New Build - Are These Concrete Floor Cracks Concerning?

We are building a home (6500sq.ft, 2 story + basement). We’re about done with 4 way - but we noticed the other day what seemed to be excessive cracking in the floor.

Builder has looked at it (so he says), and does not think it’s a big deal. Here are some pictures, and a video.

Should we be concerned? Keep in mind, most/all of these pictures are in different parts of the basement, and this is not all of them.

Picture 1
Picture 2
Picture 3
Picture 4
Picture 5

Here’s a quick video, around 50-55 seconds in, I stomp on it and a bunch of dust comes up from it, but you can see how it’s all connected when I stomp on it:


Adam Where are you located?
How long ago was the floor poured?
How cold was it during the pour?
Were you there for the pour?
Did you happen to see what was laid under it (type of base)?
Any other info will be important for someone to help understand and help.
While shrinkage cracks are normal these do not appear to be normal. The concrete gives the appearance of being poured to wet in your photos and parts of the video. Also there was a lack of control joints.

Looks bad to me. Not normal.

Wow nothing normal about that. Hope you’re not in a high radon area. Concrete does crack but nothing like that. There are some really knowledgeable people here, I’m sure they will chime in.

No not normal at all. Have a structural engineer evaluate. One with court experience. You got a courtroom in your future.

Typical concrete cracks are 1/8" wide or smaller. These cracks are of concern. There’s no expansion or control joints which is unfortunately common for residential pours. The cause of the cracking could be one or more of a few things such as poor soil prep, poor concrete mixing, poor installation/finishing,etc.
You’re doing the right thing with pictures and video. If it were my basement floor cracking like this my next move would be to hire an independent structural engineer to evaluate. Was there a soil test done?

IMHO you need to bring in an engineer to assess.

Take additional pictures with a dime coin or tape measure across the cracks to provide scale. You are likely going to need those photos later .

Holy carp!

No, this is not normal in any way, shape, or form! Your video shows (as if) the slab was poured on sheets of plywood and is only a couple of inches thick! There is NO way that someone jumping should be able to move a concrete slab like that, even if cracked!

As I agree it will take an engineer to figure it out, I would also get the local AHJ involved asap, and be prepared for him to place a hold on the project until the problem is taken care of, which could include tearing up and re-pouring the slab.

Remember though, all of our comments/opinions are based on a few photos and a video, and should not be taken as fact… we aren’t there. It will take an Engineer being on-site to get to the facts of this matter.

Good luck. Please keep us informed as to the outcome.

My question would be, why is there sand coming out of the crack (or is that sawdust)? No vapor barrier? What type of reinforcement was used? Slump? Those cracks are a big problem…

That is a serious cracking problem. There is no way a 200 pound man could move large slabs of 4" concrete that was properly placed by jumping on it. I would notify the bank to withhold all payments to the contractor until this issue is resolved. You will need a structural engineer to check or perform the following:

  • Core/drill holes to determine slab thickness
  • Determine fill material under slab
  • Amount of reinforcing steel, if any
  • Void spaces present under the slab
  • Floor elevation survey with a contour map overlaid with the crack pattern

I would not be surprised if that slab has to be totally removed and replaced.

Find yourself a good attorney, I am pretty sure your going to need one. GOOD LUCK

Is this a custom home by itself or in a sub-division. If the builder has other homes in the area you may be able to get some pictures of the prep work on another home for reference down the road.

Wow! Just, WOW!

Follow Randy’s advice. Tell your builder to halt all work until the issue is resolved and corrected. You may also want to talk to the head of your local building department and get them out there. I can’t image how this would have passed their inspection.

My condolences to you, as I think you have quite an an ordeal ahead of you. Good luck with it.

Unfortunately I concur, from what you’ve presented this could be very difficult and time consuming to remedy, even without lawyers involved.
If it’s as bad as it looks I hope that builder is fully insured.

Also where is the plastic vapour barrier under the sill plates of all the framed walls?

Good comments. Especially by both Mr. Mayo, P.E. and Mr. Evans… Good luck!

So I went to the house this morning to take more pictures but with a dime / tape measurer to get a sense of scale.

I saw there were some other questions above, I’ll make another post with answers. Thanks for all the responses and help!

Pictures (most are cracks at different locations, and there are a couple close-up pictures at the bottom):










On this one there was a loose concrete rock that wasn’t even connected, so I took it out temporarily so I could see inside:


We signed on the house when the foundation and concrete floors had already been poured (no framing or wood yet). So I we didn’t get to see it actually get poured or what was underneath. I do know that the soil in that area is very very fine - almost like Ash in some places.

I’m assuming the temperature was pretty warm, as it was poured around August-ish.

Located in Utah (Salt Lake County)

We did, fortunately, hire a lawyer a long time ago when we noticed a few other issues. However, he has a builder’s deposit of $80k - so it’s not as if we can just walk away. This concrete issue (especially if they need to tear it up) is going to be the last straw and we may just walk anyway.

I heard back from the builder yesterday in a text - he said he went and checked it out. Here’s his response:
“I was out there today and looked at it and I think it will be just fine but I want to verify a couple of things so I will have my engineer come on site and do an assessment. I will get back to you soon as I know but otherwise I think it is just fine. The dust that comes up from below is a result of the powder when that dirt out there gets really dry. That is very common.”

I don’t know if that is true or not - don’t know enough about building / construction to make an educated guess.

We are calling some inspectors today to see if we can get any out there to take a gander.

Thanks for all the responses - definitely very eye opening. I posted these on another Home Construction forum and they all had similar things to say.

Adam, you can’t trust the builders word or his “engineer”. Ask if the engineer is licensed.
I would hire your own engineer as this will require at least one. Structural and soil.