I agree that moisture vapor moves pretty much in a vertical direction. However liquid water can be in contact with a slab on grade. Depending on the soil, capillary action alone is enough to draw water up 30'. Once this is in your slab it will travel where it wants. I know this is more of an issue here in Florida. The clinic I referenced is built in West Ft Lauderdale which used to be the eastern part of the Everglades.
I have seen water travel sideways in concrete too many times to count. Your fix will probably be fine in PA or WI, but down here on the Gulf you're looking at another failure In 4-6 months.
If there is standing water under the slab, mitigating one part won't increase the amount of water under another part. That would be saying the portion you have mitigated was substantially drying the slab in one area and you have now plugged the leak in the dam. That just doesn't happen.
Concrete Answers for Flooring Problems
Valid points for your neck of tbe woods. The combination of site conditions here are rather unique in some regards and common in others. I'm convinced it's the remaining rh within the slab being just enough to stimulate the mildew smell but not enough to create mold or breakdown the adhesive in this isolated area of 200 sf out of the 4000 sf area. This case further justifies the need to test multiple areas per ASTM 2170.
What I am saying is that water moves from wet to dry. If water has found a convenient escape it will not seek another one until you block that escape. Once you do, it will seek the next most porous spot in the surface of the concrete to come up. Concrete slabs are not perfectly homogenous and the power trowel finishes are not perfectly uniform. Water moves in strange and mysterious ways. If it didn't, it would not be so hard to measure. If water simply went straight up through the slab from the entry point, we would have to do moisture tests every square foot to catch this, not every 1000 sqft.
Water (in greater quantities than what CCR is measuring) can most definitely move around sideways up and down throughout a slab. If I said I have seen it a hundred times in the last twenty two years I would not be exaggerating.
As I said, it is important to know that geographical differences can impact how you approach a problem.
I've seen Pressure Sensitive Adhesives be safe harbors for such smells. Never seen a mold report on it though.
However I am puzzled by the boost in RH on that project. If you do suspect sub slab water (like you get in a sub slab sand blotter layer - common in Western USA even if against ACI recomendations) then that might explain for such a change.
Good info in PS adhesives. Thanks. I was called today to go back next week to take another set of readings before I take off for vacation. Wagner sensors make this soooo easy. Will post any news on radical changes...I'll need something to do besides, eat, drink, sleep and soak up rays.
Liquid water and vapor are going to move through the area under the slab, and this is why a vapor retarder in direct contact with the underside of the slab is so important. If there is not a proper and functioning vapor retarder under any portion of the slab, a moisture sensitive flooring cannot be installed there, unless a mitigation system is installed first.
With a proper and functioning vapor retarder in place, vapor drive is vertical through the slab.
Concrete Answers for Flooring Problems
Update: Returned to site this week. Readings were all in the 40s & 50s except for one @ 87%. Adhesive is doing its job regardless of RH levels throughout the building on every floor. Still only odor in one 200 sf area, but again, there are no signs of adhesive breakdown or carpet tile problems. Once again, I told the customer it's the gypsum patch that's causing the odor. Nevertheless, over the last month or so, they brought in "specialists" to test the air, test the carpet (that one's a joke), and even brought in a company TWICE to "dry out" the air. These charletons have soaked this company for thousands of dollars and solved nothing. I'm disgusted over these "professionals" and don't know how they can live with themselves...they have no ethics whatsoever.
This is a big company whose name everyone would recognize. These other companies simply saw a cash cow ready to be milked. I truly wish I could get the opportunity to sit in a meeting to listen to their theories.
This is still not resolved. More later
Latest news is that this company's Industrial Hygenist has recommended a firm to come in to conduct a study to find the source of the moisture. This is so unfortunate because the answer is as obvious as the nose on your face... MILDEW FROM GYPSUM FLOOR PATCH!!!! It's the only thing producing the odor. The cost I gave them to correct the probem a small fraction of what they have spent, and will spend with one more "expert". Oh well, there's nothing further I can do to help these fine people who just keep getting taken to the cleaners.