Concrete Slab mix quantities

[George_engineer]

Are you planning to construct the building off the slab or will the walls have their own footing?

150mm stone and 100mm slab with light reinforcement is what I would do. But if you want to build off the slab I would normally recommend an edge thickening (and probably required if it's masonry).

As mentioned, an outbuilding over 30m^2 is when you need to get approval.

 

[phatboy]

Minimum 150mm type 1 sub base (compacted size).

You can avoid mesh if you spend a bit more on fibre re-enforced concrete, at 150mm.

You will regret not insulating it. Sure it's not the biggest heat-loss area, but you don't want a condensation issue....