All, I’ve got a concrete basement that’s 20 years old. In that time I have some water intrusion problems but was able to remedy them by unplugging gutters and raising the grade of soil around the house. What concerns me are the numerous cracks that have added up over the years. No, I’m not getting any water through them, nor do I have any cracks in the walls or jamming doors. Two of the cracks, 1/32 to 1/8, are about 8′ long and horizontal. Two other cracks are on two corners in the shape of a V….about 1/32. I’ve injected two other vertical cracks with epoxy. Should I follow up and inject the others or just write them off as cosmetic aging lines. Keedman
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I'll ask a question, just to get you back to the top of the queue.
These are poured concrete walls, right ? Eight foot long horizontal cracks in poured concrete walls ?
Yes, poured walls.
A 20-year-old basement without cracks at least 1/8" wide would be unusual. (Yeah, some folks will chime in to say that there should be nothing over 1/32 or so, but they're talking better than average construction quality.)
The cracks to worry about are ones where the two sides of the crack have not simply moved apart but have "slipped" relative to each other, and even there you need more than 1/8" movement to make it worrisome.
I agree its almost nothing to sweat. Up to an eighth . . . it goes back to the two guarantees you get with concrete. It will crack, it wont burn.
How to tell if you need to sweat it - first, if there is water coming through, which you said there isnt, and second, if the movement continues, especially continues in any kind of dramatic fashion over time. I know thats really subjective and you can't define it but one thing you can do is take a small piece of glass like a microscope would use, and place it over the crack, with two dabs of epoxy holding the edges on either side. Score, but dont break, the glass along the crack, and label it with a date.
Now if it keeps moving, first the glass snaps at the line. Then, you can measure how much, left right up down whatever, and at least have some kind of basis for whether or not to worry.
I've seen a ton of basements with cracks all over that were nothing to worry and others with only one tiny hairline that water poured through. Its a judgement call most of the time.
Real trucks dont have sparkplugs
An easier method is to put a strip of the clear mylar packing tape across the crack, and then cut it on the crack. Put on one of the post-it bookmarks, so it is stuck to the tape on one side and extends over the other. With a fine line sharpy marker draw an "x" on the end of post-it so that half is on the post-it and half on the tape.
If you have movement, the intersection of the "x" moves and you know how much.