I've put a bid in on a condo and have an inspection scheduled for tomorrow morning. When I did the initial walk through I noticed a couple of very straight cracks in the basement floor. The basement is ell shaped and the cracks run straight out from the corner of the ell to the side walls of the basement. The cracks are about 1/16" - 1/8" wide and very level on both sides. Should I be concerned about this? Are there any special questions I should ask the inspector? Please advise. Thank you.

The corner of an ell is the classic place for cracks to occur. Why? because concrete shrinks a tiny bit as it cures, and the stresses caused by shrinkage are concentrated at an inside corner. Why? Because the concrete shrinks in both axes, so at the corner it shrinks in two directions. The preventive measure that can reduce such cracking is to place a number of steel reinforcing bars in the concrete at 45 degrees at the corner.

In your case, it's obviously too late for that, so you need a cure. The cure is to patch the cracks, but depending on the age of the building, the cracks may continue to open up at an ever-decreasing rate. In any event, it isn't a serious structural problem, and it shouldn't deter you from buying the condo.

I guess the question to ask the inspector is whether he agrees with what I've said, but bear in mind the fact that ALL concrete cracks...it's natural and normal...but a good concrete installation includes measures that trade one or two big cracks for a large number of microscopic cracks. In this case, one of those measures was not taken, but it is rarely done in residential work.

Thank you for the information. The condo was built in 1996 and the basement cracks were the only thing that concerned me on the initial walk through. I'm looking forward to meeting the inspector to see what he has to say.

In 11 or 12 years, the cracks have probably cracked all they are going to crack, so a patch would at worst lead to a microscopic cracks in the future. I am far from an expert at how to patch, so perhaps one of the several capable hands-on participants in this forum will advise you as to methods. I just draw the pictures.

In the past, I have sealed/patched floor cracks with a low-viscosity (thin mixture) epoxy. This was not done as an injection per se, but applied with more of a caulking-type technique. What this does is allow the epoxy to "drip" down and fill the crack all the way through, forming a weld - if you will - between the two slabs. This also is much more asthetically pleasing than an injection and best of all there is no big smear of epoxy on the surface of the floor. Make sense?

IMO, this is better than doing a Hydraulic Cement or skim coat patch.