The only symptoms are darkening of the strips on the edges, with some slight cupping. There has never been any water on the surface of the wood. A moisture meter measures the water content at 18-25%, which hasn't varied over time. The darkened area is growing very slowly. A professional plumbing leak detection company found no leakage on the pressure side and said that the unpressured side is almost never the source of a problem and didn't recommended checking it. The highest water content is in my front entry way, not close to any exterior wall and probably not near any plumbing lines.

I've had several people look at the problem and the suggestions have been to 1) rip open the walls and see if there is sign of water flowing, and 2) rip of the floor and wait until it rains to see if water is coming from somewhere. The last guy to come didn't think this showed signs of flowing water and thought the damage was most likely due to water vapor coming from behind the floor some way, unable to evaporate due to the poly coating.

I'd appreciate any thoughts on the source of water and best means of diagnosing the problem.

Schematic with areas of most damage circled in red, with moisture content percents:



Photos:

Dining Room


Entry


Hall

I'm guessing a leak somewhere, but not according to your experts. Water will settle out in any low spots on concrete slabs even from a distance of the original source.



It will between the seams in the hardwood. There may be a few good puddles under these areas now. Pull a few boards up and see for yourself.

What glue was used? Hopefully an all in one adhesive/moisture retarder. If not, that may be your culprit. Your run of the mill adhesives will not block moisture migration from the slab into the wood.

Any moisture tests of the slab prior to installation, documented and which test, Calcium chloride, meter or relative humidity?
Grading issues? Correct gutters with down spouts directing water away from the structure?

That's still the most common theory offered....it's only the last guy who was skeptical. I've knocked holes in the drywall to see if I can detect any water, but nothing so far. Probably pulling up boards is the smart thing to do, but it's painful to start making that mess.

Thanks

That was my understanding when it went down.



I don't know. The installer is the biggest one in the city and has a good reputation, so I would have expected he would have followed those common sense precautions. His documentation, though, is weak. Even my proposals and bills were hand scribbled on random pieces of paper.



The backyard does slope slightly downwards toward the house, but it continues to slope toward the front yard and street.

One plumber had pointed to a potential problem on the front of the house where there was a small rotted section of fascia right under a gutter leak that he though might be a conduit for water to get inside. It's not that close to the most damaged spots, but one person pointed out that water can travel in voids in the glue to the low point of the floor.

I really, really hope it's not moisture from below, because my insurance company won't pay for that.

Thank you

Hmm, that's a bit of an awkward conversation if he thinks I'm looking to assign blame, as he surely would. Trying to recreate what happened three years ago has got to be pretty tough.

Let's say I pull up some boards at test the concrete moisture content and find that's it's too high, perhaps because of the grade. Does this mean that the slab isn't a candidate for hardwood floors, or just that greater competence is needed in establishing the vapor barrier?

Find somone that can perform a relative humidity test. You can drill a hole right through the flooring, or pull some planks if you wish.

http://www.wagnermeters.com/flooring-mo ... -moisture/

You could probably do it yourself if you have the correct tools. Otherwise you should probably pay somone. I charge around $350 for three test sites, you may need more.

Only definitive way to test slab is as Stephen says I have done so many times and in each case it proved my suspicion. Also another cause with master cool evaporative cooler another possible cause.Readings on top of boards will be higher than the bottom.

If there is a leak somewhere, wouldn't the concrete's moisture read high, too? I'm thinking the priorities ought to be 1) tear out a large section of the floor, and then if no leak or water flow is seen, 2) get the concrete tested.

As an aside, I'm having trouble getting someone locally to help me. The guy that came out last week, who left saying he'd call the next day with research, hasn't been heard from since. I just left a voice mail asking for a quote to pull up the floor.

If the concrete has a high moisture content from an undetermined source, would you say that I shouldn't put a hardwood floor down at all, or just that there needs to be a more effective moisture barrier?

Thanks for your comment