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I know cement cracks...but...

Posted by mebke33 (My Page) on
Tue, Sep 11, 12 at 20:46

Our foundation was poured about a month ago. Today I noticed a vertical crack in the wall. The crack runs from the floor all the way to the top of the wall and is visible on the top of the wall also. Should this be something to be concerned about? The first pic is the top of the wall. The 2nd & 3rd show the crack on the inside of the wall. It runs along the point where two of the pans met. I know cement always cracks but this looks concerning to me. Thanks.
Crack1
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Follow-Up Postings:

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RE: I know cement cracks...but...

I'm curious, Is this a basement wall? Did they already backfill behind it? And if so, how long did they wait before they backfilled? The reason why I ask is because they could have improperly backfilled on green concrete (didn't wait long enough) or their method of backfilling was incorrect. I think some more details might help someone with real expertise to chime in.


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RE: I know cement cracks...but...

This is a 9ft basement wall. It was backfilled about 10 days after being poured. The crack didn't show up after they backfilled. I just noticed a day ago.


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RE: I know cement cracks...but...

If the imbalanced fill is greater than 4 ft the floor structure is normally installed before the backfill in order to avoid this kind of cracking.

2009 IRC code section R404.1.7
"Backfill shall not be placed against the wall until the wall has sufficient strength and has been anchored to the floor above, or has been sufficiently braced to prevent damage by the backfill".

It is also possible that the wall has no reinforcing steel which would be unusual for a basement wall of this height. Was the wall engineered? Is there any independent quality control? The building inspector should see the wall before the floor is installed but there is little that can be done at this point.

Hopefully the exterior "waterproofing" membrane was something that can bridge cracks like cold sprayed modified asphalt instead of asphalt based "dampproofing" and there is a continuous footing drain.


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RE: I know cement cracks...but...

Get your contractor to explain what has happened, what has been done to ensure no water/moisture leakage and no structural instability. Then ask your local building inspector to visit and view the situation. Then decide if remedial action is required. Good luck!


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RE: I know cement cracks...but...

Where is the waterproofing? What are the soil conditions and drainage like? If the wall isn't greatly out of alignment and hasn't collapsed, the real issue is how was he wall waterproofed because I don't see any in the photos. (However, I would sight the wall to be sure it was not out of alignment.)

Because a building inspector cannot be on site often enough (or early enough) to catch a builder backfilling without the required bracing, it is usually ignored and realistically there is nothing he can do when shown a crack that a builder can claim was due to some other issue.

Building inspectors have an obligation to the city, county or state not to you. As the property owner you have an obligation to build the house to code so if the inspector rejected the wall you would have to pay to replace it and then chase the foundation contractor for that cost.


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RE: I know cement cracks...but...

As suggested above, it looks like the excavation was backfilled without bracing or floor structure on the foundation. At least, neither are visible in the photo.

Under the government mandated Warranty Programme I build under, foundation cracks exceeding 2mm must be repaired. If there is vertical or lateral movement at the crack, further investigation is required.


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RE: I know cement cracks...but...

How would that be repaired worthy?


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RE: I know cement cracks...but...

This wall is in a storage room & has the interior of the garage on the other side. We have been assured by the foundation guy that this crack is due to contraction from 100 degree temps when the walls were poured. There is no displacement of the wall at the crack and it still appears straight. The house has interior and exterior drain tile. The outside of the wall has waterproofing that is supposed to bridge cracks up to 1/8 inch. We will still have the inspector take a look. Thanks for all of the replies.


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RE: I know cement cracks...but...

What other shortcuts is hits bozo going to take?

Watch VERY carefully.

They have already called their basic competence into question.


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RE: I know cement cracks...but...

How would that be repaired worthy?

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Epoxy injection foundation repair Photo: Heather Joy Investments Ltd.

assured by the foundation guy that this crack is due to contraction from 100 degree temps when the walls were poured.

Very possible. However, such cracking could have been avoided by the appropriate mix from the ready mix supplier and/or on-site precautions by the forming contractor, builder and/or general contractor. But, of course, all these things would have taken time, forethought and knowledge.


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RE: I know cement cracks...but...

