John wrote:

I need to lay a concrete base for a shed. I recall needing a mixture of
ballast and cement, but need help in

Why concrete?
A layer of slabs on a light mortar base would be far easier to lay, as
well as being very easy to take up if you ever want to move the shed.

The shed size will be 10ft x 6ft.
I'm asuming the base will be around 6 inches deep (unless you guys advise
otherwise).

6" deep?
How many tons are you expecting the shed to weigh?
I'd say a 3" layer of cement would be sufficient for any garden shed, if
the sub surface has been flattened/compacted.

Rough calcualtion - 10'x6' = 6 sq. M. , x 75mm depth = .45 cu M.
x 150depth = .9 sq. M.
A bulk bag of ballast will be roughly 850kgs (they are a nominal 1
tonne, but dont come very close IME.)
A bulk bag is roughly .75 Cu.M
A 10-1 mix would be fine for a shed I'd say, though for a harder surface
go to 6-1. So at 10-1, you need 85kg of cement, at 6-1, 140kg to mix
with 850kg of ballast.
850kg would give a depth of 4 to 5 inches.

Alan.
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