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Cracking at concrete block walls

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  • Cracking at concrete block walls

    How much cracking should be expected for a 50 year old house that is of concrete block construction. There are quite a few cracks around windows and doors. Some have been patched over and are recracking. Is this normal for this type of construction material or should I be concerned about movement/settlement? There are no expansion joints present.

  • #2
    Re: Cracking at concrete block walls

    I guess the question that I would ask is: is the cracking a problem? If so, how is it a problem and how much of a problem is it? I am not sure that there is a “normal” amount of cracking for a 50 year old block foundation. None is ideal, but unlikely. And if there is a "normal", then it would only be a numerical average and would not help you in your specific case. When you say your foundation has “quite a few cracks” this doesn’t tell me much. Are they long? Wide? All the way through? Do they leak water? Leak air? Create structural sagging & sticking doors, etc?

    What is important to me why the cracks are forming and the problems that these cracks are causing. It would be nice to know if the wall is still moving. One trick I use is to take a small piece of glass like a microscope slip cover and epoxy the piece of glass so that it bridges the crack(s) and if the foundation is moving, it will crack the glass. It the glass does crack, then you know your foundation is not stable and perhaps you need to determine what forces are acting on the foundation. Is there water leakage that has developed that could undermine the support? Someties a blocked perimeter drain or downspout can lead to soil erosion and undermining.

    Another thing to check is to determine if the foundation dips or bows in any direction. String some lines along the top and bottom from end-to-end and see if the wall is out of allignment. Then use a straight edge to determine if the wall is toed in or out from top-to-bottom. If the foundation is straight and fairly stable, then epoxy the cracks and see what time brings. Small cracks are normal and to be expected. Large leaking cracks are not acceptable. Some force is required to create the cracks. Your detective work should be designed to expose the forces at play; settlement; water leakage; side-thrust of soil; etc.


    • #3
      Re: Cracking at concrete block walls

      Since I have a 50 year old block house with cracks, let me ask this: how wide are the cracks? How much is the sag horizontally, how plumb it is? Do you have water ingress? I did. Read on.
      When I had the foundation dug out we found the footing had broken. The footing drains were renewed and the webs were filled with concrete and a few rebars about every six feet. The house isn't worth the cost of two new foundation walls. In the two years since the project was done, there has been no visible movement. The basement is dry.
      The house still has a sag as the foundation only stabilized and the house wasn't lifted and leveled.
      You must judge how much investment is warranted.



      • #4
        Re: Cracking at concrete block wall fence

        Good day. I was browsing the web and I have a problem with a neighbor's block wall that abuts my property. The block wall is about 32 years old, and it has a concrete retaining wall below it (there is a vertical crack in the retaining wall near where the tree was). The wall is approximately 50 yards long, and abuts at least six properties. The blocks are rectangualar, about 6" tall and maybe 14" wide. No blocks are missing, The wall may tilt a few degrees at the top (it's about 6' tall on my side and about 9' tall on the neighbor's side. The neighbor thinks the wall has been damaged by a tree that used to be on our property. He is most concerned about spaces between some of the lower bricks where there is no grout. He thinks the wall has been comprimised and is in danger of collapse. Initally, I thought perhaps he was correct, however I drove around the housing tract, it seems that most of the exact same type of block walls are missing grout in the same area, and clearly there is erosion and stain evidence of water has passing through these groutless areas of wall as well. The missing grout is at ground level on my property, and about three feet high on his property which is physically below mine. It seems to me that by comparing the properties in the tract with simillar walls, that this missing grout is intentional and actually some type of drainage system. Are you aware of such a design? There is no other drainage system in the back yard that I'm aware of, so perhaps this design would make a lot of sense?

        Thank you!!