Slab foundation..House built 2008 Southern Calif.

The floor covering has not been laid down. I did the inspection. This is virtually brand new house that was auctioned off. None of the cracks were over 1/8 in. The pic that I drew on went across the family room. Is this normal shrinkage ? Or should a recommendation be made?

Being that there is no bearing load around that area and if there is not displacement I would consider it normal and move on… concrete will crack…its just a matter of where and to what extent.


That’s a fairly good-sized crack for a 2008 home in Southern California.

Is your first picture indicating that there are two cracks parallel to each other? If so, judging by the proximity of the cracks to each other, and the size of the cracks, I would call it out. I can only think of one (maybe two) reasons why shrinkage cracking would occur as mentioned.

Expansive soil can expand pretty quickly under the right condition.

We’ve also had a few small quakes out here recently that might have exacerbated the problem.

That’s not all…my son texted me some live photos yesterday of the Santa Barbara fire as he was driving thru. There was a 4.2 quake in Ojai also and he said he had heard rumors…something about a plague of locusts next week?

No doubt. I’m packing up and getting the heck out!

If the crack does not extend to the foundation wall, the concrete is not displaced, the crack is discontinued in nature, then its going to be shrinkage.

An earth quake is not going to present that type of crack, in the middle of the room while not extending to the side.
If you have cracking as a result of earthquake…there will be cracks in the foundation as well…not just in the middle of a slab floor where upon the crack doesn’t even extend to the foundation wall.

Looks like they already have the baseboard up…a tell tale sign would be to see if there is spacing between the foundation wall and the slab itself which is directly related to shrinkage and is normal.

If anything, it would be seal for radon purposes…then again, that crack may not present such an issue is 6 mil poly was laid.

Picture 1 doesnt show any clarity…
Picture 2 shows the crack to be fairly straight…which their could be a keyway under same.
Picture 3 is showing approximately up to a 3/32 of a crack without any displacement whatsoever, vertical or horizontal…I use that to rule out any earthquake effects.

Just to be curious…what are you going to say when “calling” this crack (evidently 1 crack) out…“noted one (1) small crack less than 1/4 inch in width with no displacement, in the middle of the room extending approximately 4 - 6 feet however same does not extend to the foundation wall; further evaluation is warranted by a soil and or structural engineer.”

Not to be facetious but if you think its a structural issue (which it seems that some of you do) then calling out anyone besides a soil and or structural engineer will be useless.

Ken made a good point in mentioning expansive soils…here in NC we went through a drought for several years (some say we still are in one in our area)…we then had a short season of extensive rain several years ago…what do you think happened to all the basements and slab homes in the area…talk about insurance claims being filed (and often rejected).

If anything I may make mention of it in the body of my report, simply stating that no displacement was noted, the crack was limited and should be filled…unless you have pictures of crackings in other areas of the house including the foundation, wallboards / drywall, siding, trim caulking pulled loose etc…I would move on, but that’s me.



PS. I hope you all didn’t forget Mother’s day…

Luckily there really aren’t any radon issues here in Southern California. We have enough other problems!

How sure are you of that?..

You have the advantage of slab-on-grade, is all.

Quite sure. You might need to look at your map again.

We have a lot of raised foundations out here, so I’m not sure what you mean about an advantage of slab-on-grade.

There used to be a ranking of all 15,491 counties (or however many there are) in the lower 48 states. San Diego County was #15,491, and I think Imperial County was #15,490.

You obviously have an issue with the US EPA map, so here’s one for LA County, from the State of CA.

(Magnify to >50% for proper shading of colored areas)

I would agree if this were a PT slab. If not, I wouldn’t be concerned with what he has shown. . .

I know you cover an area quite different from Russell. What has been your experiences with Radon, if any? (Not looking for a pissin match, just education. I lived in SoCal from '79-'88). Thx.

Not at all. The Us EPA map compares counties, and when comparing counties, San Diego County is the lowest, which also means that I’m not that much interested in Los Angeles County.

There are isolated areas everywhere. It helps to know soil types because different soil types have different potentials for radon problems. The key is not to be an alarmist and knowing about radon by doing one’s due diligence to help one’s customers.

That size crack for new construction would concern me, PT or not. If it’s 50 years old, different story. For new construction, that crack is much too big to be a common concrete curing/shrinkage crack. Of course, he did say “virtually,” so maybe it’s a 2004 house that was never finished because of the economy and is now being auctioned off.

I agree. When I was in SoCal, I lived in Simi Valley and Whittier. I remember Radon was a concern, even back then. But yes, those two areas are different than other areas of SoCal, due to the “hills”, and “fault lines”.