How do you repair these sinking sidewalks?

[John Kogel]

Same problem, two 50's houses, the perimeter drains have been dug up and replaced. New sidewalks were poured. The soft disturbed ground at the perimeters sank, so now the sidewalks are dumping rainwater against the foundation.

I know the downspout needs to be changed in the first pic.

Has anyone here repaired this problem?

Did you simply pour new concrete on top?

Break up the old concrete first?

Try to raise the slabs individually, and prop them up?

Mud jacking?

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[Charlie R]

I've only seen one case where they poured over the existing, and then the whole mess continued to sink. Might make some saw cuts and then try mud-jacking, probably just as cheap to crack it all out and replace. My own sidewalk got undermined by the "oh, don't bother the cute little chipmunks!" and now I'm looking at the same issue.

[Erby]

I'd get bids for mud jacking and total replacement. Go with whichever is more economical.

[Les]

That seems to be the ideal condition to recommend mud-jacking. I have a fair amount of experience with mud-jacking and am a believer.

[allseason]

I have one experience with mud jacking, my brother had a patio that settled near the foundation, builder mud jacked, patio sank again. That was Chicago area with apparently loose soil.

How about remove, install controlled fill, gravel and then the concrete. Put some pitch on it to compensate.

[hausdok]

The contractor failed to properly compact that backfill in lifts and now he's going to have to pay the piper, either by redoing it or by paying to have it mud-jacked back to proper plane. It'd be quicker to remove the slab, compact the hell out of it and then place a slab. If not, they should probably give that soil more time to reach final compaction before they try to mudjack it or it's liable to keep settling.

ONE TEAM - ONE FIGHT!!!

Mike

[Marc]

I dunno if I'd want to recommend mud jacking on this one. Not to bash it, just that there might be leaks in that new drain that has created large cavities beneath the sidewalk. I'd want to address any such possible leaks in my recommendation.

Marc

[hausdok]

Good point,

I've had a few cases where a "compent" contractor had replaced the old concrete crocks and downspout drains around homes with perforated plastic drain pipe and then sworn up and down that his new foundation soaker system was not the cause of the settling flatwork and the water in the crawlspace.

Did you check those downspout receivers to see what kind of pipe they'd used?

ONE TEAM - ONE FIGHT!!!

Mike

[gpdewitt]

There are other issues here to address. In at least one picture, stucco appears to be touching concrete. Allseason mentioned pitch, as I'm sure you know, these slabs MUST pitch away from the building. 2" clearance between stucco and concrete must be maintained. Once settlement problem is handled (considerable depth of road base under new slabs?) grading and possibly additional drainage system will be required.

[blindrid]

I'd get bids for mud jacking and total replacement. Go with whichever is more economical.

Agree 100%.

[Brimar]

Another thought is using a poly-mor method. It is very similar to mud jacking but uses a polymer base instead of concrete slurry.

Check out the link

http://www.poly-mor.ca/VE/index2.html

[John Kogel]

Thanks to all. Good advice I can pass on.

The new drain pipes are 3 and 4 " solid plastic. But for some reason on that one house, pic 1, they let that one downspout dump right there. [:-dunce] All the runoff from a large roof area, addition, runs out there. That's a leak under the slab, for sure.

And yes, the sidewalk comes up too close to the stucco on pic 2.

[Garet]

Slab replacement and mud-jacking both address only the symptom, not the problem. The problem is the deeper loose soils. Unless the loose soils are excavated and replaced the surface will continue to settle and it may need to be repaired again in the future. The good news is that the rate of settlement slows down over time. The bad news is that there's no way to predict if it will settle again.