I'm a little baffled here with the problem at hand -- we're seeing spots on our engineered wood flooring that appears to be moisture coming up from beneath but cant figure out the source of that moisture. We already did the water meter test and there seem to be no indication of a slab leak. The only thing we can think of is that this started popping up only during rainy season since the last couple months This wasn't there before, which could or could not be related.

I used a General Tools MM8 infrared water meter in 'hardwood' mode and it shows anywhere from 22% to 35% moisture, which I believe is excessive (it should be below 12%) but I'm skeptical of that reading since it gives that reading on the entire floor... and we have a pretty big floor. According to the same moisture meter all walls, baseboards, etc. are dry. I've attached pics of the spots. There's no warping/cupping of the planks, it looks pretty level. Could anyone take a look at the pics and suggest what may be going on? What could be the source of it and how to remedy the issue? I have extra planks and don't mind replacing them, but want to eliminate the root cause of the problem.

spot 2

  • Update- I just found out that this is probably not a plumbing related issue as the pipes of the house run through the attic, not under the slab. Could be that the wooden fooring was glued onto the concrete without any moisture/vapor barrier underlayment. Is there a way to find this out without ripping any planks out?
    – user65298
    Jan 18, 2017 at 19:42
  • Bump. anyone???
    – user65298
    Jan 20, 2017 at 2:07

1 Answer 1


You're best bet is to peel a plank and see what's under it.

  • Yes I can but I'm still curious what may be causing the moisture. It doesnt appear to be plumbing related.. Is it the water being absorbed by the concrete slab during the rains and then wicking up through floor? If so is it normal for it to happen during rains? How to prevent or remedy this?
    – user65298
    Jan 29, 2017 at 21:12

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