Red-neck mudjacking?

[Jim Elbrecht]

A couple years ago I had to dig up my foundation, and despite our best efforts at machine tamping to 'refusal'- it apparently wasn't enough.

So now the slab for my oil barrel is pitched 1/2 inch towards the house. If it went the other way, I'd just watch it-- but I'd like to correct it as it is bound to get worse. The slab is 3-4"thick and

3'x6'.

I can lift the slab at the two low corners and get it back to level- and will pitch it away from the house. But what is the best way to try to get a slurry under as much of the slab as possible.

My first thoughts are to;

1. make roughly 8" square access holes a foot deep on the 2 low corners -
2. jack to level-
3. enclose the 'piers' and most of the back side - leaving a space in the center.
4. fill with a loose slurry until it begins to ooze from the center.

I have access to a concrete vibrator- but I have only seen one in use once and I'm not sure if it will work here.

What are my chances that this will keep this slab more-or-less in place for a few more years? [I'm in NY- btw- so frost will guarantee that it will never stay exactly where I put it- I'm just trying to get it to be 'off' in the right direction.]

Thanks, Jim

[Abe]

Any chance you could make the jacks permanent and adjust them as needed?

[Pete C.]

If it's the usual 275-330 gal tank with pipe legs, just get four of the standard scaffold screw jacks and some suitable washers and install them into the pipe legs so you can just adjust them as needed and not care if the slab is a little out of level.

[Bob F]

I just leveled a concrete hot tub/spa. I jacked it up, then pumped fairly fluid grout under it using a hand powered grout pump I bought second hand. I connected the pump output to 3/4" pvc pipe and slipped that under the slab, built a wall around the edge, and pumped until it came back out, and then some.

Bob

[KC]

I've seen them level a sinking corner of an office building slab by underdigging down about 24", pour a small 4" slab, let it dry, insert several jacks between the new & old slabs, get the old slab level, then fill the whole thing with concrete leaving the jacks imbedded in the concrete. A real red-neck fix but it worked.

KC

[Jim Elbrecht]

-snip-

I considered that- but it will leave me with a much smaller footprint that is more likely to sink again. By filling the air gap with grout/mortar, I at least stand a chance that I might not have to do this job again. [or so I hope]

Thanks-

Jim

[Jim Elbrecht]

-snip-

I don't mind the slight out of level as much as I don't like it dumping the runoff towards my house. There is about a foot gap- but it just isn't a good place to have extra water.

If the slab was pitched away from the house I'd be getting 2 screw jacks.

Thanks- Jim

[Jim Elbrecht]

-snip-

Super! I looked at them on ebay--- think I'll call a rental place thursday. They seem pretty dear for a simple pump. [$500 for a

5gallon- no used ones today]

Hmmm- - same brother-in-law who has the vibrator might have one in his barn.

Good idea- thanks. Jim

[Jim Elbrecht]

-snip-

I'm making a much smaller hole- and trading out my jack for a chunk of galvanized pipe- but in general that's my plan.

Now to find that grout pump. . . .

Jim

[Bob F]

It'll be interesting if you find a rental. I couldn't in Seattle. So I went for the one on craigslist.

Bob

[Jim Yanik]

KC wrote in news: [e-mail]:

To raise your slab,drill holes for expansion anchors,place bridging beams (4x4s)across the slab with holes drilled for threaded rods that screw into the anchors,and put washers and nuts on the other end of the threaded rods.Tighten the nuts to raise the slab. Then you can pour some concrete slurry under the slab to keep it up.