Extension slab is higher than existing slab

Hi All,

We had our concrete slab poured for the extension a little while ago and all looked great till we remove all the framing of the existing external wall. Once we did this we noticed a lip about 5mm or so. It looks like the laser level may of been out 5mm when they poured the slab.

5mm is not noticeable if you are tiling, however we are going to lay bamboo which only has a 3mm underlay. So this means that the 5mm gap will affect our flooring.

Has anyone else had this problem, do you need to get the concrete floor grinded, so it 'feathers' down to the existing slab or is there another method? I had a guy come around the other day and he said that we need to grind it but also get it screeded, this doesn't make sense to me.

Where I have seen this problem on commercial sites, a levelling compound is applied to the lower floor.

is it possible its just higher on the edge? Therefore you may be abel to grind it down?

its most likely that where they took the height off the original slab was higher than the edge you were joining into.

I almost got caught once where the only place we could shoot a level too on the existing slab was 40mm lower than the edge we were joining onto.

5mm is not much,grind the high part down about 3mm on the edge and feather it back to nothing over about a meter, then as suggested above use a leveling compound and fill along the low part.