Crack in new basement floor

The following email was sent to me as an attachment to an email hiring me as a phase inspector for this gentlemans new home.

Hi xxxxx and yyyyy,

I was disappointed to find a large, deep crack in my basement floor when I stopped by to see the house over the weekend. It runs more than halfway across the basement floor, and appears to be full thickness. I am concerned because not only is it unacceptable from an asthetic point of view, but also because it may represent a structural problem. Given that this floor is just a few days old, my hope is that it can be fixed quickley. Please let John know about it. I’ll try and phone you in the afternoon on mondat for an update. I can be reached at 210-867-9172. I have included a picture of the crack, considering I’m 10 ft above it looking down you get a sense of how significant it is.

This basement slab was poured 5 days ago and I would like your opinion.
I am for making contractor repair and if all else fails go to court, but I thought I’d get some non-biased opinions first. Contractor is saying that it is normal for this to happen. My Phase 1 inspection isn’t till Wed. pm.

They are very common because at the residential level virtually no one cuts the slab to make shrinkage cracks occur in planned straight lines and not where stress causes the crack to randomly occur, looking like hell and scaring the uninformed house owner…Remember: they expect the house to be perfect!!!

Most concrete floor cracks are not an issue and are acceptable. By looking at the crack posted, it is a normal shrinkage crack that I come upon frequently.

I repeat, this is not an issue.

You can’t really tell with a pic taken from 10 ft away… But after saying that, if it’s not more than 1/8 of an inch wide, and isn’t offset, I’d say the contractor is correct. However, With it being bran new, I wouldn’t let him get away with not fixing it. It can be sealed, patched and polished so you can barely see it, and no water will come up when it rains.

If it is larger or offset, then there is an issue with the pour/settlement, and something (not sure what) should be done.

Thanks everyone. My concern is aesthetic, not going to look so hot in new basement. Client is upset that it is there at all. I haven’t even seen it in person yet, but I will be getting my own pics in 3 hours.

Jack , if the guy wants it pretty, he can add a subfloor and carpet.

Though they should wait a year , for settlement issues to subside.

I’d be willing to bet the 3" stubb out was hit with the power float which,if hit hard enough could cause enough disturbance to crack the floor.

It’s also common to see those cracks around/near pipes that weren’t well bedded before the pour or weren’t deep enough.They will move during the pour and floating ,and of course, cause cracking.So,you know,was it the plumber or the flat work guy??That’s what these two thoughts wil lead to.

If the floor has steel in it ,it shouldn’t move too much.Probably the best you could do now is patch the cracks and move on.


That is correct Brian;
Concretelike other construction materials, contracts and expands with changes in moisture and temperature, and deflects depending on load and support conditions.
Crackscan occur when provisions to accommodate these movements are not made in design and construction.

All concrete has a tendency to crack and it is not possible to produce completely crack-free concrete. However, it can be controlled.

The majority of concrete cracks usually because of improper design and practices as such;

Omission of isolation and contraction joints.

Improper subgrade preparation.

The use of high slump concrete or excessive addition of water at the job site.

Low cement mix or poor ratio of cement/water; 2500psi vs. 3000psi concrete.

Improper finishing

and Inadequate or no curing.

Hope this helps and waiting for new pictures hopefull of the whole room.

Marcel :):smiley:

If water comes up through any cracks, including the cracks that occur when the slab shrinks away from the concrete walls…don’t worry about the cracks, there’s a hill of a lot more wrong!!! Repairing that crack won’t stop water from coming in the basement if there are perimeter foundation tile drainage problems and/or high water table levels.

Okay… Got Pictures.
100_0737 (Small).jpg 100_0747 (Small).jpg 100_0748 (Small).jpg 100_0750 (Small).jpg

From the looks of the cracks on-site and some of the color differences in the surface I think we had an overzealous laborer with the hose.:slight_smile:
They all looked superficial to me, but you guys give me your opinion.


100_0750 (Small).jpg

All normal cracks Jack, like others said, if control cuts are not made, this is the end product, no other way to avoid it.

Too your customer, who obviously knows nothing about concrete, I would lead him to web links explaining why concrete cracks in detail.

I don’t see an issue.

If your client doesn’t like the cracks, the contractor can go over it with a parge coat of mortar, but that will be an obvious fix showing two different colors on the floor.

This morning I poured water in the crack and watch as it just sat there. Took pictures showing no movement to prove to client they are superficial. Sent to client.

Since this is a finished section they are going to talk to contractor about a finished floor. All’s well that ends well.

Three guarantees in life. 1) You must pay taxes, 2) concrete cracks when curing, and 3) We all die at some point.

Thanks Peter - Your an optimist right?

Ask the builder to get a copy of the amount of water added (if any) to the concrete at time of pour. The drivers are suppose to noted any amount when they turn in their tickets. If everything looks good then its a cosmetic issue / nature of concrete.

It sounds like your clients do not have realistic expectations…I would discuss this with them. If you see that it is still the case, then refund their money (with a release) and bid them adieu.


Oh, they’re not mad at me. I just turned them over to the contractor after telling them that it was a relatively normal condition.
After the inspection we walked across the street to the one that was just poured and lo and behold “cracks”.

for me alls well that ends well.

And that will crack later too. Same as the floor in the same place, unless they wait at least a year to repair it. Concrete cures for 50 years and will shrink the entire time. Most of the curing process occurs during the initial 27 days from which it was placed (90%). the rest occurs very slowly dependent on a variety of factors. One year is usually accepted as the right time to do repairs due to cracks of this nature. But it is a cosmetic problem, the contract between the builder and purchaser should be reviewed to determine the obligations between them. Really seems as though a little education for the buyer could go a long way here unless the builder didn’t use the correct mix, slump, or reinforcement specifed by the engineer of record.

So be it.