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  1. #1
    Join Date
    Sep 2014

    Default Water Main Penetration Leak in Cinder Block Basement

    Hello all.

    I have a cinder block basement with a plastic/rubber water main entering the house through a hole in the foundation.

    Last winter we had a very heavy snow and a quick thaw. During that time, a water leak developed around the pipe.

    I cleaned around the pipe as best I could and filled it in with "Great Stuff". Over top of that I sprayed quite a few layers of Leak Sealer (forms a a kind of rubbery seal) then silicone on top of that.

    It looks sealed well enough, and that is the only time I've had a leak before or since. However, going into winter, I am concerned that the water will still leak into the outside of the foundation wall and could force its way other places in the cinder blocks, doing damage I may not see as quickly.

    Our plumber recommended excavating to find the pipe outside and patching the exterior wall with hydraulic cement and tar, so I began digging down to find the pipe (around 3 ft below grade).

    However doing some research ****** I have seen lots of conflicting opinions about hydraulic cement and exterior patching. The preferred treatment seems to be a polyurethane injection from inside, but I also read that is not suitable for cinder block foundations.

    I am no expert and would appreciate the forum's help and guidance. What is the best way to ensure no water gets in?

    Thanks in advance!

  2. #2
    Join Date
    Jul 2010

    Default Re: Water Main Penetration Leak in Cinder Block Basement

    Look into a product called THOROSEAL, I've had good luck with it, even though I don't get any snow here.

    Call their customer service for guidance.

  3. #3
    Join Date
    Jan 2008

    Default Re: Water Main Penetration Leak in Cinder Block Basement

    I'd do what your plumber recommends as water is best stopped outside of the structure. I would add one small (say 1/4") hole at the bottom of the foundation wall inside to allow any water that did get in to have a safe place to drain out instead of pooling inside the block. If your foundation is already waterproofed on the outside there may be a more compatible sealant instead of "tar" (which I take him to mean black-jack or NP1 type sealants). Sadly there are some who will poke a hole in anything which is in their way without regard to anything except getting their pipe (or wire) through; very unprofessional but it happens.


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