I have a home that is 2 years old. I found the ground settling under the concrete slab for my paver patio in one corner. About 2-3 inches gap that goes deep in. It hasn’t sunk or cracked. It’s being held up because concrete slab is pinned to the foundation on 2 sides of the rectangle shape patio.

What is the best way to fill the gap and with what materials?

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  • Hello, and welcome to Stack Exchange. Another picture, showing where the ground slopes away, might help us find a good solution for you. – Daniel Griscom Sep 1 '18 at 20:26

Any inorganic gravel or sand will do the job. The trick is packing it in tightly enough to eliminate all gap. As you can imagine, concrete doesn't flex, and any gap will eventually result in a crack and settling of the concrete.

Fill the gap by tamping horizontally with a piece of lumber or similar tool, and work your way out. A little bit of moisture might help compact things as you work. Once you have the void completely filled, landscape around the patio to retain the material you've installed. This is critical to long-term success.

You may need to hire a "mud jacking" company to inject concrete through the slab to fill the void where it's inaccessible. They'll drill small holes and patch them when they're done.

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  • Thanks for the comment. One problem I will run into is the patio was set up where 2 sides of the rectangle shape patio is attached to the house. I won’t have access to fill in the gaps on that corner. – user89197 Sep 1 '18 at 13:01

I would suspect erosion rather than settling. As the first attempt to resolve the problem fill with soil and tamp it medium. If you can get a small amount of weed free sod of the same type as your lawn, cover it with that, otherwise seed it.

Observe the flow of water during a rain. You may have to fill with rocks. Smooth "river rock" looks better than crushed rock and is much easier on feet (humans and dogs), but is more expensive. River rock is safer for a kid taking a tumble on it.

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  • Thanks Jim. I checked the other corner and it looks like there is a gap too. On the outside, you’re seeing a mulch bed around the house so I’m not worried about the outer part of the patio. I read gravel might work to tamp in? – user89197 Sep 1 '18 at 10:52
  • If it is settling, then you will be able to fill it with soil and that will be that. As @isherwood wrote you want to support the concrete so it won't crack. – Jim Stewart Sep 1 '18 at 14:29

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