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Basement Hydraulics


Talk about a weird feeling: I stood downstairs in one of the bedrooms after the mudjacking crew had drilled six 1 3/4″ holes through the 6″ slab and down almost two feet into the soil. They stuck a hose as thick as my arm through each of the holes in turn, forcing liquid concrete into the soil. Once all the holes had gotten a dose, the hose was moved to a hole near the north wall, and the crew boss pressed the pump button once, twice, three times.

I watched as the slab rose smoothly, almost half an inch in the space of two seconds. Whoa.

It’s been a messy, dusty, ad-hoc sort of project. In summary: They drill a number of holes through the slab. (In our case it was seventeen.) They pump liquid concrete (“mud”) through a hose into the soil and/or voids under the slab. The voids fill up as the soil rises beneath the slab. Eventually, with no more voids to fill, the pressure of the liquid concrete lifts multiple tons of concrete slab back to where it was before it began to sink. The liquid concrete stabilizes the soil beneath the slab, and with some luck we won’t see the slab settle again.

There were a few weirdnesses. Here and there liquid concrete forced itself up between the slab and the stem walls (and out of a few of the holes as well) like a glistening blob in a third-shelf horror movie. The bathtub didn’t quite return to its former position and may have to be pulled and re-set.

Still, as best we can tell, the operation was a success and the patient not only survived but rose from the dead. There’s much mess down there still, with plastic taped up all over the place and my fiction and magazine stacks all boxed and inaccessible, but the flaw that precipitated the whole business has at least been dealt with. Given that we had to empty the rooms completely, we decided to pull the carpet and replace it. And with the carpet gone, there’s no reason not to re-paint. Carol has been meeting with decorators. I’m designing a new layout for the furniture. It will have been a huge amount of work (and way, way too much money!) but when we’re done, the lower level will look very good.

More on the project as it happens. The wind you heard through the pines last night, however, was a massive sigh of relief.


  1. Aki says:

    “Underpinning Project; Owners’ Views on Technology, Economy and Project Management”

  2. Hallelujah, they finally got the mud jacking done. Glad it’s done. I know it’s been hanging over you. So when do they clear you to put stuff back in those rooms of the basement?


    1. We have a number of things to do still, starting with getting the bathtub positioned correctly and its drain lines scanned for distortion or leaks. We have to choose paint and carpeting, get the painting done and then the carpeting, and then re-imagine the furniture layouts. We gave away the black couch downstairs and may replace it with separate chairs.

      So overall, I think we’re six weeks away from full use of the lower level. It want it to be done, certainly, but I want it to be done both correctly and well.

  3. Lee Hart says:

    Glad to hear it’s all over (almost). Now for the “fun” of putting everything back where it was. 🙁

    Did George Ewing ever tell you the tale of putting the new floor in Harvey’s Basement? Now *that* was an epic adventure! Just be glad your floor problems weren’t that bad!

    1. No, that one I don’t recall. Feel free to tell the tale here!

  4. Tom R. says:

    I am glad to hear that the operation was a success Jeff. I hope the recovery goes smoothly and quickly. I guess I know what you got for Christmas!

    I may be doing the same kind of project on the garage floor slab of a house we inherited from my dad. The right side has a noticeable list to starboard.
    How are these contractors listed or how do you find them. I have never searched for mudjackers before..

    1. We looked for a firm that had done both construction and restoration, and got some recommendations from various people in the house-enhancement business here. It took some hunting, granted: We’ve been working on this project for a long time. Carol is a big believer in Angie’s List, and while we didn’t discover the firm we chose there, we went to Angie’s like a sort of ad hoc Better Business Bureau, and found good comments for that particular firm. I’m sure to some extent we were lucky, but that’s almost always an issue in home repair work. So far we’ve not been disappointed.

      We also have garage slab problems, but as our garage slab has sunk as much as 7″ and broken in five or six places, we’ve decided to have it jackhammered out and repoured after the same firm stabilizes the fill on which it had been built. That’s going to wait for warmer weather. The big challenge there will be emptying the garage, which contains my metal lathe and probably 1,500 pounds of scrap metal in rolling bins.

  5. […] key boxes were blocked in behind all the other boxes of miscellany I had to pack up to prepare for the mudjacking. So no trains […]

  6. […] blew up. Settling soil has been our bane here for years now. We had to empty the lower level and get the slab mudjacked, and are still fooling with paint chips and carpet samples now that the carpet’s been torn up […]

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