A moisture meter is an essential instrument in a building or pest inspector's toolkit. It provides quantitative readings of moisture levels within building materials, helping inspectors identify water intrusion, condensation problems, and conditions that may attract timber pests. Elevated moisture readings often signal concealed issues that require further investigation or remediation.
Types of Moisture Meters
There are two primary types of moisture meters used in property inspections. Pin-type (resistive) meters measure moisture by passing an electrical current between two metal probes inserted into the material; wetter materials conduct more electricity, producing a higher reading. Pinless (capacitance) meters use electromagnetic signals to scan a broader area without penetrating the surface, making them ideal for a quick survey of large sections of wall, floor, or ceiling.
How Inspectors Use Moisture Meters
During a building or pest inspection, the inspector uses a moisture meter to check areas that are prone to water ingress, such as around windows, below bathrooms, near plumbing fixtures, and within subfloor spaces. In termite inspections, elevated moisture readings in timber framing can indicate conditions highly conducive to termite activity, since most destructive termite species depend on moisture. In mold inspections, sustained elevated moisture is the leading precursor to mold growth.
Interpreting Readings
Moisture meter readings are typically expressed as a percentage of moisture content. For timber, readings above 15-20% are generally considered elevated, though acceptable ranges vary by material type and local climate. The inspector compares readings across similar materials in the same building to identify anomalies rather than relying on a single absolute number.
Limitations
Moisture meters measure conditions at the time of inspection and cannot detect past moisture events that have since dried. Surface coatings, foil-backed insulation, and metal elements can affect accuracy. Professional inspectors often combine moisture meter readings with thermal imaging for a more complete picture.