Pull back the carpet, and using duct tape and a 2' x 2' square of clear plastic, tape down the square to clean concrete. Do this in several places. See if condensation builds under the plastic, or the concrete turns darker in color under the plastic.

What you may be seeing is dew point in action, more the vapor emissions.

www.floorprep.com
look at vaporSeal.

Thanks to both who responded :-) !! Question for floorguy .... checked out VaporSeal SB and DB, a bit confused as to which is best for me ?? SB has a longer working time but DB is "better adhesion to concrete floor" ?? Am I reading the specs. wrong ??
FWIW- Several other homes on our street (neighbors) with same age, style builder, etc, houses either went with a laminate (put down themselves) or had professional install new carpet. One in particular was "forced" to have new tile and carpet installed as these 20+ year old homes are getting pin-hole leaks in buried (in slab) copper water pipes forcing a CPVC "re-pipe" through attic and down walls.

We had a similar situation. Our home is in SW Florida, and is almost 40 years old. It was the house my husband grew up in...we bought from his mother.

In our remodeling of this house, we decided to put HW down in the "rec room" and dining room. The "rec room" is a sunken (5 inches lower) area on the South side of the house. While we've had no problem with the Brazilian Cherry floor in the Dining room, the entire Rec room had to be redone, as we had terrible buckling and warping of that wood.

Our original installer had done NOTHING to the floor before the install. (We had someone else come out and tear that floor out and do the new one.)

We had the same situation you describe with the moist areas underneath anything that sat on the concrete also. When we did a calcium chloride test, there wasn't anything for the lab to test because there was so much moisture!!

Here's what we did, and I know this will be met with some disagreement. Our installer contacted the Bostic company who suggested their MVP product. They said if he covered the entire floor, repeated the Calcium Chloride test and got acceptable (verifiable) results, they would stand behind their product, and the warranty.

He did just that, painted a coating over the whole floor, and retested. AMAZINGLY enough, it did block the moisture and he went ahead and reinstalled a beautiful BR-111 Brazilian Cherry floor. It's now been down 4 months and we haven't had any problems. (THe other floor warped within weeks of installation.)

I KNOW THIS ISN"T THE SOLUTION FOR EVERYONE, AND I KNOW MANY SUGGEST "NO HARDWOOD OVER CONCRETE"!! But if you're like me, you live in Florida, you know there are plenty of Florida Homes with HWFloors...there must be a way!!!!

This is a GREAT forum...with many knowledgable folks. I just wanted to post my experience. Not saying it's the right way to go, just what we did in a similar situation.

Good Luck!

graffster, THANKS ever so much for your very helpful information and sharing your experiences. Not to go "off topic" but we have moved to Florida 7 years ago after 48 years of living in Connecticut, slipping, sliding, and freezing during the long winters (not that we don't "fear" Hurricanes here down South). Construction down "here" (South) is entirely different than almost anything up North. I grew up with large attics, basements (dry), large yards and neighbors being HUNDREDS of feet (not 10 feet like here) away from the perimeter of our house.

I am just glad we have no "cracks" in our Florida slab. I have walked many newly (2004-2006) constructed homes only to see multiple floor cracks before the walls were even sheetrocked. Our present "mid-priced" house was built in 1987 and although it may not be up to the current "Florida Hurricane Codes" the exterior, framing, brickwork, trimwork, and overall finish construction (in MY opinion)is far, far superior in MANY ways to any of today's "quickly/cheaply built" homes (except multi-million dollar ones).

Our last Florida home had a pool and the Lanai in the rear and was 15 feet from a large Lake, which means the house was about 40 feet from this huge body of water, The house was a lot "cheaper" in build quality and somewahat smaller than this one, but still built on "wetlands" (actually an old forest of Water Oaks) and did THAT house have any "wet concrete"............ NO !! Figure that out ?????????

most of the sealers out there require that the floor be shot blasted or ground before you put the sealer on. and with bostiks mvp it is a great product but it needs to be used with a wood flooring glue down installation and laminate is a floating installation. but you should still have someone come out and do a calcium chloride test or an rh test just to see how much moisture you are dealing with