The previous owner of our home increased the area of a small concrete patio by having an ~18-in wide L-shaped extension poured around the two sides not in contact with the house. I now want to put composite tiles from NewTechWood as a floating deck on top of the patio, but the problem is that one end of the extension sunk when I had my grill sitting on it and we had a ton of rain. The extension is now about 1/2-in below being level with the rest of the patio at its deepest (see attached photo), and it gradually inclines back up to be level (the extension cracked as it sank so it looks like the rest of it after the crack is still level with the patio). Experimenting with the deck tiles (which are 1-ft square and snap together at the edges) shows that the ones near the end of the extension (where it has the biggest height difference with the patio) will be too wobbly if someone steps on it. So I'm looking for advice on what I can do to bring up the height of the extension to level with the rest of the patio. I was thinking I might be able to make a form and layer concrete patch to level it out, but I'm not sure if that's really feasible. Any advise is appreciated!

 

It is very difficult to get a thin skim of concrete to stick long term. I would rent a concrete grinder and grind down the higher concrete.

 

So before any discussion regarding the solution to fix the uneven height, what caused the problem and what has been done to resolve???

 

@Marq1, my assumption is that the extension sunk due to a combination of the weight of a large grill and excessive rain which caused the ground underneath to soften to the point that the concrete was pushed down. I've moved the grill to another part of the patio and haven't seen any issues since.

 

@Pilot Dane, but then that would create a slope in the patio given not all of the extension sank. I'm also concerned about how long a thin bit of concrete will last, but since it's going to be covered by the floating deck tiles, it's probably the lowest effort remediation to try at first. When I was at the home improvement store, I actually spoke with a fellow who is a concrete and paving contractor, explained what I was trying to do, and he recommended a product that he felt had a good chance of adhering. If it doesn't work, I can always disassemble the deck tiles (they just snap together) and try something else. Thanks for the response.