Concrete steps sinking - best way to fix? (1 Viewer)

[e9999]

I have several flights of steps that are concrete. These are just 2 or 3 steps from the ground level to doors of the house. Solid concrete I think, some with mexican style tiles on top. The steps are not connected to the house but unfortunately some are connected to outside concrete pads further outside. Over the last 30 years or so, all those steps have started to sink a bit into the ground. Most by 4 to 6". So they are now slanted inwards towards the house. Some have cracked or cracked the attached pad. Depth towards the house is something like 4 to 5'. Width (parallel to wall) ranges from 6 to 20'. Height above the ground 2 to 3'. I imagine we are talking many thousands of lbs each.
So I will need to lift those back up and keep them there. This does not seem trivial. Of course I'm contemplating Portapower type devices to lift things but I likely should also think about the underlayment and reinforce/rebuild that so it does not sink again later on. That would not be easy for the big ones.

So, any suggestion on what techniques to research here? I remember seeing some vids of people lifting driveway bits with foam. Is that a realistic option?

 

[micruz60]

You may have suffered the settlement of backfill that was not adequately placed and compacted.
One solution would be to enlist a concrete contractor that is skilled in placing hydraulic grout underneath to raise the steps, this may or may not work. . . the grout will flow wherever there is no resistance.
You could also drill into the top of the steps with allthread / coupler to an eyebolt and raise them with a porta-power /hoist and then inject the concrete grout into the void below, then after the concrete sets up, you remove the hoist / allthread and move on.
The proper way to do the steps is to initially put rebar dowels into the foundation wall before placing the concrete for the steps, that way the steps are anchored to the house, and this avoids the differential settlement.
Where the slabs are cracked adjacent to the steps, it may be best to sawcut out the failed slabs and place new concrete.
HTH

 

[e9999]

thanks. Unfortunately, I think it would be quite hard to lift the steps with an abovehead hoist, some steps are quite wide so the span of a gantry would be too much, and the floors inside are just wood on joists, so not very strong. I may have to do it with lifting hydraulic jacks on the ground. For the narrower ones, maybe a couple of hydraulic jacks on the sides and then inject some sand under the steps? But the 20 footer, yikes...

 

[micruz60]

Yeah, the twenty foot wide one is a toughie, you could drill several holes with a masonry bit / hammer drill at the center 10' / 6' each side and inject the hydraulic grout there? That would be a long drill bit. . . Who knows, maybe consult with a house mover?

 

[WarDamnEagle]

Those might be solid but typically they are not. You normally build a frame and fill it in partially with backfill or sand and then pour concrete over the filler. I think the only way to get it right is to bust them out and pour new ones. Some pics would help.

 

[e9999]

good point, they may be less than fully solid throughout. And yes the thought crossed my mind that trying to raise them if super heavy may be more trouble than building something new, maybe out of wood, which would be fun to do. (Don't know much about concrete TBH.)

So, there is no magic solution with drilling a small hole and injecting something to lift the whole thing, then? Dang...

 

[PIP]

I've only done a few hundred yards of flatwork and a few mid sized jobs that had complex forms, but my take on concrete is it's usually easier to start over with the correct approach rather than try to fix something.

I would use a small excavator with a hammer to remove all the old steps, excavate the subgrade and fix it right.

Are there any drainage issues? If so, make sure you fix the water problems as part of the step repairs. Most soil is good for 1000+ PSF no problem, but add lots of water and that number drops to nothing.

 

[fjc-man]

Get a quote or two from a couple “Mud jacking” companies. You might be surprised what they can do.

 

[bkfj40]

We have switched to specifying raising them with pressure injected foam as most of the mud jackers in this area of Virginia have dried up.

Part of the issue is the lack of compaction of the full as noted above as well as not pinning them into the structure.

You can also use helical piers, but by the time you do that, the cost is gonna be close to tear out and replace

Good luck! Keep in mind, you will get the money back out of it at sale time.

 

[e9999]

it's pretty impressive actually what they can do with polyurethane foam (well at least from what I see on Youtube, have not seen it firsthand). It's tempting but not a DIY solution I'm afraid, and I'm sure it's pretty costly. But may end up doing that.

 

[PAToyota]

I'm seeing the changeover from "mudjacking" to foam around here too. Major benefit is that the foam doesn't weigh nearly as much and doesn't just lead to more settlement due to the increased weight.

If the steps are otherwise in good shape, I'd at least call the foam guys (if you can find them in your area) to see their thoughts and costs. As others say, it's likely going to be a wash between "saving" and just replacing them with new. Without seeing the specific situation, it's hard to armchair quarterback the solution over the 'net. I do agree it is likely settlement of the backfill around the foundation and that it is unlikely you're going to get a DIY solution to save the existing steps that is going to be effective other than to break it up and place new concrete yourself.

 

[e9999]

yes, I'm afraid that any pro intervention may not be big savings over new although would save time and aggravation I think. Aanother benefit in general of the foam is the low risk of any of it being washed away by water compared to mud, I believe, but in my case that's not a big problem either way TBH.

 

[fjc-man]

It’s actually a mortar slurry that sets up.

 

[e9999]

Sure and I hope that is true in most cases but I've also read of material used that can be eventually washed off by water. Probably cutting corners I guess.