Ballast quantities, Concreting, shed base,

Discussion in 'Landscaping and Outdoors' started by scottb005, Jun 7, 2020.

  1. scottb005

    scottb005 New Member

    So I've been digging an area out for a shed/ summer house base and trying to get a decent idea for the required material is a nightmare.

    Many sites gave my a rough idea but this figure varied between 3.5 - 5.8 bags of ballast.

    So I'm going to explain my situation and hopefully you can work out roughly whats required. This is what happened.

    Area: 7m x 3.3m x 100mm
    Volume: 2.34 meters3

    I ordered: 3 x Bulk Bags of Ballast (800kg Bulk)
    39x Bags of 25kg bag of cement.

    For a 13 cement per bulk bag of ballast (advice found on B&Q website)

    I filled half the area using 3 x bulk bags of ballast & 17 bags of cement.

    So... I actually needed: 6 x Bulk Bags of Ballast (800kg Bulk)
    34x Bags of 25kg of cement.

    I would advise to slightly over order on cement just incase you use more in each shovel load.
    BUT, by way of ballast, 6 bulk bags is a definite for that area.

    So thats 4.8 Tonnes of ballast to fill an area of 2.34 m3.
    850 kg of cement.
    5650 kg (5.65 Tonne) of material total.

    I hope that all makes sense. Do the math yourself, but I will be going off 2.3 Tonnes of Ballast for every 1m3.

  2. scottb005

    scottb005 New Member

  3. AnotherTopJob

    AnotherTopJob Screwfix Select

    I'm not sure but our neighbour has done a couple of bases recently and it was cheaper to have a lorry deliver readymix and wait while they barrowed it down their long garden.
    scottb005 likes this.
  4. stevie22

    stevie22 Screwfix Select

    I'm not quite clear what you're trying to say here. The normal density taken for concrete is 2400kg/*** and 6 : 1 is a good mix to use so it's not really rocket science. When you ask the same question and get such a wide variance as you have then more research is needed.

    That steel is pretty much useless by the way: you should have used mesh.
    scottb005 likes this.
  5. rizzoeve

    rizzoeve New Member

    Hi, I'd recommend a quick "aggregate calculator" search on Google. Input the dimensions (length, width, depth), they're never far wrong. Also "Paving expert" (again a Google search) has lots of really good advice, easy to understand instructions, calculators, etc (If you're not familiar with this area. I really recommend taking a look).
    scottb005 likes this.
  6. scottb005

    scottb005 New Member

    I understand its not rocket science but nowhere online gave me the correct amount required and as I'm just a normal bloke giving it ago I didn't know the ratios. even with much research online, there was never a sold figure.

    also, the steel was given to me by a friend, more of a bonus, I wasn't ever planning on using any. But I agree, mesh would have been better.
  7. scottb005

    scottb005 New Member

    Hi, thanks. I used both of those and many more and never got 2 of the same answers. So just went with my gut feeling with the expectation of doing it in 2 loads and not over ordering.
  8. scottb005

    scottb005 New Member

    Agreed, it would have worked out the same cost in the end. I wasn't expecting to have to order more ballast.
    Lesson learnt ready for the house extension.

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