How do I replace this concrete slab?

[Heversham]

Hi all,

I have a problem I’ve been puzzling over for weeks and could do with a steer on.

I want to pave over this concrete slab with stone flags. The slab is suspended over part of the cellar. It replaced a skylight that let light into the cellar.

It’s 150mm thick, sitting on a wire mesh, which you can see in the picture I took from the cellar, looking up at the underside of the pad. The span is about 3ft. When it rains, water leaks around the edges of the pad into the cellar.

I want to lay stone flags here, as this will become the front door. The concrete is flush with the interior floor level, so it will either have to come out or the height will need to be reduced. I also want to stop the water ingress.

There is a gas pipe running through the far edge of the slab, which comes out in the cellar below.

I’m unsure of the best way to tackle this. I can’t see it’s possible to remove enough concrete to allow for flags and a mortar bed.

I could remove the whole thing and lay a new pad, but how do I suspend it?

Also wondered about using concrete gravel boards as a substitute pad. They’re reinforced, and I could add concrete beam/RSJ offcut below to support the span in the middle.

But I don’t know if this will work! Or how to stop water from getting round the edges and into the cellar.

Any advice gratefully received.
Thanks!

 

[Notch7]

I could remove the whole thing and lay a new pad, but how do I suspend it?

concrete lintels

 

[Heversham]

Would they break under the load? I thought lintels were supposed to support a distributed load. But if they would work, that's a great idea.

 

[noseall]

Would they break under the load? I thought lintels were supposed to support a distributed load. But if they would work, that's a great idea.

The smaller section ones require a composite load (brickwork/blockwork coursing) above - correct.

Notch probably meant a two course (140mm deep) brute.

 

[Heversham]

Makes sense. I think the 140mm lintel would be too deep - the existing slab is 150mm deep, and I'd need to allow for the flags and bedding course.

What about using something like the mesh that's already there? I can't seem to find an equivalent, but maybe I'm looking for the wrong thing.