Greetings All,
I have noticed a hairline crack in my poured foundation wall. The foundation is 3 years old, poured concrete basement. I specified 10 inch thick walls by 9 ft. high walls and the floor deck was installed before the excavation was back filled. The floor is poured too. I noticed the crack today as I was taking measurements for drawings to finish off the basement. I never noticed it before, but I’m sure I would have noticed if water was seeping in. The crack is very narrow..can’t fit the corner of a dollar bill in it. It seems to extend from the mud sill down the interior surface of the wall about 7 feet. There is no apparant buldging in the wall. Foundation drains are working well so I wouldn’t expect hydraulic pressure to be a culprit.
Should I be worried? Is the crack a symptom of a bigger problem or is it par for the course with a poured wall? I’m especially concerned if I were to continue with my plans to finish off the basement.
I’m not a builder but I am a hard core do-it-yourselfer. I admit I don’t have sufficient experience in this arena to know what might be the problem or if there even is a problem.
By the way…I did not build the foundation. A pretty big, reputable poured wall contractor did the work as a sub to my G.C.
I look forward to hearing from the readers of the forum.
Thanks for your advice.
BillB
Replies
I got a quick crack education when I asked my engineer to investigate some cracking in poured foundations. Vertical cracks, not spreading, not through = minor, very common.
Horizontal cracking = call him asap.
I would think that so long as the proper amount/placement/size of rebar reinforcement was used, you'll be absolutely fine...other than possibly allowing moisture to enter.
I was taught a long time ago that there are two types of concrete; the kind that's cracked and the kind that's going to.
Sounds like a shrinkage crack. You might have improved things a bit by using a low-water mix and fiber additive. I would not be concerned about it.
There is a saying: "All concrete cracks eventually." Like all such sayings it's not 100% true, but there's a good dose of truth in it.
If the crack is essentially vertical, and there's no displacement out of the plane of the wall (such that a ruler won't lay flat across the crack) then it's "normal", so long as it's less than 1/8" or so.
The crack should not present a leakage problem so long as the wall is waterproofed and tiled on the outside in a "modern" fashion. Unfortunately, this is where contractors often skip steps, so it's hard to give an iron-clad guarantee.
I'm sure it is a shrinkage crack....commonly caused by watered down concrete when it was poured.
Add another vote for "probably nothing to worry about."
If you want to keep track of it, you could epoxy a small piece of glass (like an old divided light window pane) across the crack, put a few strips of duct tape over it so nobody gets hurt if it does break, and wait.
Home-made strain gauge.
The tensile strength of glass is very high but the work of fracture is very low.