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I have a wall in my basement that is a giant piece of rock, the rest of the foundation was built around it. The rock has suddenly sprung 100 leaks, which I have tried to seal with hydraulic cement but had no success.

Basement does not have a sump pump and I've called every contractor within 75 miles and nobody can come for a month.

I'm trying to stop the water so that a sump pump by using a piece pressure treated wood and caulk, but because the floor is wet, I can't get the caulk to set.

Help! Is there any way I can make a water tight seal between wood and concrete while water is flowing?enter image description here

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  • Try polyurethane caulk, like Vulkem.
    – RMDman
    Commented Sep 5 at 2:59
  • Sanity check: when you say the rock has sprung leaks, do you mean water is coming through the rock itself, or from the junction between the rock and the concrete? Possible solutions are quite different for the two cases. Also, see other answers regarding basement leaks; after you deal with the immediate crisis, the most effective response is often to keep water from building up along the foundation to begin with.
    – keshlam
    Commented Sep 5 at 13:13

2 Answers 2

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In short, there is no way to seal that concrete atop rock. Concrete is porous, and has low tensile strength (though high compressive strength), so that water can burst though it.

Plug one spot, and it will leak elsewhere. Paste over the whole foundation, and water pressure might even spall off some of the surface. If the leak were along a foundation wall, it would be a feasible DIY project to dig out the wall and place a vapor barrier outside the foundation. However, it is not a simple DIY project to break up the floor and install the vapor barrier underneath.

So what can you do?

  • Best is to prevent water infiltrating from outside.

    • Landscape so that water runs away from the foundation.
    • Direct rain gutter downspouts away from the house, and install an extension, such as one of these.
    • Avoid watering plants near the foundation.
    • Install French drains around the perimeter.
    • If the water table is high, provide a way for it to flow to lower ground.
  • However, for the immediate issue, you might try using a portable pump that can be used on the surface of the floor, such as this.

    Without a sump cut into the concrete floor, though, a pump cannot pull up all the water. The one cited claims it can draw water within 1/8" (~3 mm) of a surface, which still leaves standing water. Further, the water depth would not be sufficient to activate a float switch, so you would need to monitor the pump, turning it off when the water level drops.

Even with a sump, water would still flow over the floor until it reaches that lowest spot, leaving the basement damp, so best is to stop it outside the house.

Items cited are for illustration, not recommendation.

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  • Re: Automating pump operation. A Tsurumi Pump Surface Level Switch ought to work with various pumps. I've used one with a LSC1.4S Pump. Set the pump at the lowest spot on the floor and the switch next to it. That should prevent running the pump dry. (Oh my. The prices have gone up considerably since 2022. Yikes,)
    – HABO
    Commented Sep 5 at 19:22
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I recommend 885 Tropi-Cool Wet Patch White 100% Silicone Leak Repair Sealant

It works on wet surfaces and even under water.

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