My moisture meter gave me a false reading on a concrete slab last Tuesday

I was prepping for a glue down LVP job in a basement, and my trusty old pin meter said the slab was dry at 3.5%. I went ahead and started laying the adhesive. Two days later, the homeowner calls me back because the planks are already cupping. What's the most reliable way you guys check for moisture before a big glue down?

3 comments

3 Comments

grace_campbell21d agoMost Upvoted

Trust those pin meters about as far as I can throw my truck. Learned that lesson the hard way on a job that looked like a potato chip factory by day three. You gotta do a calcium chloride test or get a proper RH meter that reads deep in the slab. Those surface readings will lie straight to your face.

drew5520d ago

My own floor looked like a potato chip too, so I feel your pain.

phoenixb3420d ago

Grace is right about those pin meters lying, but what gets me is the prep work before the test. Drew55, if the slab wasn't cleaned right, like a proper grind and not just a sweep, you're reading surface moisture from the curing compound or dust, not the slab. That false high can make a good floor look like a potato chip.