Depth of Concrete for SLAB

[backyarder]

Hi, I'm building a 4m X 4m single skin block outbuilding at back of garden.

I've compressed about 5m * 5M of hardcore 50 cm deep. 2 questions:

1) How much depth of sand do i need to compress on top of this
2) I'll place dp membrane over this and concrete above right?
3) how much/deep should the concrete be? 50 cm deep?

I live in Essex (clay).

Any help much appreciated - thanks.

 

[stephenf8542]

is this including your foundations?

 

[backyarder]

this is my foundation - a simple slab - didn't think i needed much more for a single skin block wall?

 

[stephenf8542]

what kind of out building is it?

 

[noseall]

Dig a footing, lay masonry up to dpc, then lay a membrane with the floor slab within.

You end up with a damp floor if you use the slab as a foundation and it is a pants way to build anyhow.

 

[backyarder]

It's for an office - basically a desk, computer and a few books - i didn't want to go down the footing route because its clay plus a few trees within 5 meteres, thought a slab would suffice seeing as it's a one block thick building....

so guys anyone able to help with depth of concrete and sand required?

 

[stephenf8542]

The frost heave will move it

 

[Alastairreid]

It's for an office - basically a desk, computer and a few books - i didn't want to go down the footing route because its clay plus a few trees within 5 meteres, thought a slab would suffice seeing as it's a one block thick building....

so guys anyone able to help with depth of concrete and sand required?

25mm sand blinding
1200 guage dpm
100mm c35 concrete.

 

[backyarder]

thanks

 

[Shytalkz]

The frost heave will move it

And how will that happen?

 

[richjamesw]

some mesh in the concrete maybe an idea

 

[backyarder]

some mesh in the concrete maybe an idea

definately intend to put mesh in.

 

[wolfman1]

I see the reason for building this way, technically not correct, but will do, i have a garage built on a slab and had no problems, at least if the ground moves the whole slab tends to, i would reinforce it and probably dig the edges a bit deeper to suport the weight of the wall.

 

[richjamesw]

a raft foundation basically