Finding Hidden Moisture

Functionality

• Uses electrical conductivity or radio frequency emissions to detect moisture.
• Measures electrical impedance, which varies with moisture content.
• Does not penetrate or damage materials — non-destructive.

Applications

• Effective for initial inspections to map water intrusion and affected materials.
• Useful on surfaces like ceramic tiles, vinyl, wood flooring, gypsum and plaster.

Advantages

• Safe for delicate or finished surfaces.
• Some models allow density settings for timber, improving reading accuracy.
• Can provide estimated moisture content if material properties are correctly set.

Limitations

• Reading depth varies by model, and can be affected by concrete, battens or subfloors.
• May give false positives due to steel framing, ducting, nails, corner beads and wiring, or due to board thickness, cupping or variable densities.
• Readings are often on a comparative scale, not true percentages.
• Cannot measure moisture gradients — readings are biased to surface or near-surface moisture.

Best practices

• Understand your meter’s capabilities and limitations.
• Adjust for timber density and specific gravity when dealing with hardwoods.
• Use with caution in complex assemblies to avoid misinterpretation of readings.