Sink in yard. Red flag?

5 years ago

Hello,
I recently bought a new build and there was a sizeable hole under the sod (about the size of a basketball), a few feet from the house. We didn't think much of it initially (figured maybe a nest or a huge rock had been removed from the area). However, when we installed our patio, we dug and filled back with gravel and compacted multiple times. Literally, a few weeks later, there was an obvious dip in that area that has slowly grown wider over 3 months. Should we be worried. What can cause this?

Featured Answer

fnmroberts

5 years ago

HU-32873516 -

You don’t mention where you reside and/or IF your new home has a basement or crawl space. Generally the excavstion for a foundation extends beyond the house about 4 feet. Depen Depending on your freeze/thaw cycle, it can take 5 or more years to completely settle. You mentioned compacting however there could be a void deep in the backfill. Just speculation.

I like patios too but I would’t recommend one ever be built over backfill for at least 3 years - leave that space as planting beds.

Just specilation on my part and hopefully your issue resolves itself.

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Comments (7)

fnmroberts
5 years ago
Most likely it’s the backfill settling around the foundation. This can take several years. Your patio installer did you no favors - be ought to have discussed the situation with you.
HU-32873516
Original Author
5 years ago
Thanks for responding, fnmroberts. We installed the patio ourselves, with expectation that it will settle over time. We can pull out the area and fix it later if it gets deeper. Right now, it a relatively minor undulation. I was just concerned that it was in the same spot that we had noticed the hole pre-patio. Could there be a reason the same spot keep "caving" in?
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HU-32873516
Original Author
5 years ago
So, my husband was explaining the backfill more to me. I should add that the ground is clay with a LOT of medium to large rocks/boulders. The developer leveled and graded before laying sod at the beginning of winter, yet our lawn was uneven to walk on when we took the kids out to play in the spring, so I imaging the settling is uneven due to all the rocks. This "hole" is about 14ft from the foundation of our home. I guess I'm wondering what the likelihood of this being a never ending "sink" is.
3onthetree
5 years ago
By the title, I thought you meant literal sink. Like kitchen. Insert Indiana joke here.

The top of the overdig for the foundation is usually about 5' away from the wall. If there is one spot, like a "sinkhole" more than just gradual settling of the whole area, then there could have been a tree there. If it was an old farm field, it could have field tiles still down there. The builder could have thrown a large chunk of concrete in the backfill (from demo or the wash) that has a pocket around it. Worst case scenario would be if you have your water entrance or sewer/septic going out through there. I would monitor over then next 2 years unless it's real bad.
HU-32873516 thanked 3onthetree
HU-32873516
Original Author
5 years ago
@fnmroberts we're close to the DC area and the home does have a basement.

@3onthetree lol. Reading I title again, I can see it.

I saw the land before construction and there wasn't a tree but I don't know what it was used for before e development.

We keep an eye on it over the next couple years and hopefully, it resolves itself.

Thanks for your input.
di0spyr0s
4 years ago
One cause of localized sinking can be running water underground. If the sink is anywhere near your water lines I would get them checked for leaks.