concrete floor depth

[robworden]

Hello,
I'm new here - what a great site with loads of useful info! Hope someone might be able to help with problem I have just now:

I am just about to make good a very uneven floor in a barn I am renovating in France. I have bought a plastic membrane, sheets of 30mm extruded polystyrene to lay down as insulation, and a metal mesh.

The existing slope of the foor creates a difference of 40mm from one side to the other. Clearly, the thinner the layer of concrete over the higher part the better so as not to have excessive thickness 'down slope'. Can anyone say what is the thinnest I can safely get away with when poured over extruded poly + mesh? (I plan to put floor tiles down after it has been made good.)

The existing barn floor is concrete, sound but uneven/sloping, so after working on it the new floor will be from the base:

old uneven and sloping concrete floor, 30mm extruded poly, metal mesh, new concrete finish (depth to be determined as per guidance by somebody on the forum...please?!)

Also, anyone advise on what mix should I use?

Thanks in advance,
Rob

 

[noseall]

i personally would not lay less than 100mm, though i have seen it laid successfully at 75mm, but this was done using readymix concrete.

do you have acess to readymix or is this not practical?

 

[robworden]

Wow Noseall, that's thicker than I was anticipating. I was hoping my trusty cement mixer with trailer loads of sand and gravel would suffice but I guess I was a naive dreamer as usual.

Readymix... if you mean pre-mixed, yes it's available here but costs a king's ransom. If you mean a concrete pour delivery, yes that's available here although delivery will be expensive as we are both very remote and the barn is not easily accessible.

Any other thoughts? Anyone?