There are two ways to look at it Steve; Either the slab will need to be strong enough to support the whole structure on the slab edges without it cracking, or you can lay proper foundations for the dwarf walls (which will then bear the weight) and later pour a thinner layer as the floor within those walls. Personally I'd go for the latter as you can then tackle this yourself in sections. If you choose the former, you will need all of the concrete pouring in one go, which probably means getting professionals in or hiring a fairly large concrete mixer and having a lot of space nearby to store all of the materials for the mix.
A trowel in the hand is worth a thousand lost under a bush.
There's no single answer to that - depends on the weight being supported and the type of ground you have. Digging a 15cm foundation and filling with hardcore as a base (and then compacted), with a 15cm layer of concrete on top of that would be more than sufficient for such a slab supporting a single story wood and glass structure I would think. That's what I used as a foundation for my conservatory.
A trowel in the hand is worth a thousand lost under a bush.
Steve - your structure is going to be timber and glass? The specifications Bob has suggested should be plenty strong enough. I've got a dog kennel at the bottom of the garden,a pretty hefty one with a run and metal bars etc. And that's just laid on 2ft slabs with sharp sand underneath. Its been there for 8 years and hasn't moved an inch.
If you want the structure raised,you could have a single concrete 'slab' of maybe 100mm. Using some lengths of timber as shuttering,you could order ready-mix concrete and pour it in one go as long as you have some help on hand to shovel and tamp the concrete. That would do away with the need for brickwork but it depends how much higher you want the floor than the surrounding ground
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There's another thread going about shed/greenhouse bases.
It's on Tools and Techniques.
There are two ways to look at it Steve; Either the slab will need to be strong enough to support the whole structure on the slab edges without it cracking, or you can lay proper foundations for the dwarf walls (which will then bear the weight) and later pour a thinner layer as the floor within those walls. Personally I'd go for the latter as you can then tackle this yourself in sections. If you choose the former, you will need all of the concrete pouring in one go, which probably means getting professionals in or hiring a fairly large concrete mixer and having a lot of space nearby to store all of the materials for the mix.
There's no single answer to that - depends on the weight being supported and the type of ground you have. Digging a 15cm foundation and filling with hardcore as a base (and then compacted), with a 15cm layer of concrete on top of that would be more than sufficient for such a slab supporting a single story wood and glass structure I would think. That's what I used as a foundation for my conservatory.
I was assuming that around 15-18cm with a bit of hardcore at the bottom would be OK.
Steve - your structure is going to be timber and glass? The specifications Bob has suggested should be plenty strong enough. I've got a dog kennel at the bottom of the garden,a pretty hefty one with a run and metal bars etc. And that's just laid on 2ft slabs with sharp sand underneath. Its been there for 8 years and hasn't moved an inch.
If you want the structure raised,you could have a single concrete 'slab' of maybe 100mm. Using some lengths of timber as shuttering,you could order ready-mix concrete and pour it in one go as long as you have some help on hand to shovel and tamp the concrete. That would do away with the need for brickwork but it depends how much higher you want the floor than the surrounding ground