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Cinder Block Foundation Leaks

georgep | Posted in General Discussion on August 29, 2009 09:06am

Hi,

I have a question about leaks in a cinder block foundation.   When it rains hard, as it is right now,  I get basement leaks on opposite corners along one wall of the foundation.  Not a lot of water but seepage through the joints.  The cause of the leaks is that the downspouts on either end are dumping water next to the house and the grading is not allowing the water to run away from the foundation.   I will regrade along the foundation and divert the water but I’m wondering if I should do anything about the joint cracks that are allowng the water in.  Other than this the basement is very dry.  This is down Cape Cod so the soil is sandy and drainage is excellent.  I don’t think there is a lot of hydrostatic pressure here.  Plus the house is elevated above the surrounding terrain.

I plan on drylocking the basement but I guess my basic question is, are cinder block foundation joint cracks a problem and if so, can I repair them.  There is no sign of any wall movement and the wall is nice and plumb.

George

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Replies

  1. Bing187 | Aug 29, 2009 10:01pm | #1

    Are the cracks are in the mortar joints and not in the blocks themselves?

    I would hazard to guess that if the wall is not displaced at the cracks, ie, not "stepped", then it's probably not a structural issue. Depending on how big they are, you can either fix them with a hydraulic cement or other masonary patching product, or if they're large, might be better to hire it to someone that can inject it with something. I'm guessing that it must be an older foundation, as our area for the most part, has been predominately poured foundations for 30 years or better. If it's held up so far without moving, prolly ok structurally...

    I've seen poured foundations leak if drainage was a problem..One in particular where a downspout was removed by a painter and a deluge followed. Water in a previously (12 years) dry basement, which had a french drain that daylit in the back of the property.

    I would get something on the offending downspouts even if it's temporary, to avoid a constant cycle of water flowing down the outside and into cellar....could erode material under footing, wall or floor......

    If it is a more serious flaw, big crack, etc. then a more appropriate fix would be exterior excavation and damp-proofing, followed by a curtain drain and daylight/pump situation...but doesn't sound that bad from here...:)

    Good luck

    Bing

     

  2. georgep | Aug 29, 2009 10:56pm | #2

    The cracks are just along the joints, no cracked blocks and the wall shows no sign of movement.

    Thanks.

  3. FastEddie | Aug 29, 2009 10:59pm | #3

    If you paint waterproofing sealer on the inside of the block wall, all you are doing is rapping the water in the block.  You need to paitn the waterproofing on the outside to keep the water from getting into the block.

    "Put your creed in your deed."   Emerson

    "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

  4. georgep | Aug 30, 2009 12:46am | #4

    HI,

    The only time I get water is when it rains heavily and the downspouts are emptying, and only on the foundation where the spouts are.   The reason to dry loc the walls is that I'm also trying to cut down on basement humidity.  The basement humidity on the Cape is terrible.  Everyone has a dehumidifier running.  I'm hoping that drylocking the walls, and floor, will help to cut down on the humidity (yeah, I know it does nothing for ambient humidity due to oustside air).

     

    George

    1. User avater
      Matt | Aug 30, 2009 12:56am | #5

      You should be out getting piping to divert the downspout water away from the house.  Not wasting time on the internet ;-)

  5. barmil | Aug 30, 2009 01:06am | #6

    I have lived in 60+ year old houses here in Wisconsin, each with cinder block foundations, and have encountered basement seepage in each. In all cases, providing a positive grade away from the foundations and extending downspouts has stopped the seepage. Also, we removed the arbivitore so popularly planted next to the houses years ago, as they not only press into the basement with their roots, but they also gather rain water that drips straight down along the foundation wall. You can probably do simple mitigation efforts that don't require huge diggings and drainage systems. Oh, by the way, using rocks for house side landscaping will only make this problem worse, but that's another subject I could write about for weeks.

    1. CardiacPaul | Aug 30, 2009 01:39am | #7

      Barmil, what part of the state do you live?, just wondering No one should regard themselve as "God's gift to man." But rather a mere man whos gifts are from God.

      1. barmil | Aug 31, 2009 04:58am | #9

        I live in La Crosse on the west coast of Wisconsin. Rocks, I've found, tend to gather water instead of letting it move away from the foundation. Plus, they're perpetual. Once there, they're always there, moving downward into the soil. They also absorb heat, making it tough on plants among them. If you have them, get rid of them. It's backbreaking, so maybe a hire job. If you don't have them, don't consider them, I'd say. Stay vegetarian. The first time you try to plant in a rock garden, you'll curse them forever.

