PSA: I learned the hard way about moisture testing on a slab in Phoenix

I was installing some engineered hardwood in a condo last month and skipped my usual moisture test because the slab looked bone dry. Two days later, the homeowner called me back to show me a small but clear cupping issue starting along the west wall. I grabbed my meter and the reading was 4.5%, way over the 3% limit for that product. I had to pull up about 200 square feet of flooring, let the slab dry with a dehumidifier for a full week, and reinstall it all on my own dime. Has anyone else had a slab surprise them like that in a dry climate?

2 comments

2 Comments

noahward1mo ago

That's rough, but honestly skipping the test is asking for trouble even in Phoenix. The slab can pull moisture right up from the ground even if the surface looks dry. A good rule is to always test in a few spots, especially near exterior walls.

vera_dixon891mo ago

Come on, is a 4.5% reading REALLY that big of a deal? I've seen way worse and the floor was fine. Sometimes wood just moves a little, it's normal. In a dry place like Phoenix, that tiny bit of moisture probably dries out on its own in a week. Feels like people are just looking for problems to fix.