# Ballast quantities, Concreting, shed base,

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

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1. ### scottb005New 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.

3. ### AnotherTopJobScrewfix 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.

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4. ### stevie22Screwfix 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.

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5. ### rizzoeveNew 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).

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6. ### scottb005New 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. ### scottb005New 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. ### scottb005New 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.