        1. rnsykes | Aug 31, 2009 08:58pm | #10

          They also make a nice home for all kinds of bugs that you normally don't want to invite right up to your house. Crickets especially really love river rock, and once they fine a way in, they'll be chirping away in your basement.

  6. georgep | Aug 30, 2009 02:28am | #8

    "You should be outside..."  It stopped raining. :-)

    Ok, I'll bite, what's wrong with rocks?  I'm assuming you mean the white stones that people use as mulch?  Here they use busted up quahog shells.

    George

  7. User avater
    rjw | Aug 31, 2009 10:16pm | #11

    10' + downspouts first (get the water well past the overdig area around the foundation.

    Grading second

    If the walls are already painted, don't bother with dry lock - it needs to go on clean, unpainted block, per the instructions.

    I'm not a big fan of it in any case - it's a band aid that will only last so long.


    "Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."

    Howard Thurman


    http://rjw-progressive.blogspot.com/

  8. DanH | Sep 01, 2009 03:55am | #12

    Diverting the downspouts (at least 5 feet away) and tending to grading near the house will make a major difference. Make sure there's no place for water to stand within 10-15 feet of the foundation, and no major puddles within 50 feet.

    Coating the inside of the block may help a little, but the only reliable, long-term fix (beyond grading and downspout extensions) is to excavate the outside of the foundation and apply a waterproof coating.

    As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
  9. georgep | Sep 01, 2009 06:06am | #13

    As I said the only water coming in is right where the downspouts dump and only during a heavy rain.  I'm pretty sure that extending the spouts and grading properly will completely take care of the problem.

    The only reason to drylock the walls is to help keep the humidity down from water vapor, not to help fix the liquid water leaks.  which leads to another quesstion.  Will Drylock do what I expect?    I have the dehumidifier set to 50% humidity and it runs for probably10 to 12 hours a day.  I only need to run it in the summer and I need to run it or the basement gets musty.  The upstairs is fine and we don't have humidity issues.  Running the humidifer does a number on the electric bill  (it is a new humidifier so is energy star compliant) but Drylock is expensive too and I don't want to waste the money if it won't help.  The area is Cape Cod and basement humidity is a real problem for everyone.  Most people have dehumidifiers in the basement.

    George

    1. KFC | Sep 02, 2009 12:37am | #15

      "The only reason to drylock the walls is to help keep the humidity down from water vapor, not to help fix the liquid water leaks.  which leads to another quesstion.  Will Drylock do what I expect?"

      Not really, not for long.  I've never seen an interior applied sealer that really worked for very long, whether for vapor or liquid.

      k

      1. barmil | Sep 03, 2009 03:11am | #16

        All of these postings are spot on. You can't stop outside hydraulic pressure with an interior coating of something like Dry Lok. You need to mitigate the outside water from getting in. I set my dehumidifier at 60% in the summer, and it runs pretty often, but there's no mustiness in the basement, and I don't see very much of a cost factor in its operation.

        1. User avater
          Dinosaur | Sep 03, 2009 04:07am | #17

          As the house is fairly old, it's unlikely there is any kind of vapour barrier under the slab. Even if the OP excavates and wraps the block walls with Blueskin or Resisto, he will still probably have humidity migrating through the floor into the basement.

          Dinosaur

          How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....

  10. User avater
    SamT | Sep 01, 2009 04:26pm | #14

    Grade and  divert, then see if you have any worries about sealing.

    SamT
    A Pragmatic Classical Liberal, aka Libertarian.

    I'm always right!
    Except when I'm not.

  11. AAguy | Sep 07, 2009 03:13am | #18

    My first house on Long Island had some water leaks as well although the house did have a poured foundation with cracks and not cinder blocks. I asked a friend who just so happened to be a waterproofer by profession. He said the best way to fix it was to dig all the way down to the footing a certain distance from the offending leak, clean the wall somewhat, apply mastic (tar) a layer of felt (tarpaper) another layer of mastic, and another layer of felt. I was in my mid 20s and full of spunk so I did the digging and layering and lo and behold, that fixed it! Previous to that I had tried the interior fixes to no avail. The width of the hole was about 4-5 feet at the middle and tapered to about maybe 2 feet at the bottom.

    1. barmil | Sep 09, 2009 04:00am | #19

      There's no doubt that digging down to the foundation's bottom outside and installing systems to prevent water intrusion is the best course, but few of us can afford that, or our situation may not allow that. Unless this is a This Old House project, where money seems not to be an object. Better to do the other, cheaper things suggested earlier.

      1. AAguy | Sep 09, 2009 04:20pm | #20

        The only cost to me at the time was for the mastic and the felt... cheap. The rest was my labor as I mentioned in my post that I was full of spunk!

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