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Photograph of a classic shrinkage crack in poured concrete. Shrinkage Cracks in Concrete - FAQs
Q&A on identification, cause, repair

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Concrete shrinkage crack questions & answers.

This article series explains how to identify, evaluate, & repair shrinkage cracks in concrete floors,slabs, or foundations.

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Q&A on Shrinkage Cracks in Poured Concrete Slabs

Cracked slab at front entry door (C) InspectApedia.com BrennerThese questions & answers about shrinkage cracks in concrete were posted originally at SHRINKAGE CRACKS in SLABS - so you will want to also check the diagnostic advice given there.

On 2018-04-03 by (mod) - concrete floor damage at front entry door

Nope - not for structural reasons, but you might want to seal the area against water intrusion and maybe frost damage.

Use a flexible masonry sealant.

The concrete damage in your photo is not a concrete shrinkage crack. But whenever very dissimilar materials meet, such as a concrete slab edge and the wood framing for a door threshold, it's smart to use a flexible sealant - and if the crack is very deep, yes you might need a backer rod, to minimize future damage.

I suspect the damage we see is due to frost other expansion/contraction damage at the slab edge.

On 2018-03-26 by Denny Brenner - do I need to use any kind of spacer rod

This is a picture of my front door. My home is a slab house. The foundation and slab are seperating. My question is if I chisel line it and clean it out, coat the crack with adhesive, do I need to use any kind of spacer rod in it before I pour concrete in it?

On 2017-05-29 by (mod) - can you hire us to review photos?

To avoid any possible conflict of interest and to maintain confidence of our readers, InspectApedia (and editors like me - DF) do not sell any product nor service. We provide *limited* pro-bono comment or consult when we can, expecting that we may all learn something or that photos and discussion may provide article material that might help other readers. Contributors of technical content are kept anonymous by default - unless you want to be identified.

I emphasize that for the potentially serious concerns such as the safety or structural reliability of a balcony you must have an onsite expert. Nobody can be smart-enough by remote observation to bet life and safety.

On 2017-05-29 17:54:51.362672 by Cathy

The balcony in question is located in South Florida and is exposed to the elements. What if any is the fee for review of the photos?
Thanks

On 2017-05-29 by (mod) - Is it reasonable for me to require that the Contractor remove the concrete and redo the patched job

I'm not sure you should remove and re-do the concrete, Cathy. In my opinion the considerations that would decide that question include:

1. is the balcony unsound structurally

2. is the balcony unsafe in some other way that needs attention or repair

3. are there openings that admit water that will lead to frost damage (if you are in a freezing climate) or to future rusty rebar damage to the balcony or to the building proper

4. are there openings that leak water into the building, e.g. into the space below the balcony

5. Of less significance as it does not include safety nor structural integrity, are there substantial cosmetic defects that cannot possibly be remedied by any other means

You may need a civil engineer, structural engineer, or other expert familiar with concrete construction and repair to help you decide if there are substantial issues.

You're also welcome to send us photos using the page top or bottom CONTACT link. We might be able to comment further.

On 2017-05-29 by Cathy

Balcony was "restored". Rust was removed from Rebar and Rebar was coated. Concrete was poured to restore balcony. It was uneven and with in an hour or two the Contractor came back and added additional concrete to level.

The area was not covered or kept wet for several of the required days. SEVERAL shrinkage cracks appeared and were later filled with Epoxy.

Prior to the "Restoration" there were never any cracks in the area in question One crack in particular is on either side of the support pole.

Is it reasonable for me to require that the Contractor remove the concrete and redo the patched job. I feel that this was substandard work.
Thank you for your response.

On 2017-03-13 by (mod) -

Ed

Cracks in the floor slab of a multi-story building may be cosmetic or they might be more serious. I'm way too scared to bet your life on an e-text diagnosis by a non-engineer (me).

It would be stunning if the floor slab were not steel reinforced, so the chances of a sudden collapse are probably miniscule, but a shrinkage crack that passes through the full thickness of a slab enough to leak water through directly sounds as if it certainly deserves a look by a professional engineer who has expertise in concrete structures.

