Slab sinking

[Missionstreet]

I have a relatively new concrete slab that is about 23 by 13'. It is built on a bit of a grade with coordinated drainage pipe underneath.

It really is two pieces, 12x13 each. I noticed the side closer to the slope sunk about 1/4" to *gasp* 1/2" near the center where they meet after backing up into it and then changing direction again. (There is a perpenducular crack in the center to so it isn't sinking evenly)

Any thoughts?

[Missionstreet]

shelbyfv wrote:
You are lucky it's just a slab. One corner of my home foundation has sunk, as much as 1/2" depending on the season. From what I read it's going to cost $thousands to have it jacked up and stabilized. Contractors....

Haha. Actually I *think* I have that problem as well. 100+ year old brick home. Helical piers anyone?

[Missionstreet]

prichardson wrote:
What is coordinated pipe? Do you mean corrugated pipe; if so, and it is under the section that is sinking, it may have collapsed.

Actually I meant to say perforated pipe. I have looked down from the side where it comes out on the slope and looks ok. Will try my Depstech scope for more details.

[Cummins12V98]

Live with it, what is it hurting???

[azrving]

There are companies that will drill it and shoot expanding foam under it to lift it. Probably some diy people on YouTube

[deltabravo]

Missionstreet wrote:
(There is a perpenducular crack in the center to so it isn't sinking evenly)
Any thoughts?

Concrete has two guarantees, it gets hard and it cracks.

[Mfan]

The contractor I used was vdcconcrete.com. maybe $300.
Pm me if you want specific details.

[12th_Man_Fan]

The foam injection method is "Uretek " here in Texas. I had them level a carport slab several years ago and it stayed put.

Google Uretek and I bet they have a presence in your area.

Good luck.

[prichardson]

What is coordinated pipe? Do you mean corrugated pipe; if so, and it is under the section that is sinking, it may have collapsed.

[shelbyfv]

You are lucky it's just a slab. One corner of my home foundation has sunk, as much as 1/2" depending on the season. From what I read it's going to cost $thousands to have it jacked up and stabilized. Contractors....

[Missionstreet]

Mfan wrote:
I had my driveway raised by the injection method. Very happy with the result, and it was a lot cheaper than I expected.

Would you mind sharing any more details?

[Mfan]

I had my driveway raised by the injection method. Very happy with the result, and it was a lot cheaper than I expected.

[valhalla360]

A couple potential issues:
- The base wasn't well compacted and now it's compacting. As long as it stops and it isn't pooling water badly or otherwise causing problems, I would just live with it. If it gets bad or otherwise starts bothering you, yes, you can have a residential paving company come out and use injection to compensate for the sinking.
- How thick is the concrete? 4" thick and you can expect a 12x13ft flag to crack. There's a reason sidewalks typically have a 4-5ft joint spacing.
- Are there any signs of water washing away the base material? If yes, you need to stop that or it likely will continue to get worse.

[Missionstreet]

Sure a little uneven don't bother me. As long as it's not going to move enough to cause issues.

I have heard of polylevel something. I think foam injection that lifts concrete? Maybe cheaper than other alternatives?

[bucky]

Can you just live with it? It might be pretty pricey to correct.