That's just nasty to call that contractor a bozo and incompetent. It's most likely a shrinkage crack and if properly treated of no consequence. Pouring concrete at a 100F temperature is very unforgiving, even with a properly adjusted mix. Just shows that brickeyee has absolutely no experience.

About worthy's repair suggestion: Good Luck getting epoxy into such a narrow crack. You'll have to make that gap much wider with a concrete saw. Total overkill for such a small defect.


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RE: I know cement cracks...but...

"That's just nasty to call that contractor a bozo and incompetent. It's most likely a shrinkage crack"

Could have easily been prevented.


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RE: I know cement cracks...but...

According to the American Concrete Institute publication, Structural Crack Repair by Epoxy Injection, Field Guide to Concrete Repair, "Depending on the specific requirements of the job, crack repair by epoxy injection can restore structural integrity and
reduce moisture penetration through concrete cracks 0.002 in.(0.05 mm) in width and greater."

Before any repair is undertaken, the cause of the cracking should be impartially investigated, including whether it penetrates through the wall and time taken to see whether the crack is stable. A gauge can be set in place that will measure subsequent movement.

See photo below of typical drying shrinkage cracking Photo: Guide to Concrete Repair United States Department of the Interior, Bureau of Reclamation, Technical Service Center


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RE: I know cement cracks...but...

Sure does not look like the typical shrinkage cracking.

There are real structural reasons not to load unbraced concrete walls quickly.

It causes cracking.

Who would have thought?


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RE: I know cement cracks...but...

Poured walls have so much lateral strength that builders get used to getting away with backfilling without a floor structure or bracing. But sometimes the gamble goes against them.

OP Our foundation was poured about a month ago. Today I noticed a vertical crack in the wall.

So the foundation has been sitting for a month with nothing going on. Great scheduling.


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RE: I know cement cracks...but...

Looks _exactly_ like shrinkage cracking that I saw this summer on a job that was poured at 108F. The cracks developed within a few hours on a slab that was not loaded structurally whatsoever.

In addition, this crack that we are talking about is along the line where two forms meet. It likely dried out too fast (vs. properly cured) along this particular area which lead to a shrinkage crack, which is due to loss of volume due to loss of water.

Worthy's picture looks like surface crazing, which is a shallow cosmetic problem, not a structural problem. I'm not sure if he is serious that surface crazing should be repaired with epoxy ?!?


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RE: I know cement cracks...but...

Over 30 years ago when I knew way less about building than I do now, I moved into a new condo that had a couple of cracks wider than the one shown above. The walls had been quickly poured just before an unusually cold winter, and were left without doing further work until spring. Not sure if cracks were created by freezing and expanding of water between wall and clay soil. In any case, an epoxy similar to that shown by worthy was put on the cracks on the inside of the wall, and they never leaked during the almost 30 years that I lived there. About 5 years ago, we had to take down a paneled wall that covered one of the cracks. Looked as pristine as the day it had been repaired, so a repair done correctly should solve the problem.

Anne


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RE: I know cement cracks...but...

Warm and wet.

In very hot weather taros serve the purpose of keeping the sun off the curing concrete, but wetting it down is required.

If it dries out instead of curing by hydration it will never develop full strength.


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RE: I know cement cracks...but...

Worthy's picture looks like surface crazing, which is a shallow cosmetic problem, not a structural problem

The pic and description are from p. 38 of the Guide to Concrete Repair United States Department of the Interior, Bureau of Reclamation, Technical Service Center It is of a horizontal surface.

A shrinkage crack is not necessarily a structural problem. Even if it leaks, it can be repaired, as with epoxy in the picture I posted.

But in this case, an onsite examination by an impartial expert is needed to be sure exactly what kind of crack it is and if it is enlarging.

Here is a link that might be useful: Causes of Concrete Cracks


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RE: I know cement cracks...but...

Hot weather seems like a questionable excuse for a full height crack in such a tall foundation wall. This is a wall not a slab so I strongly suspect the contractor stripped the forms way too soon even if the walls were braced during backfill and the required rebar was installed (the wall is too tall to be unreinforced).

Beware of any contractor who blames the weather.

Watch for additional cracks; the biggest issue is the possibility of settlement.


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