Concrete Base

[Mushty]

Hi, I'm looking to replace and old 10 x 8ft shed with a larger 10 x 12ft one.

I'll need to extend the current base on one side to accommodate it but have also found that it gradually drops away into one corner on this side up to about 50mm (other than that in good condition). It's one complete slab and there's no sign of any cracking so may possibly have been laid like this. For the new section I'll dig out, whack down a sub-base and then thinking of laying new concrete but also carry on across and resurface the existing slab to level it all up.

Question really is what's an acceptable minimum depth of concrete I can go with over the level area of the existing slab?

Any advice much appreciated.

 

[Terrywookfit]

That would depend on how level it is.

How thick is existing base at edge. Drill it in various places to gauge thickness in middle.

If it is just a Shed loadbearing will be minimal.

 

[Mushty]

Thanks for the reply Terry - it's around 4in of concrete + sub-base, I've put a level along the front and down one side and it's fairly plumb, just starts tapering away from around the centre to one corner where it gradually tapers off to a 50mm drop from the good corner to the bad one. If I lay the new concrete section and carry it on over to resurface the rest, just wondering what depth of concrete I'd get away with on top of the existing level part of the slab?

 

[Terrywookfit]

A couple of inches over existing. I would use a smaller aggregate in the mix.

 

[Mushty]

Cheers, appreciate the advice.