-250mm, but it didn't cause an issue as it was all well compacted.
    the bedding layer above the hardcore needs to be even thickness, but it sounds that is your plan already.
     
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