Use the page top or bottom CONTACT link to send me some sharp photos if you can, and do keep us posted - as what you learn will help other readers too.

Daniel

On 2017-03-13 by Ed C

We have a lot of cracking in a 6th floor slab about 7" thick both in line with columns and spider web.
Some are all the way thru the slab. We spilled a small amount of water and it went right down to the floor below. They appear to be shrinkage cracks but their going right thru is a concern.

On 2017-02-22 by (mod) - IF repair is needed, the method depends on the crack size, shape, location.

IF repair is needed, the method depends on the crack size, shape, location. For a hairline crack it's quite a bit of work - saw-cut and fill - that might be needed if there's a concern for radon or water entry.

In the ARTICLE INDEX link given above you'll see articles on concrete crack repair methods and materials.

On 2017-02-22 by Henry Gers

Hairline cracks developed in a slab after 2 layers of concrete were poured.The adjacent slab
was poured from a single load , and has no cracks.The concrete was re-inforced with fibre.
How can the cracked slab be repaired.

On 2016-07-31 by Xman

How do you repair plastic
shrinkage cracks

On 2016-07-10 by (mod) -

If you cannot get a professional tile layer or mason to evaluate your situation you are really flying a bit blind.

For example, though there are online versions of various construction estimating tools (Such as Means' Construction Guide" you should have very low confidence in an estimate you make up by using such a resource yourself: you would only be guessing at what sorts of repairs, material, and labor to include.

Even "worst case scenario" needs some refining. What worst case? Removing and replacing the entire tile floor? That estimate won't include repairs to a damaged slab below the floor; And that estimate won't include construction or foundation repairs if the building was built on improper fill or with inadequate foundations.

You see, Anonymous, trying to make a true "worst possible case" repair cost could come up with a number in the tens of thousands of dollars. Yet the probability that that's what is really needed could be so low that such a cost estimate would be ridiculous.

In sum it makes sense to get some experienced onsite people to take a look.

Or try this: add up all of the costs of all of the repairs that you expect to make and double that number. That usually puts you in the ballpark.

On 2016-07-10 20:21:31.108269 by Anonymous

I'm considering the purchase of a fixer upper and one thing that concerns me are the cracks in the basement concrete floor. It is tiled but some tiles are cracked and a few completely off exposing the cracks. I know that everything can be repaired but I'm concerned about the cost. How can I obtain an idea in the worst case scenario if I cannot get a professional out to evaluate?

On 2016-05-22 22:57:37.043490 by Rosie

I am about to go under contract for a new site, and I already see a long crack on the floor that goes on for about 18 feet long, it is only 1/8 of an inch wide but I am still worried.


On 2016-02-29 13:59:35.274880 by (mod) -

Donna:

Baloney. Normal concrete shrinkage cracks are hairline - less than 1/16" wide. No 3/4" crack would be due only to normal concrete shrinkage. There are numerous possible causes of slab cracking such as omission of control joints, improper concrete mix, pouring under poor conditions (hot or cold), or settlement. If there is any difference in elevation between the two sides of the crack then settlement may be an underlying problem that would point to poor site work such as improper soil compaction under the slab.

I can't fortell the future, though my dad, Danelli the Great, claimed he could. But it is certainly possible that with such an abnormally large crack in your home's slab cracking will continue and will show up as damage elsewhere. I think you need an independent on site expert.

On 2016-02-27 17:16:30.795828 by Donna

Our home is 17 months old. We have cracked tiles. A crack in slab was discovered after removing the tiles (different rooms of house) We were told it was a normal shrinkage crack (it's up to 3/4 in wide at some points and 3/4 in deep). Without removing all tile how can it be determined if crack will continue or if there are more in different locations?

On 2015-12-05 17:13:01.927111 by (mod) -

If no water enters the sump pump pit then the pump won't run and you're in good shape.

On 2015-12-05 14:43:12.822721 by Mitchell patterson

I HAVE A NEW HOUSE ABOUT 4 MONTHS OLD MY SUMP HAVE NOT GONE AT ALL NO WATER IS COMING THROUGH THE DRAIN PIPE SHOULD I BE CONCERN


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