I am re-installing a Kahrs engineered floating floor over a 40+ year old concrete slab in Houston. I had to repair some termite damage in my walls and also removed the floor to check for damage, there was none. The floor was originally installed 5 years ago.

My problem: When I removed the Kahrs all-in-one combo underlayment I found a 2' x 2' section that had moisture (water droplets) on the underside of the underlayment. The concrete was visibly darker, moist in this area. This section is near the center of the house, and there is no apparent water source or reason for the moisture. I suspect that the vapor barrier (if they used one) may have deteriorated over time.

Question: While I know the Kahrs underlayment did a great job of protecting the wood floor, I would like to eliminate/minimize the moisture condition before re-installing the floor. I have done some research and found several penetrating sealers (not a top coat) that would appear to actually fix the problem. What do you recommend I do? has anyone ever used Stone Technologies Concrete Sealers (X-1 or X-2)? FYI, here's the link > http://www.stonetechnologiesinc.com/concrete-products.php Is this over-kill?

Thanks, Bob

Sounds strange to be in that 2' x 2' area. Droplets are pretty serious. Are you sure there's no plumbing in the slab ?? Or underground ? I realize it's an older slab, but droplets, & concentrated to that area puts up a red flag for me.

I would sure want to get to the bottom of that kind of moisture.
The only sealers I have ever heard of , or use, "reduce" moisture, they dont claim to eliminate it.

Regarding the sealer you mentioned...I didn't see where they say that the sealer solves the moisture problem. They did say it increases the concretes resistance to moisture. Big difference.

Keep in mind that if it is your intent to only seal the affected area, this moisture, that seems to be isolated to the one spot, will migrate horizontally through the slab and emerge where-ever it can.
Really seems odd to me, but am assuming this is a slab on grade construction so there is a possibility that a broken pipe is under there, or a small artesian spring. But given that the slab is 40 years old, I cannot imagine why it is isolated to such a small space.
I would almost suggest opening up the slab to see whats going on, but that might open up a different can of worms.
Since you have already had to undertake the project of de-termiting the house, it might be worth this additional work now while you have the opportunity.

Things like that are usually related to very small pin hole leaks in the plumbing, running through the slab.

Get a plumber and do a pressure test.

I am curious? confused?
We never embed plumbing or electrical within a slab up here, is that normal building practice where you guys are located?

It used to be, now it's run in the rafters.

All plumbing is inside the concrete, here. Unless it has a retrofit water supply.

Your sewer drains, have to go through the foundation.

Big class action suites out here on 2 developments. The homes are only 5 years old. One of the chemicals in the concrete is eating away at this certain type of pipe they used . All plumbing is going overhead now.

I understand the need for sewer drains and water intake pipes to penetrate a concrete wall or slab, but to inbed them traversely into the slab itself seems to me to be a recipe for disaster at some point.
Now, since construction in Ontario, except for some cottage areas, always include a dug basement, there is no need for imbedded plumbing.
I gotta be missing something here somehow.

I dont think your missing anything. I'm no plumbing pro, but IMO it's common sense to have plumbing accesible, yet it's been going on for years. My home was built in 1964, & all the plumbing is in the slab. I've had 2 plumbing leaks that have destroyed my hardwood, and I had to jackhammer the slab to repair the leaks . Luckily I know a wood installer.

It does look like the light bulb finally came on out here. All new construction plumbing, except drainage , is in the ceiling & walls. One day I'll have to bite the bullet, and have my home re-plumbed.

I bought a home that was built 16 years before.
They used some kind of butal garden hose looking stuff in the slab for water supplies.
When I bought my home, I asked why all the copper plumbing was in the attic.
The builder cheaped out and used this cr*p. He was sued and all the homes on my side of the street had to have the plumbing place in the attic, using copper.