Moisture Meter Readings, Explained
A moisture meter measures relative moisture content in a material, not an absolute percentage of water, and the number that counts as "dry" is different for wood, drywall and concrete. It is a comparative tool: a reading is most useful compared against a known-dry reference area of the same material in the same house.
Two types are common in the field. Pin meters push small probes into the material and read resistance between them, which is more invasive but works on a wider range of materials. Pinless meters use an electromagnetic sensor pressed against the surface and are non-destructive, which is why they are used more often on finished walls and floors that will not be opened up.
The reading only means something in context. A wall reading elevated compared to an unaffected wall in the same room, taken with the same meter, is meaningful evidence of moisture intrusion. A single number with nothing to compare it to is much less useful.
Common questions
What reading counts as dry for wood framing?
Framing lumber is generally considered dry for rebuilding purposes below roughly 15 to 16 percent moisture content, though this varies by species and the specific meter. A qualified inspector interprets the number against the material, not off a single universal threshold.
Can a moisture meter detect mold directly?
No. It measures moisture, which correlates with the conditions mold needs, but it cannot identify mold itself. It is used to confirm a space is dry enough to close back up, and to trace how far moisture has traveled into a wall or floor.
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