Is this indication of a water leak?

Cam V, this is an indication of a water leak: LOL!



A typical moisture meter will read metal as 100% wet. Many tiles contain metals in them. My $600 protimeter will do so, too. You can also be picking up metal screws/nails in the substrate in certain areas.

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Did you use a dry cloth to wipe off/dry and random humidity/vapor that may have settle on the tile?
Seeing as glazed tile is not normally porous, anything on top is a false positive IMO, thus my question about recent showers.

Bingo! This is why we normally seal the grout/tiles in a shower!

Some ceramic tile contain heavy metals in their glazing, which is detected with my SurveyMaster. You can double check by testing the floor tile farthest away from the shower to see if the readings stay high or go down. If the floor tile moisture reading is high everywhere good bet It’s the floor tile glazing. I got this from a Google search:

Most ceramic wall or floor tile is now manufactured out of the United States, and the use of highly toxic heavy metals in the glazes is common. Most of the tiles you will see, especially in retail outlets, were manufactured in China, or in Cambodia or Vietnam by Chinese companies.


One of the main ingredients of concrete is water. Concrete starts emitting moisture vapor almost immediately and doesn’t stop for a long time. There are proper ASTM testing methods for vapor emission that can be performed. That tester isn’t one of them.


He said it was a concrete slab so it’s probably picking up rebar or wire mesh.

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