Walls built off concrete slab - possible to replace slab?

[CortinaV8]

My detached garage was originally a single, with conventional foundations for the walls. At some point in the 1980's the garage was doubled in size, a slab was cast next to it, the walls were built directly off the slab and tied into the original structure.

Both slabs are now cracked in various places, probably from the shrubs the previous owner planted around the garage and let get out of control.

I'm wanting to replace the slabs but suspect this is not going to be possible on the newer section? I've no real issue with getting the walls on the new bit rebuilt (I'm replacing the roof also) but would obviously rather not if there is another option?

 

[^woody^]

You would need to underpin the perimeter in stages.

But a cracked slab does not mean that they have failed and need replacing.

 

[CortinaV8]

I don't believe the slab has moved in my time of ownership, and nothing new has developed. The main reason for wanting to redo the slab is the old portion of the garage looks like it was finished with an artexing trowel.

I also wasn't sure if adding anything on top of the existing slab would be wise as I use the garage for working on vehicles (engine crane, jacks etc) and wasn't sure if would hold up to this?

 

[mfarrow]

Some nice commercial floor tiles should do the trick, like these: http://www.directtilewarehouse.com/...commercial-floor-tiles-anti-slip-floor-tiles/

 

[^woody^]

I don't believe the slab has moved in my time of ownership, and nothing new has developed. The main reason for wanting to redo the slab is the old portion of the garage looks like it was finished with an artexing trowel.

I also wasn't sure if adding anything on top of the existing slab would be wise as I use the garage for working on vehicles (engine crane, jacks etc) and wasn't sure if would hold up to this?

It's the slab thickness and what is underneath the slab that matters. Putting something on top won't make a difference to is load bearing capacity.

A 100 mm slab will take any vehicle repair loads, and if the slab was going to sink as it would have done so by now.

Finish the surface by grinding flat, or lay an epoxy cement coat and floor paint.