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I'd like to reslope the concrete slabs on the side of my house so that water doesn't run up against my foundation during hard rains. Everything I've read about seems to indicate I should do some sort of slab jacking.

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I looked into renting a mud/grout jacking equipment but it doesn't seem to be offered in my area. However, it seems like these slabs were likely poly lifted by a previous owner, and current holes in the slabs see ideal for poly-jacking.

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Are there poly-jacking kits I can buy? I tried searching the internet but was unsuccessful. Is there a way I can hack together a machine to do poly jacking either out of an air compressor, or perhaps a pressure washer? (how about a grout jack?). What sort of pressure is needed for the injection process?

  • 2
    Those holes may be from termite treatment. – Tyson May 20 '18 at 18:32
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I suspect Tyson is right about the old holes being from termite treatment (although they should be 1' apart for that, so it would have been a crappy, ineffective treatment job). If they were from previous jacking and the slabs now need jacking, that would kind of indicate that jacking isn't a good long-term solution (and there are lots of reports that such is the case).

Aside from longevity issues, jacking isn't as easy as it looks in the online videos. Getting good results takes a lot of practice (you need to anticipate where things will end up when the material stops spreading or expanding and stop pumping ahead of time, you need a feel for how slabs will move, even just keeping thing neat takes practice). If you're talking about foam jacking, there are lots of ways that can go wrong, and the stuff is a mess to clean up.

I don't know if a license is required for using the bulk chemicals, but the reason you may not find rental equipment is the likelihood that amateurs would return the equipment in a condition that it would need to just be disposed of.

I would recommend solving the problem a different way. Leave the slabs where they are and add a layer on top. There are high strength topping materials. Make the top layer slightly wedge-shaped to achieve the slope you need.

Additional thoughts:

  • If the slabs are level and you're just getting runoff in both directions, it might be enough to just add a small cove at the house that keeps water from running off on the house side.
  • That looks like a narrow sidewalk and then not much distance to the property line. From the picture, it looks like maybe 4 - 5' from the house to the fence. Even if you get the water to run away from the house, a lot of that is still going to permeate the ground and get back to the foundation.

    There are some things you could do to improve the situation. Pull everything up, line the area with plastic and put everything back. That would create a problem for your neighbor, though. Or pull everything up, excavate your foundation and seal it, then put everything back. That would be very expensive if you could even get the equipment into the space and had a way to deal with the mountain of dirt. Another thing those old holes could be is a previous attempt to inject "waterproofing" around the foundation (not effective).

    The best solution to keeping the runoff from getting back to the foundation (after you deal with the slabs), is to bury a drain channel next to the slabs on the fence side. There are "kits" that combine pipe with surface drains. You trench next to the sidewalk and bury the system just below slab height. The captured water flows to an area far away from the house. If the ground has some slope, you can just discharge the water. If not, you can create a dry well. There are also some systems that hold the water and just release it slowly into the soil when the soil is dry. Those need to be sized for the volume of water, the extremes of rainfall, type of soil, etc.

  • The holes aren't in every slab, which is why I think it's from slab-jacking, though I have found wood damage in the house (the holes seems more like ant damage). It's actually 3 feet to the property line. Right now the slope is about 1 inch over the 2 feet toward the house, thus I'd want to raise 2 inches. The house is on a hill, so the underlying rock likely drains away from the foundation. – virtualxtc May 21 '18 at 20:07
  • Awarding this the answer as I hadn't considered the mess might explain why there might not be poly-jacking equipment. Seems like I should post a separate question about the holes / best ways to add height to a slab. – virtualxtc May 21 '18 at 20:09
  • If it's 3' to the property line, pretty much that entire area is backfill after the foundation excavation. That can't be compacted as much as the millennia of settlement of the surrounding area. It's relatively porous, and continues to settle for a very long time (likely why the slabs are still moving). You can regrade the slab surface, but 1) they may not be done settling, and 2) you're still dumping the water so close to the foundation that most of it will migrate to the foundation anyway. (cont'd) – fixer1234 May 21 '18 at 20:41
  • Think of the slab project not as a way to move water away from the foundation, but as a way to capture the water to get rid if it somewhere else (which will also slow down future settlement). If you don't put in some form of drain channel, any grading you do on the slabs won't make much difference in terms of keeping water away from the foundation. – fixer1234 May 21 '18 at 20:41
  • One other thought, consider whether you can just use the slabs as they sit. If they all slope toward the house, don't regrade them, just capture the water on the house side. The slabs are already narrow for a walkway, but you could use a concrete saw to cut away a ribbon next to the house just wide enough to lay a drain system. The drainage grates would be at slab height, so people could still walk on it and you would have use of the full walkway width. If the walkway wraps around the house, you might need to tunnel under it at some point to route the water somewhere else (not a big deal). – fixer1234 May 21 '18 at 20:57

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