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Preface

The proper way to seal any kind of water leakage in a concrete wall is from the outside. That is not always practical, as in this case. This question is about alternatives to solve the problem, and alternatives do exist. Solutions such as interior surface coatings, and apparently hydraulic cement, are not effective. However, some other solutions are available, and I'll mention a couple that I know about below.

Background

About a year ago, I posted the question How to seal a pipe pass-through in a basement wall. The gist of that question was two pipes passing through a poured concrete foundation wall (one an iron sleeve, one a PVC sleeve). Foam had been used to seal the gaps between the sleeves and the wall. After 15 years, ground water had started to leak in around the sleeves.

My fix included hydraulic cement (recommended on how-to sites as the proper solution). However, the hydraulic cement appears to be water permeable. So I'm back for phase 2.

Previous Solution

The typical contractor solution at construction is to fill around the pipes with spray foam. The foam is not rated as water submersible or even waterproof (probably why the old foam failed), so replacing it wasn't a solution. I ended up cleaning out all the old foam, cleaning and sealing the surface of the iron sleeve with neoprene-based adhesive, and then packing the voids with hydraulic cement. The cement has adhered well, but after 10 months, water is seeping through it. Apparently, the stuff is porous.

Current Condition

A picture of the current condition (click on it for a larger image):

enter image description here

Below the iron sleeve on the right (the original issue), the hydraulic cement is darker from the moisture and you can see some efflorescence. The bigger problem is the PVC pipe on the left, which I didn't think would be a problem to seal. The hydraulic cement around that pipe is visibly wet, and enough water gets through to drip.

Constraints

  • This can't be sealed from outside. The exterior of that wall is not accessible without significant destruction and reconstruction, which would be cost-prohibitive.
  • The walls are 8" thick poured concrete, so common solutions for tapping cinderblock walls aren't applicable.
  • Relieving the water pressure from the inside may not be practical (busting up the basement floor, tunneling under the footer, and creating a drain channel to an existing sump pump). The house is located next to a community water catchment field, so the water table is high. A sump pump would need to drain ground water from several acres to stay ahead of the water table, and the discharge goes back into that same field.

So this is a candidate for an alternate solution designed for when an exterior fix isn't practical.

Potential Solutions

I am aware of several possible solutions:

  • Injecting sealant into the wall: This is commonly used for structural cracks and leakage problems. Epoxy is injected into cracks for structural repairs, Polyurethane is injected into cracks and pipe pass-throughs to seal water leaks. These are injected the full depth of the wall and are supposedly stronger than the concrete, itself.

    In my case, I would need to break up the hydraulic cement and then seal the gaps with an injected polyurethane system (professionally done high-pressure injection or a DIY kit like this; short video of the DIY process here). There are a few brands of such DIY kits. The kits aren't cheap ($100 for each pass-through), and professional injection is several times that cost.

  • Control and direct the water flow rather than trying to seal it out: This is commonly done with cinderblock walls. The cores are tapped so water has an easy path to a collection system and goes to a sump pump for discharge. Sometimes the interior walls are then lined with a waterproof membrane to control humidity.

    In my case, the basic idea would be to drill a channel in the hydraulic cement directly below each pipe so water has an easy path to drain and is not under pressure. Connect these to tubing that runs down to a nearby floor drain.

Question

Has anyone had experience with these (or other) solutions and can share how successful it was long term?

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  • What makes this task difficult, if not impossible, is the requirement, "This can't be sealed from outside." Successful methods of sealing require application from the side with pressure, i.e., ground water infiltrating from outside. You might think of a way to do this from outside. Jun 11 at 2:17
  • @DrMoishePippik, That is the right way to do it, but there isn't a way to access the exterior of that wall without massive destruction and reconstruction. The cost would be prohibitive.
    – fixer1234
    Jun 11 at 2:30
  • There are epoxy compounds that can be injected under pressure to seal cracks and leaks in poured concrete walls from the inside. I had that done (or the builder did) to a newly constructed home. This was done by a 3rd party, not the builder, but at the builder's expense. That held up fine, no leaks in the 20 years we lived in the home.
    – SteveSh
    Jun 11 at 11:39
  • @SteveSh, now that you mention it, I recall that technique. It's worth investigating. Thanks.
    – fixer1234
    Jun 11 at 15:58
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The problem is that it can only be sealed form the other side.

On this side the water pressure will tend to blister or spall any sealing compound you apply, applied on the other side the pressure will tend to push it against the wall.

If the conduits are sealed into the wall and you can keep the other side dry (perhaps using a de-watering pump) it may be possible to clean them out and get a seal in there and then back the seal with cement or sand-filled epoxy once it has cured.

on the other hand it may be possible to dill a hole through the wall and inject a large quantity of some sealing compound and have that block the leak

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  • 100% agree with sealing this from outside. Why do you say you can't do that? A good sealing compound to use on the outside is Bentonite clay which is available in many locations. Check your local Vermeer or Ditch Witch dealer. Just dig a hole past the bottom of the pipe and dump enough Bentonite, dry, into the hole. Then backfill.
    – jwh20
    Jun 11 at 12:47
  • @jwh20, I also agree with sealing this from the outside, but digging a hole implies digging through soil, which isn't the case. See comment on the question.
    – fixer1234
    Jun 11 at 15:54
  • @fixer1234 All I see is the statement "exterior of that wall without massive destruction and reconstruction". I'm not clear why you cannot explain what is in the way.
    – jwh20
    Jun 11 at 16:02
  • @jwh20, it's always good to question the assumptions when those can stand in the way of a proper fix. In this case, the cost and practicality of accessing the exterior of that wall is something I'm familiar with. Getting into a discussion of that is really a different question, and I don't want to sidetrack this thread when there are potential nondestructive solutions that can be accomplished from the inside, like injecting a sealant into the wall, or letting the water in and routing it to a floor drain.
    – fixer1234
    Jun 11 at 16:26

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